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Hedonism

Hedonism refers to the prioritization of pleasure in one's lifestyle, actions, or thoughts. The term can include a number of theories or practices across philosophy, art, and psychology, encompassing both sensory pleasure and more intellectual or personal pursuits, but can also be used in everyday parlance as a pejorative for the egoistic pursuit of short-term gratification at the expense of others.

The term originates in ethical philosophy, where axiological or value hedonism is the claim that pleasure is the sole form of intrinsic value, while normative or ethical hedonism claims that pursuing pleasure and avoiding pain for oneself or others are the ultimate expressions of ethical good. Applied to well-being or what is good for someone, it is the thesis that pleasure and suffering are the only components of well-being.

Psychological or motivational hedonism claims that human behavior is psychologically determined by desires to increase pleasure and to decrease pain.

The nature of pleasure

Pleasure plays a central role in all forms of hedonism; it refers to experience that feels good and involves the enjoyment of something. Pleasure contrasts with pain or suffering, which are forms of feeling bad. Discussions within hedonism usually focus more on pleasure, but as its negative side, pain is equally implied in these discussions. Both pleasure and pain come in degrees and have been thought of as a dimension going from positive degrees through a neutral point to negative degrees. The term "happiness" is often used in this tradition to refer to the balance of pleasure over pain.

In everyday language, the term "pleasure" is primarily associated with sensory pleasures like the enjoyment of food or sex. But in its most general sense, it includes all types of positive or pleasant experiences including the enjoyment of sports, seeing a beautiful sunset or engaging in an intellectually satisfying activity. Theories of pleasure try to determine what all these pleasurable experiences have in common, and what is essential to them. They are traditionally divided into quality theories and attitude theories. Quality theories hold that pleasure is a quality of pleasurable experiences themselves while attitude theories state that pleasure is in some sense external to the experience since it depends on the subject's attitude to the experience.

The plausibility of the various versions of hedonism is affected by how the nature of pleasure is conceived. An important appeal of most forms of hedonism is that they are able to give a simple and unified account of their respective fields. But this is only possible if pleasure itself is a unified phenomenon. This has been put into question, mainly due to the wide variety of pleasure experiences which seem to have no one shared feature in common. One way open to quality theorists to respond to this objection is by pointing out that the hedonic tone of pleasure-experiences is not a regular quality but a higher-order quality. Attitude theories have an easier way to reply to this argument since they may hold that it is the same type of attitude, often identified with desire, that is common to all pleasurable experiences.

Psychological hedonism
Psychological hedonism, also known as motivational hedonism, is an empirical theory about what motivates us: it states that all actions by humans aim at increasing pleasure and avoiding pain. This is usually understood in combination with egoism, i.e. that each person only aims at their happiness. For example, Thomas Hobbes theorized that a person's ego was the primary impulse in determining their behavior. Human actions rely on beliefs about what causes pleasure. False beliefs may mislead and thus each person's actions may fail to result in pleasure, but even failed actions are motivated by considerations of pleasure, according to psychological hedonism. The paradox of hedonism concerns the thesis that pleasure-seeking behavior is self-defeating in the sense that it results in less actual pleasure than would result from following other motives.

Psychological hedonism gives a straightforward theory explaining the totality of human behavior. It has intuitive plausibility because pleasure-seeking behavior is a common phenomenon, and may indeed dominate human conduct at times; however, the generalization of psychological hedonism as an explanation for all behavior is highly controversial. Critics point to counterexamples involving actions that seem to have no plausible explanation in terms of pleasure, such as egoistic motives for things other than pleasure (e.g. health, self-improvement, post-mortem fame), and altruistic motives (e.g. pursuing one's child's happiness, sacrificing one's life for a greater cause). Psychological hedonists reinterpret such cases in terms of pleasure-seeking behavior, for example positing that seeing one's children happy or knowing that one's death will have been meaningful brings pleasure to the person sacrificing their immediate pleasure.

Critics also contend that, via introspection, one can conclude that the pursuit of pleasure is only one type of motivating force among others and that reinterpreting every case in terms of pleasure/pain contradicts this. Critics also contend that psychological hedonism's basic claim of what motivates humans falls within the realm of the science of psychology rather than philosophy, and as such demands experimental evidence to confirm or contradict it.

Ethical hedonism
Ethical hedonism or normative hedonism, as defined here, is the thesis that considerations of increasing pleasure and decreasing pain determine what people should do or which action is right. However, it is sometimes defined in a wider sense in terms of intrinsic value, in which case it includes axiological hedonism as defined below. It is different from psychological hedonism since it prescribes rather than describes human behavior. In the narrow sense, ethical hedonism is a form of consequentialism since it determines the rightness of an action based on its consequences, which are measured here in terms of pleasure and pain. As such, it is subject to the main arguments in favor and against consequentialism. On the positive side, these include the intuition that the consequences of human actions matter and that, through them, humans ought to make the world a better place. On the negative side, consequentialism would entail that humans rarely if ever know right from wrong since human knowledge of the future is rather limited and the consequences of even simple actions may be vast. As a form of hedonism, it has some initial intuitive appeal since pleasure and pain seem to be relevant to how people should act. But it has been argued that it is morally objectionable to see pleasure and pain as the only factors relevant to what humans should do since this position seems to ignore, for example, values of justice, friendship and truth. Ethical hedonism is usually concerned with both pleasure and pain. But the more restricted version in the form of negative consequentialism or negative utilitarianism focuses only on reducing suffering. Ethical hedonism is said to have been started by Aristippus of Cyrene, who held the idea that pleasure is the highest good and later was revived by Jeremy Bentham.

Ethical hedonist theories can vary in relation to whose pleasure is held within the circle of concern. Individualist forms of hedonism can overlap with Ethical egoism, dictating that each agent has no moral obligation beyond their own pleasure. This position is usually not held in very high esteem. Altruist theories, commonly known by the term "classical utilitarianism", are more respectable in the philosophical community. They hold that the agent should maximize the sum-total of everyone's happiness. This sum-total includes the agent's pleasure as well, but only as one factor among many. A common objection against utilitarianism is that it is too demanding. This is most pronounced in cases where the agent has to sacrifice his own happiness in order to promote someone else's happiness. For example, various commentators have directed this argument against Peter Singer's position, who suggests along similar lines that the right thing to do for most people living in developed countries would be to donate a significant portion of their income to charities, which appears overly demanding to many. Singer justifies his position by pointing out that the suffering that can be avoided in third world countries this way considerably outweighs the pleasure gained from how the money would be spent otherwise. Another common objection to utilitarianism is that it disregards the personal nature of moral duties, for example, that it may be more important to promote the happiness of others close to each individual person, such as family and friends, even if the alternative course of actions would result in slightly more happiness for a stranger.

Axiological hedonism
Axiological hedonism is the thesis that only pleasure has intrinsic value. It has also been referred to as evaluative hedonism or value hedonism, and it is sometimes included in ethical hedonism. A closely related theory often treated together with axiological hedonism is hedonism about well-being, which holds that pleasure and pain are the only constituents of well-being and thereby the only things that are good for someone. Central to the understanding of axiological hedonism is the distinction between intrinsic and instrumental value. An entity has intrinsic value if it is good in itself or good for its own sake. Instrumental value, on the other hand, is ascribed to things that are valuable only as a means to something else. For example, tools like cars or microwaves are said to be instrumentally valuable in virtue of the function they perform, while the happiness they cause is intrinsically valuable. Axiological hedonism is a claim about intrinsic value, not about value at large.

Within the scope of axiological hedonism, there are two competing theories about the exact relation between pleasure and value: quantitative hedonism and qualitative hedonism. Quantitative hedonists, following Jeremy Bentham, hold that the specific content or quality of a pleasure-experience is not relevant to its value, which only depends on its quantitative features: intensity and duration. For example, on this account, an experience of intense pleasure of indulging in food and sex is worth more than an experience of subtle pleasure of looking at fine art or of engaging in a stimulating intellectual conversation. Qualitative hedonists, following John Stuart Mill, object to this version on the grounds that it threatens to turn axiological hedonism into a "philosophy of swine". Instead, they argue that the quality is another factor relevant to the value of a pleasure-experience, for example, that the lower pleasures of the body are less valuable than the higher pleasures of the mind.

One appeal of axiological hedonism is that it provides a simple and unified account of what matters. It also reflects the introspective insight that pleasure feels valuable as something worth seeking. It has been influential throughout the history of western philosophy but has received a lot of criticism in contemporary philosophy. Most objections can roughly be divided into 2 types: (1) objections to the claim that pleasure is a sufficient condition of intrinsic value or that all pleasure is intrinsically valuable; (2) objections to the claim that pleasure is a necessary condition of intrinsic value or that there are no intrinsically valuable things other than pleasure. Opponents in the first category usually try to point to cases of pleasure that seem to either lack value or have negative value, like sadistic pleasure or pleasure due to a false belief. Qualitative hedonists can try to account for these cases by devaluing pleasures associated with the problematic qualities. Other ways to respond to this argument include rejecting the claim that these pleasures really have no or negative intrinsic value or rejecting that these cases involve pleasure at all.

Various thought experiments have been proposed for the second category, i.e. that there are intrinsically valuable things other than pleasure. The most well-known one in recent philosophy is Robert Nozick's experience machine. Nozick asks whether people would agree to be permanently transported into a simulated reality more pleasurable than actual life. He thinks that it is rational to decline this offer since other things besides pleasure matter. This has to do with the fact that it matters to be in touch with reality and to actually "make a difference in the world" instead of just appearing to do so since life would be meaningless otherwise. Axiological hedonists have responded to this thought experiment by pointing out that human intuitions about what people should do are mistaken, for example, that there is a cognitive bias to prefer the status quo and that if people were to find out that people had spent human life already within the experience machine, people would be likely to choose to stay within the machine. Another objection within this category is that many things besides pleasure seem valuable to us, like virtue, beauty, knowledge or justice. For example, G. E. Moore suggests in a famous thought experiment that a world consisting only of a beautiful landscape is better than an ugly and disgusting world even if there is no conscious being to observe and enjoy or suffer either world. One way for the axiological hedonist to respond is to explain the value of these things in terms of instrumental values. So, for example, virtue is good because it tends to increase the overall pleasure of the virtuous person or of the people around them. This can be paired with holding that there is a psychological bias to mistake stable instrumental values for intrinsic values, thus explaining the opponent's intuition. While this strategy may work for some cases, it is controversial whether it can be applied to all counterexamples.

Aesthetic hedonism
Aesthetic hedonism is the influential view in the field of aesthetics that beauty or aesthetic value can be defined in terms of pleasure, e.g. that for an object to be beautiful is for it to cause pleasure or that the experience of beauty is always accompanied by pleasure. A prominent articulation of this position comes from Thomas Aquinas, who treats beauty as "that which pleases in the very apprehension of it". Immanuel Kant explains this pleasure through a harmonious interplay between the faculties of understanding and imagination. A further question for aesthetic hedonists is how to explain the relation between beauty and pleasure. This problem is akin to the Euthyphro dilemma, i.e. the issue whether something is beautiful because it is enjoyed or whether it is enjoyed because it is beautiful. Identity theorists solve this problem by denying that there is a difference between beauty and pleasure: they identify beauty, or the appearance of it, with the experience of aesthetic pleasure.

Aesthetic hedonists usually restrict and specify the notion of pleasure in various ways in order to avoid obvious counterexamples. One important distinction in this context is the difference between pure and mixed pleasure. Pure pleasure excludes any form of pain or unpleasant feeling while the experience of mixed pleasure can include unpleasant elements. But beauty can involve mixed pleasure, for example, in the case of a beautifully tragic story, which is why mixed pleasure is usually allowed in aesthetic hedonist conceptions of beauty.

Another problem faced by aesthetic hedonist theories is that people are known to have taken pleasure from many things that are not beautiful. One way to address this issue is to associate beauty with a special type of pleasure: aesthetic or disinterested pleasure. A pleasure is disinterested if it is indifferent to the existence of the beautiful object or if it did not arise due to an antecedent desire through means-end reasoning. For example, the joy of looking at a beautiful landscape would still be valuable if it turned out that this experience was an illusion, which would not be true if this joy was due to seeing the landscape as a valuable real estate opportunity. Opponents of hedonism usually concede that many experiences of beauty are pleasurable but deny that this is true for all cases. For example, a cold jaded critic may still be a good judge of beauty due to his years of experience but lack the joy that initially accompanied his work. One way to avoid this objection is to allow responses to beautiful things to lack pleasure while insisting that all beautiful things merit pleasure, that aesthetic pleasure is the only appropriate response to them.

Etymology
The term hedonism derives from the Greek hēdonismos (ἡδονισμός; from ἡδονή), which is a cognate from Proto-Indo-European swéh₂dus through Ancient Greek hēdús (ἡδύς)  or   hêdos (ἧδος) + suffix -ismos (-ισμός, 'ism').

Opposite to hedonism, there is hedonophobia, which is a strong aversion to experiencing pleasure. According to medical author William C. Shiel Jr., hedonophobia is "an abnormal, excessive, and persistent fear of pleasure." The condition of being unable to experience pleasure is anhedonia.

Sumerian civilization
In the original Old Babylonian version of the Epic of Gilgamesh, Siduri gave the following advice: "Fill your belly. Day and night make merry. Let days be full of joy. Dance and make music day and night.... These things alone are the concern of men." This may represent the first recorded advocacy of a hedonistic philosophy.

Cyrenaic school

The Cyrenaics were a hedonist Greek school of philosophy founded in the 4th century BC by Socrates' student, Aristippus of Cyrene, although many of the principles of the school are believed to have been formalized by his grandson of the same name, Aristippus the Younger. The school was so called after Cyrene, the birthplace of Aristippus and where he began teaching. It was one of the earliest Socratic schools. The school died out within a century.

The Cyrenaics taught that the only intrinsic good is pleasure, which meant not just the absence of pain, but positively enjoyable momentary sensations. Of these, physical ones are stronger than those of anticipation or memory. They did, however, recognize the value of social obligation, and that pleasure could be gained from altruism.

The Cyrenaics were known for their skeptical theory of knowledge, reducing logic to a basic doctrine concerning the criterion of truth. They thought that people can know with certainty only immediate sense-experiences (for instance, that one is having a sweet sensation), but can know nothing about the nature of the objects that cause these sensations (for instance, that honey is sweet). They also denied that people can have knowledge of what the experiences of other people are like. All knowledge is immediate sensation. These sensations are motions that are purely subjective, and are painful, indifferent or pleasant, according as they are violent, tranquil or gentle. Further, they are entirely individual and can in no way be described as constituting absolute objective knowledge. Feeling, therefore, is the only possible criterion of knowledge and of conduct.

Cyrenaicism deduces a single, universal aim for all people: pleasure. Furthermore, all feeling is momentary and homogeneous; past and future pleasure have no real existence for us, and that among present pleasures there is no distinction of kind. Socrates had spoken of the higher pleasures of the intellect; the Cyrenaics denied the validity of this distinction and said that bodily pleasures, being more simple and more intense, were preferable. Momentary pleasure, preferably of a physical kind, is the only good for humans. However some actions which give immediate pleasure can create more than their equivalent of pain. The wise person should be in control of pleasures rather than be enslaved to them, otherwise pain will result, and this requires judgement to evaluate the different pleasures of life. Regard should be paid to law and custom, because even though these things have no intrinsic value on their own, violating them will lead to unpleasant penalties being imposed by others. Likewise, friendship and justice are useful because of the pleasure they provide. Thus the Cyrenaics believed in the hedonistic value of social obligation and altruistic behaviour.

Epicureanism
Epicureanism is a system of philosophy based upon the teachings of Epicurus (c. 341), founded around 307 BC. Epicurus was an atomic materialist, following in the steps of Democritus and Leucippus. His materialism led him to a general stance against superstition or the idea of divine intervention. Following Aristippus—about whom very little is known—Epicurus believed that the greatest good was to seek modest, sustainable "pleasure" in the form of a state of tranquility and freedom from fear (ataraxia) and absence of bodily pain (aponia) through knowledge of the workings of the world and the limits of desires. The combination of these two states is supposed to constitute happiness in its highest form. Although Epicureanism is a form of hedonism, insofar as it declares pleasure as the sole intrinsic good, its conception of absence of pain as the greatest pleasure and its advocacy of a simple life make it different from "hedonism" as it is commonly understood.

In the Epicurean view, the highest pleasure (tranquility and freedom from fear) was obtained by knowledge, friendship and living a virtuous and temperate life. He lauded the enjoyment of simple pleasures, by which he meant abstaining from bodily desires, such as sex and appetites, verging on asceticism. He argued that when eating, one should not eat too richly, for it could lead to dissatisfaction later, such as the grim realization that one could not afford such delicacies in the future. Likewise, sex could lead to increased lust and dissatisfaction with the sexual partner. Epicurus did not articulate a broad system of social ethics that has survived but had a unique version of the Golden Rule:

"It is impossible to live a pleasant life without living wisely and well and justly (agreeing 'neither to harm nor be harmed'), and it is impossible to live wisely and well and justly without living a pleasant life."

Epicureanism was originally a challenge to Platonism, though later it became the main opponent of Stoicism. Epicurus and his followers shunned politics. After the death of Epicurus, his school was headed by Hermarchus; later many Epicurean societies flourished in the Late Hellenistic era and during the Roman era (such as those in Antiochia, Alexandria, Rhodes and Ercolano). The poet Lucretius is its most known Roman proponent. By the end of the Roman Empire, having undergone Christian attack and repression, Epicureanism had all but died out.

Some writings by Epicurus have survived. Some scholars consider the epic poem On the Nature of Things by Lucretius to present in one unified work the core arguments and theories of Epicureanism. Many of the papyrus scrolls unearthed at the Villa of the Papyri at Herculaneum are Epicurean texts. At least some are thought to have belonged to the Epicurean Philodemus.

Indian philosophy
The concept of hedonism is also found in nāstika ('atheist', as in heterodox) schools of Hinduism, for instance the Charvaka school. However, Hedonism is criticized by āstika ('theist', as in orthodox) schools of thought on the basis that it is inherently egoistic and therefore detrimental to spiritual liberation.

Christianity
Ethical hedonism as part of Christian theology has also been a concept in some evangelical circles, particularly in those of the Reformed tradition. The term Christian Hedonism was first coined by Reformed-Baptist theologian John Piper in his 1986 book Desiring God: "My shortest summary of it is: God is most glorified in us when we are most satisfied in Him. Or: The chief end of man is to glorify God by enjoying Him forever. Does Christian Hedonism make a god out of pleasure? No. It says that we all make a god out of what we take most pleasure in."Piper states his term may describe the theology of Jonathan Edwards, who in his 1746 Treatise Concerning Religious Affections referred to "a future enjoyment of Him [God] in heaven." Already in the 17th century, the atomist Pierre Gassendi had adapted Epicureanism to the Christian doctrine. The medieval Church used allegations of hedonism against some dissenters such as the twelfth-century Waldensians.

Islam
German sociologist, historian, jurist and political economist Max Weber argued that hedonism plays a role in Islamic ethics and teachings, in which worldly pleasures such as military interests and the "acquisition of booty" are emphasised. According to Weber, Islam is the polar opposite of ascetic puritanism.

Utilitarianism
Utilitarianism addresses problems with moral motivation neglected by Kantianism by giving a central role to happiness. It is an ethical theory holding that the proper course of action is the one that maximizes the overall good of the society. It is thus one form of consequentialism, meaning that the moral worth of an action is determined by its resulting outcome. The most influential contributors to this theory are considered to be the 18th and 19th-century British philosophers Jeremy Bentham and John Stuart Mill. Conjoining hedonism—as a view as to what is good for people—to utilitarianism has the result that all action should be directed toward achieving the greatest total amount of happiness (measured via hedonic calculus). Though consistent in their pursuit of happiness, Bentham and Mill's versions of hedonism differ.

There are two somewhat basic schools of thought on hedonism.

Bentham
One school, grouped around Jeremy Bentham, defends a quantitative approach. Bentham believed that the value of a pleasure could be quantitatively understood. Essentially, he believed the value of pleasure to be its intensity multiplied by its duration—so it was not just the number of pleasures, but their intensity and how long they lasted that must be taken into account.

Mill
Other proponents, like John Stuart Mill, argue a qualitative approach. Mill believed that there can be different levels of pleasure—higher quality pleasure is better than lower quality pleasure. Mill also argues that simpler beings (he often refers to pigs) have an easier access to the simpler pleasures; since they do not see other aspects of life, they can simply indulge in their lower pleasures. The more elaborate beings tend to spend more thought on other matters and hence lessen the time for simple pleasure. It is therefore more difficult for them to indulge in such "simple pleasures" in the same manner.

Libertinage
An extreme form of hedonism that views moral and sexual restraint as either unnecessary or harmful. Famous proponents are Marquis de Sade and John Wilmot, 2nd Earl of Rochester.

Contemporary approaches
Contemporary proponents of hedonism include Swedish philosopher Torbjörn Tännsjö, Fred Feldman, and Spanish ethic philosopher Esperanza Guisán (published a "Hedonist manifesto" in 1990). Dan Haybron has distinguished between psychological, ethical, welfare and axiological hedonism.

Michel Onfray

A dedicated contemporary hedonist philosopher and writer on the history of hedonistic thought is the French Michel Onfray, who has written two books directly on the subject, L'invention du plaisir: fragments cyréaniques and La puissance d'exister : Manifeste hédoniste. He defines hedonism "as an introspective attitude to life based on taking pleasure yourself and pleasuring others, without harming yourself or anyone else." Onfray's philosophical project is to define an ethical hedonism, a joyous utilitarianism, and a generalized aesthetic of sensual materialism that explores how to use the brain's and the body's capacities to their fullest extent—while restoring philosophy to a useful role in art, politics, and everyday life and decisions."

Onfray's works "have explored the philosophical resonances and components of (and challenges to) science, painting, gastronomy, sex and sensuality, bioethics, wine, and writing. His most ambitious project is his projected six-volume Counter-history of Philosophy" (which has been extended, with 12 volumes as of 2020). For Onfray:"In opposition to the ascetic ideal advocated by the dominant school of thought, hedonism suggests identifying the highest good with your own pleasure and that of others; the one must never be indulged at the expense of sacrificing the other. Obtaining this balance – my pleasure at the same time as the pleasure of others – presumes that we approach the subject from different angles – political, ethical, aesthetic, erotic, bioethical, pedagogical, historiographical...."For this, he has "written books on each of these facets of the same world view." His philosophy aims for "micro-revolutions", or "revolutions of the individual and small groups of like-minded people who live by his hedonistic, libertarian values."

Abolitionism (David Pearce)

The Abolitionist Society is a transhumanist group calling for the abolition of suffering in all sentient life through the use of advanced biotechnology. Their core philosophy is negative utilitarianism.

David Pearce is a theorist of this perspective who believes and promotes the idea that there exists a strong ethical imperative for humans to work towards the abolition of suffering in all sentient life. His book-length internet manifesto The Hedonistic Imperative outlines how technologies such as genetic engineering, nanotechnology, pharmacology, and neurosurgery could potentially converge to eliminate all forms of unpleasant experience among human and non-human animals, replacing suffering with gradients of well-being, a project he refers to as "paradise engineering." A transhumanist and a vegan, Pearce believes that humans, or posthuman descendants, have a responsibility not only to avoid cruelty to animals within human society but also to alleviate the suffering of animals in the wild.

In a talk given at the Future of Humanity Institute and at the Charity International, 'Happiness Conference', Pearce said:

"Sadly, what won't abolish suffering, or at least not on its own, is socio-economic reform, or exponential economic growth, or technological progress in the usual sense, or any of the traditional panaceas for solving the world's ills. Improving the external environment is admirable and important; but such improvement can't recalibrate our hedonic treadmill above a genetically constrained ceiling. Twin studies confirm there is a [partially] heritable set-point of well-being – or ill-being – around which we all tend to fluctuate over the course of a lifetime. This set-point varies between individuals. It's possible to lower an individual's hedonic set-point by inflicting prolonged uncontrolled stress; but even this re-set is not as easy as it sounds: suicide-rates typically go down in wartime; and six months after a quadriplegia-inducing accident, studies suggest that we are typically neither more nor less unhappy than we were before the catastrophic event. Unfortunately, attempts to build an ideal society can't overcome this biological ceiling, whether utopias of the left or right, free-market or socialist, religious or secular, futuristic high-tech or simply cultivating one's garden. Even if everything that traditional futurists have asked for is delivered – eternal youth, unlimited material wealth, morphological freedom, superintelligence, immersive VR, molecular nanotechnology, etc – there is no evidence that our subjective quality of life would on average significantly surpass the quality of life of our hunter-gatherer ancestors – or a New Guinea tribesman today – in the absence of reward pathway enrichment. This claim is difficult to prove in the absence of sophisticated neuroscanning; but objective indices of psychological distress e.g. suicide rates, bear it out. Unenhanced humans will still be prey to the spectrum of Darwinian emotions, ranging from terrible suffering to petty disappointments and frustrations – sadness, anxiety, jealousy, existential angst. Their biology is part of 'what it means to be human'. Subjectively unpleasant states of consciousness exist because they were genetically adaptive. Each of our core emotions had a distinct signalling role in our evolutionary past: they tended to promote behaviours that enhanced the inclusive fitness of our genes in the ancestral environment."

Hedodynamics
Russian physicist and philosopher Victor Argonov argues that hedonism is not only a philosophical but also a verifiable scientific hypothesis. In 2014, he suggested "postulates of pleasure principle," the confirmation of which would lead to a new scientific discipline known as hedodynamics.

Hedodynamics would be able to forecast the distant future development of human civilization and even the probable structure and psychology of other rational beings within the universe. In order to build such a theory, science must discover the neural correlate of pleasure—neurophysiological parameter unambiguously corresponding to the feeling of pleasure (hedonic tone).

According to Argonov, posthumans will be able to reprogram their motivations in an arbitrary manner (to get pleasure from any programmed activity). And if pleasure principle postulates are true, then general direction of civilization development is obvious: maximization of integral happiness in posthuman life (product of life span and average happiness). Posthumans will avoid constant pleasure stimulation, because it is incompatible with rational behavior required to prolong life. However, they can become on average much happier than modern humans.

Many other aspects of posthuman society could be predicted by hedodynamics if the neural correlate of pleasure were discovered. For example, the optimal number of individuals, their optimal body size (whether it matters for happiness or not) and the degree of aggression.

Criticism
Critics of hedonism have objected to its exclusive concentration on pleasure as valuable or that the retentive breadth of dopamine is limited.

In particular, G. E. Moore offered a thought experiment in criticism of pleasure as the sole bearer of value: he imagined two worlds—one of exceeding beauty and the other a heap of filth. Neither of these worlds will be experienced by anyone. The question then is if it is better for the beautiful world to exist than the heap of filth. In this, Moore implied that states of affairs have value beyond conscious pleasure, which he said spoke against the validity of hedonism.

Perhaps the most famous objection to hedonism is Robert Nozick's famous experience machine. Nozick asks to hypothetically imagine a machine that will allow humans to experience whatever people want—if a person wants to experience making friends, the machine will give this to its user. Nozick claims that by hedonistic logic, people should remain in this machine for the rest of their lives. However, he gives three reasons why this is not a preferable scenario: firstly, because people want to do certain things, as opposed to merely experience them; secondly, people want to be a certain kind of person, as opposed to an 'indeterminate blob' and thirdly, because such a thing would limit their experiences to only what people can imagine. Peter Singer, a hedonistic utilitarian, and Katarzyna de Lazari-Radek have both argued against such an objection by saying that it only provides an answer to certain forms of hedonism, and ignores others.

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title: Hedonism


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Holocene

The Holocene  is the current geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene is an interglacial period within the ongoing glacial cycles of the Quaternary, and is equivalent to Marine Isotope Stage 1.

The Holocene correlates with the last maximum axial tilt of the Earth towards the Sun, and corresponds with the rapid proliferation, growth, and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global significance for the future evolution of living species, including approximately synchronous lithospheric evidence, or more recently hydrospheric and atmospheric evidence of the human impact. In July 2018, the International Union of Geological Sciences split the Holocene Epoch into three distinct ages based on the climate, Greenlandian (11,700 years ago to 8,200 years ago), Northgrippian (8,200 years ago to 4,200 years ago) and Meghalayan (4,200 years ago to the present), as proposed by International Commission on Stratigraphy. The oldest age, the Greenlandian, was characterized by a warming following the preceding ice age. The Northgrippian Age is known for vast cooling due to a disruption in ocean circulations that was caused by the melting of glaciers. The most recent age of the Holocene is the present Meghalayan, which began with extreme drought that lasted around 200 years.

Etymology
The word Holocene was formed from two Ancient Greek words. Hólos (ὅλος) is the Greek word for "whole". "Cene" comes from the Greek word kainós (καινός), meaning "new". The concept is that this epoch is "entirely new". The suffix '-cene' is used for all the seven epochs of the Cenozoic Era.

Overview
The International Commission on Stratigraphy has defined the Holocene as starting approximately 11,700 years before 2000 CE (11,650 cal years BP, or 9,700 BCE). The Subcommission on Quaternary Stratigraphy (SQS) regards the term 'recent' as an incorrect way of referring to the Holocene, preferring the term 'modern' instead to describe current processes. It also observes that the term 'Flandrian' may be used as a synonym for Holocene, although it is becoming outdated. The International Commission on Stratigraphy, however, considers the Holocene to be an epoch following the Pleistocene and specifically following the last glacial period. Local names for the last glacial period include the Wisconsinan in North America, the Weichselian in Europe, the Devensian in Britain, the Llanquihue in Chile and the Otiran in New Zealand.

The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations:
 * Preboreal (10 ka–9 ka BP),
 * Boreal (9 ka–8 ka BP),
 * Atlantic (8 ka–5 ka BP),
 * Subboreal (5 ka–2.5 ka BP) and
 * Subatlantic (2.5 ka BP–present).
 * Note: "ka BP" means "kilo-annum Before Present", i.e. 1,000 years before 1950 (non-calibrated C14 dates)

Geologists working in different regions are studying sea levels, peat bogs, and ice-core samples, using a variety of methods, with a view toward further verifying and refining the Blytt–Sernander sequence. This is a classification of climatic periods initially defined by plant remains in peat mosses. Though the method was once thought to be of little interest, based on 14C dating of peats that was inconsistent with the claimed chronozones, investigators have found a general correspondence across Eurasia and North America. The scheme was defined for Northern Europe, but the climate changes were claimed to occur more widely. The periods of the scheme include a few of the final pre-Holocene oscillations of the last glacial period and then classify climates of more recent prehistory.

Paleontologists have not defined any faunal stages for the Holocene. If subdivision is necessary, periods of human technological development, such as the Mesolithic, Neolithic, and Bronze Age, are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world.

According to some scholars, a third epoch of the Quaternary, the Anthropocene, has now begun. This term is used to denote the present time-interval in which many geologically significant conditions and processes have been profoundly altered by human activities. The 'Anthropocene' (a term coined by Paul J. Crutzen and Eugene Stoermer in 2000) is not a formally defined geological unit. The Subcommission on Quaternary Stratigraphy of the International Commission on Stratigraphy has a working group to determine whether it should be. In May 2019, members of the working group voted in favour of recognizing the Anthropocene as formal chrono-stratigraphic unit, with stratigraphic signals around the mid-twentieth century CE as its base. The exact criteria have still to be determined, after which the recommendation also has to be approved by the working group's parent bodies (ultimately the International Union of Geological Sciences).

Geology
The Holocene is a geologic epoch that follows directly after the Pleistocene. Continental motions due to plate tectonics are less than a kilometre over a span of only 10,000 years. However, ice melt caused world sea levels to rise about 35 m in the early part of the Holocene and another 30 m in the later part of the Holocene. In addition, many areas above about 40 degrees north latitude had been depressed by the weight of the Pleistocene glaciers and rose as much as 180 m due to post-glacial rebound over the late Pleistocene and Holocene, and are still rising today.

The sea-level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea. For example, marine fossils from the Holocene epoch have been found in locations such as Vermont and Michigan. Other than higher-latitude temporary marine incursions associated with glacial depression, Holocene fossils are found primarily in lakebed, floodplain, and cave deposits. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely tectonic uplift of non-glacial origin.

Post-glacial rebound in the Scandinavia region resulted in a shrinking Baltic Sea. The region continues to rise, still causing weak earthquakes across Northern Europe. An equivalent event in North America was the rebound of Hudson Bay, as it shrank from its larger, immediate post-glacial Tyrrell Sea phase, to its present boundaries.

Climate
The climate throughout the Holocene has shown significant variability despite ice core records from Greenland suggesting a more stable climate following the preceding ice age. Marine chemical fluxes during the Holocene were lower than during the Younger Dryas, but were still considerable enough to imply notable changes in the climate.

The temporal and spatial extent of climate change during the Holocene is an area of considerable uncertainty, with radiative forcing recently proposed to be the origin of cycles identified in the North Atlantic region. Climate cyclicity through the Holocene (Bond events) has been observed in or near marine settings and is strongly controlled by glacial input to the North Atlantic. Periodicities of ≈2500, ≈1500, and ≈1000 years are generally observed in the North Atlantic. At the same time spectral analyses of the continental record, which is remote from oceanic influence, reveal persistent periodicities of 1,000 and 500 years that may correspond to solar activity variations during the Holocene Epoch. A 1,500-year cycle corresponding to the North Atlantic oceanic circulation may have had widespread global distribution in the Late Holocene. From 8,500 BP to 6,700 BP, North Atlantic climate oscillations were highly irregular and erratic because of perturbations from substantial ice discharge into the ocean from the collapsing Laurentide Ice Sheet. The Greenland ice core records indicate that climate changes became more regional and had a larger effect on the mid-to-low latitudes and mid-to-high latitudes after ~5600 B.P.

Human activity through land use changes was an important influence on Holocene climatic changes, and is believed to be why the Holocene is an atypical interglacial that has not experienced significant cooling over its course. From the start of the Industrial Revolution onwards, large-scale anthropogenic greenhouse gas emissions caused the Earth to warm. Likewise, climatic changes have induced substantial changes in human civilisation over the course of the Holocene.

During the transition from the last glacial to the Holocene, the Huelmo–Mascardi Cold Reversal in the Southern Hemisphere began before the Younger Dryas, and the maximum warmth flowed south to north from 11,000 to 7,000 years ago. It appears that this was influenced by the residual glacial ice remaining in the Northern Hemisphere until the later date. The first major phase of Holocene climate was the Preboreal. At the start of the Preboreal occurred the Preboreal Oscillation (PBO). The Holocene Climatic Optimum (HCO) was a period of warming throughout the globe but was not globally synchronous and uniform. Following the HCO, the global climate entered a broad trend of very gradual cooling known as Neoglaciation, which lasted from the end of the HCO to before the Industrial Revolution. From the 10th-14th century, the climate was similar to that of modern times during a period known as the Mediaeval Warm Period (MWP), also known as the Mediaeval Climatic Optimum (MCO). It was found that the warming that is taking place in current years is both more frequent and more spatially homogeneous than what was experienced during the MWP. A warming of +1 degree Celsius occurs 5–40 times more frequently in modern years than during the MWP. The major forcing during the MWP was due to greater solar activity, which led to heterogeneity compared to the greenhouse gas forcing of modern years that leads to more homogeneous warming. This was followed by the Little Ice Age (LIA) from the 13th or 14th century to the mid-19th century. The LIA was the coldest interval of time of the past two millennia. Following the Industrial Revolution, warm decadal intervals became more common relative to before as a consequence of anthropogenic greenhouse gases, resulting in progressive global warming. In the late 20th century, anthropogenic forcing superseded solar activity as the dominant driver of climate change, though solar activity has continued to play a role.

Europe
Drangajökull, Iceland's northernmost glacier, melted shortly after 9,200 BP. In Northern Germany, the Middle Holocene saw a drastic increase in the amount of raised bogs, most likely related to sea level rise. Although human activity affected geomorphology and landscape evolution in Northern Germany throughout the Holocene, it only became a dominant influence in the last four centuries. In the French Alps, geochemistry and lithium isotope signatures in lake sediments have suggested gradual soil formation from the Last Glacial Period to the Holocene climatic optimum, and this soil development was altered by the settlement of human societies. Early anthropogenic activities such as deforestation and agriculture reinforced soil erosion, which peaked in the Middle Ages at an unprecedented level, marking human forcing as the most powerful factor affecting surface processes. The sedimentary record from Aitoliko Lagoon indicates that wet winters locally predominated from 210 to 160 BP, followed by dry winter dominance from 160 to 20 BP.

Africa
North Africa, dominated by the Sahara Desert in the present, was instead a savanna dotted with large lakes during the Early and Middle Holocene, regionally known as the African Humid Period (AHP). The northward migration of the Intertropical Convergence Zone (ITCZ) produced increased monsoon rainfall over North Africa. The lush vegetation of the Sahara brought an increase in pastoralism. The AHP ended around 5,500 BP, after which the Sahara began to dry and become the desert it is today.

A stronger East African Monsoon during the Middle Holocene increased precipitation in East Africa and raised lake levels. Around 800 AD, or 1,150 BP, a marine transgression occurred in southeastern Africa; in the Lake Lungué basin, this sea level highstand occurred from 740 to 910 AD, or from 1,210 to 1,040 BP, as evidenced by the lake's connection to the Indian Ocean at this time. This transgression was followed by a period of transition that lasted until 590 BP, when the region experienced significant aridification and began to be extensively used by humans for livestock herding.

In the Kalahari Desert, Holocene climate was overall very stable and environmental change was of low amplitude. Relatively cool conditions have prevailed since 4,000 BP.

Middle East
During the Late Holocene, the coastline of the Levant receded westward, prompting a shift in human settlement patterns following this marine regression.

Central Asia
Central Asia experienced glacial-like temperatures until about 8,000 BP, when the Laurentide Ice Sheet collapsed. In Xinjiang, long-term Holocene warming increased meltwater supply during summers, creating large lakes and oases at low altitudes and inducing enhanced moisture recycling. In the Tien Shan, sedimentological evidence from Swan Lake suggests the period between 8,500 and 6,900 BP was relatively warm, with steppe meadow vegetation being predominant. An increase in Cyperaceae from 6,900 to 2,600 BP indicates cooling and humidification of the Tian Shan climate that was interrupted by a warm period between 5,500 and 4,500 BP. After 2,600 BP, an alpine steppe climate prevailed across the region. Sand dune evolution in the Bayanbulak Basin shows that the region was very dry from the Holocene's beginning until around 6,500 BP, when a wet interval began. In the Tibetan Plateau, the moisture optimum spanned from around 7,500 to 5,500 BP. The Tarim Basin records the onset of significant aridification around 3,000-2,000 BP.

South Asia
After 11,800 BP, and especially between 10,800 and 9,200 BP, Ladakh experienced tremendous moisture increase most likely related to the strengthening of the Indian Summer Monsoon (ISM). From 9,200 to 6,900 BP, relative aridity persisted in Ladakh. A second major humid phase occurred in Ladakh from 6,900 to 4,800 BP, after which the region was again arid.

From 900 to 1,200 AD, during the MWP, the ISM was again strong as evidenced by low δ18O values from the Ganga Plain.

The sediments of Lonar Lake in Maharashtra record dry conditions around 11,400 BP that transitioned into a much wetter climate from 11,400 to 11,100 BP due to intensification of the ISM. Over the Early Holocene, the region was very wet, but during the Middle Holocene from 6,200 to 3,900 BP, aridification occurred, with the subsequent Late Holocene being relatively arid as a whole.

Coastal southwestern India experienced a stronger ISM from 9,690 to 7,560 BP, during the HCO. From 3,510 to 2,550 BP, during the Late Holocene, the ISM became weaker, although this weakening was interrupted by an interval of unusually high ISM strength from 3,400 to 3,200 BP.

East Asia
Southwestern China experienced long-term warming during the Early Holocene up until ~7,000 BP. Northern China experienced an abrupt aridification event approximately 4,000 BP. From around 3,500 to 3,000 BP, northeastern China underwent a prolonged cooling, manifesting itself with the disruption of Bronze Age civilisations in the region. Eastern and southern China, the monsoonal regions of China, were wetter than present in the Early and Middle Holocene. Lake Huguangyan's TOC, δ13Cwax, δ13Corg, δ15N values suggest the period of peak moisture lasted from 9,200 to 1,800 BP and was attributable to a strong East Asian Summer Monsoon (EASM). Late Holocene cooling events in the region were dominantly influenced by solar forcing, with many individual cold snaps linked to solar minima such as the Oort, Wolf, Spörer, and Maunder Minima. A notable cooling event in southeastern China occurred 3,200 BP. Strengthening of the winter monsoon occurred around 5,500, 4,000, and 2,500 BP. Monsoonal regions of China became more arid in the Late Holocene.

Southeast Asia
Before 7,500 BP, the Gulf of Thailand was exposed above sea level and was very arid. A marine transgression occurred from 7,500 to 6,200 BP amidst global warming.

North America
During the Middle Holocene, western North America was drier than present, with wetter winters and drier summers. After the end of the thermal maximum of the HCO around 4,500 BP, the East Greenland Current underwent strengthening. A massive megadrought occurred from 2,800 to 1,850 BP in the Great Basin.

Eastern North America underwent abrupt warming and humidification around 10,500 BP and then declined from 9,300 to 9,100 BP. The region has undergone a long term wettening since 5,500 BP occasionally interrupted by intervals of high aridity. A major cool event lasting from 5,500 to 4,700 BP was coeval with a major humidification before being terminated by a major drought and warming at the end of that interval.

South America
During the Early Holocene, relative sea level rose in the Bahia region, causing a landward expansion of mangroves. During the Late Holocene, the mangroves declined as sea level dropped and freshwater supply increased. In the Santa Catarina region, the maximum sea level highstand was around 2.1 metres above present and occurred about 5,800 to 5,000 BP. Sea levels at Rocas Atoll were likewise higher than present for much of the Late Holocene.

Australia
The Northwest Australian Summer Monsoon was in a strong phase from 8,500 to 6,400 BP, from 5,000 to 4,000 BP (possibly until 3,000 BP), and from 1,300 to 900 BP, with weak phases in between and the current weak phase beginning around 900 BP after the end of the last strong phase.

New Zealand
Ice core measurements imply that the sea surface temperature (SST) gradient east of New Zealand, across the subtropical front (STF), was around 2 degrees Celsius during the HCO. This temperature gradient is significantly less than modern times, which is around 6 degrees Celsius. A study utilizing five SST proxies from 37°S to 60°S latitude confirmed that the strong temperature gradient was confined to the area immediately south of the STF, and is correlated with reduced westerly winds near New Zealand. Since 7,100 BP, New Zealand experienced 53 cyclones similar in magnitude to Cyclone Bola.

Pacific
Evidence from the Galápagos Islands shows that the El Niño–Southern Oscillation (ENSO) was significantly weaker during the Middle Holocene, but that the strength of ENSO became moderate to high over the Late Holocene.

Ecological developments
Animal and plant life have not evolved much during the relatively short Holocene, but there have been major shifts in the richness and abundance of plants and animals. A number of large animals including mammoths and mastodons, saber-toothed cats like Smilodon and Homotherium, and giant sloths went extinct in the late Pleistocene and early Holocene. These extinctions can be mostly attributed to people. In America, it coincided with the arrival of the Clovis people; this culture was known for "Clovis points" which were fashioned on spears for hunting animals. Shrubs, herbs, and mosses had also changed in relative abundance from the Pleistocene to Holocene, identified by permafrost core samples.

Throughout the world, ecosystems in cooler climates that were previously regional have been isolated in higher altitude ecological "islands".

The 8.2-ka event, an abrupt cold spell recorded as a negative excursion in the record lasting 400 years, is the most prominent climatic event occurring in the Holocene Epoch, and may have marked a resurgence of ice cover. It has been suggested that this event was caused by the final drainage of Lake Agassiz, which had been confined by the glaciers, disrupting the thermohaline circulation of the Atlantic. This disruption was the result of an ice dam over Hudson Bay collapsing sending cold lake Agassiz water into the North Atlantic ocean. Furthermore, studies show that the melting of Lake Agassiz led to sea-level rise which flooded the North American coastal landscape. The basal peat plant was then used to determine the resulting local sea-level rise of 0.20-0.56m in the Mississippi Delta. Subsequent research, however, suggested that the discharge was probably superimposed upon a longer episode of cooler climate lasting up to 600 years and observed that the extent of the area affected was unclear.

Human developments

The beginning of the Holocene corresponds with the beginning of the Mesolithic age in most of Europe. In regions such as the Middle East and Anatolia, the term Epipaleolithic is preferred in place of Mesolithic, as they refer to approximately the same time period. Cultures in this period include Hamburgian, Federmesser, and the Natufian culture, during which the oldest inhabited places still existing on Earth were first settled, such as Tell es-Sultan (Jericho) in the Middle East. There is also evolving archeological evidence of proto-religion at locations such as Göbekli Tepe, as long ago as the 9th millennium BC.

The preceding period of the Late Pleistocene had already brought advancements such as the bow and arrow, creating more efficient forms of hunting and replacing spear throwers. In the Holocene, however, the domestication of plants and animals allowed humans to develop villages and towns in centralized locations. Archaeological data shows that between 10,000 and 7,000 BP rapid domestication of plants and animals took place in tropical and subtropical parts of Asia, Africa, and Central America. The development of farming allowed humans to transition away from hunter-gatherer nomadic cultures, which did not establish permanent settlements, to a more sustainable sedentary lifestyle. This form of lifestyle change allowed humans to develop towns and villages in centralized locations, which gave rise to the world known today. It is believed that the domestication of plants and animals began in the early part of the Holocene in the tropical areas of the planet. Because these areas had warm, moist temperatures, the climate was perfect for effective farming. Culture development and human population change, specifically in South America, has also been linked to spikes in hydroclimate resulting in climate variability in the mid-Holocene (8.2 - 4.2 k cal BP). Climate change on seasonality and available moisture also allowed for favorable agricultural conditions which promoted human development for Maya and Tiwanaku regions. In the Korean Peninsula, climatic changes fostered a population boom during the Middle Chulmun period from 5,500 to 5,000 BP, but contributed to a subsequent bust during the Late and Final Chulmun periods, from 5,000 to 4,000 BP and from 4,000 to 3,500 BP respectively.

Extinction event
The Holocene extinction, otherwise referred to as the sixth mass extinction or Anthropocene extinction, is an ongoing extinction event of species during the present Holocene epoch (with the more recent time sometimes called Anthropocene) as a result of human activity. The included extinctions span numerous families of fungi, plants, and animals, including mammals, birds, reptiles, amphibians, fish and invertebrates. With widespread degradation of highly biodiverse habitats such as coral reefs and rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, or no one has yet discovered their extinction. The current rate of extinction of species is estimated at 100 to 1,000 times higher than natural background extinction rates.

title: Holocene


text:
Harbor

A harbor (American English), or harbour (Canadian English, British English; see spelling differences), is a sheltered body of water where ships, boats, and barges can be moored. The term harbor is often used interchangeably with port, which is a man-made facility built for loading and unloading vessels and dropping off and picking up passengers. Harbors usually include one or more ports. Alexandria Port in Egypt, meanwhile, is an example of a port with two harbors.

Harbors may be natural or artificial. An artificial harbor can have deliberately constructed breakwaters, sea walls, or jetties or they can be constructed by dredging, which requires maintenance by further periodic dredging. An example of an artificial harbor is Long Beach Harbor, California, United States, which was an array of salt marshes and tidal flats too shallow for modern merchant ships before it was first dredged in the early 20th century. In contrast, a natural harbor is surrounded on several sides by land. Examples of natural harbors include Sydney Harbour, New South Wales, Australia, Halifax Harbour in Halifax, Nova Scotia, Canada and Trincomalee Harbour in Sri Lanka.

Artificial harbors
Artificial harbors are frequently built for use as ports. The oldest artificial harbor known is the Ancient Egyptian site at Wadi al-Jarf, on the Red Sea coast, which is at least 4500 years old (ca. 2600-2550 BCE, reign of King Khufu). The largest artificially created harbor is Jebel Ali in Dubai. Other large and busy artificial harbors include:

 * Port of Houston, Texas, United States
 * Port of Long Beach, California, United States
 * Port of Los Angeles in San Pedro, California, United States
 * Port of Rotterdam, Netherlands
 * Port of Savannah, Georgia, United States

The Ancient Carthaginians constructed fortified, artificial harbors called cothons.

Natural harbors
A natural harbor is a landform where a section of a body of water is protected and deep enough to allow anchorage. Many such harbors are rias. Natural harbors have long been of great strategic naval and economic importance, and many great cities of the world are located on them. Having a protected harbor reduces or eliminates the need for breakwaters as it will result in calmer waves inside the harbor. Some examples are:

 * Bali Strait, Indonesia
 * Berehaven Harbour, Ireland
 * Balikpapan Bay in East Kalimantan, Indonesia
 * Mumbai in Maharashtra, India
 * Boston Harbor in Massachusetts, United States
 * Burrard Inlet in Vancouver, British Columbia, Canada
 * Chittagong in Chittagong Division, Bangladesh
 * Cork Harbour, Ireland
 * Grand Harbour, Malta
 * Guantánamo Bay, Cuba
 * Gulf of Paria, Trinidad and Tobago
 * Haifa Bay, in Haifa, Israel
 * Halifax Harbour in Nova Scotia, Canada
 * Hamilton Harbour in Ontario, Canada
 * Killybegs in County Donegal, Ireland
 * Kingston Harbour, Jamaica
 * Mahón harbour, in Menorca, Spain
 * Marsamxett Harbour, Malta
 * Milford Haven in Wales, United Kingdom
 * New York Harbor in the United States
 * Pago Pago Harbor in American Samoa
 * Pearl Harbor in Hawaii, United States
 * Poole Harbour in England, United Kingdom
 * Port Hercules, Monaco
 * Sydney Harbour in New South Wales, Australia, technically a ria
 * Port Stephens in Australia
 * Tanjung Perak in Surabaya, Indonesia
 * Port of Tobruk in Tobruk, Libya
 * Presque Isle Bay in Pennsylvania, United States
 * Prince William Sound in Alaska, United States
 * Puget Sound in Washington state, United States
 * Rías Altas and Rías Baixas in Galicia, Spain
 * Roadstead of Brest in Brittany, France
 * San Francisco Bay in California, United States
 * Scapa Flow in Scotland, United Kingdom
 * Sept-Îles in Côte-Nord, Quebec, Canada
 * Shelburne in Nova Scotia, Canada
 * Subic Bay in Zambales, Philippines
 * Tallinn Bay in Tallinn, Estonia
 * Tampa Bay in Florida, United States
 * Trincomalee Harbour, Sri Lanka
 * Tuticorin in Tamil Nadu, India
 * Victoria Harbour in Hong Kong
 * Visakhapatnam Harbour, India
 * Vizhinjam in Trivandrum, India
 * Waitemata Harbour in Auckland, New Zealand
 * Manukau Harbour in Auckland, New Zealand
 * Port Foster in Deception Island, Antarctica

Ice-free harbors
For harbors near the North and South poles, being ice-free is an important advantage, especially when it is year-round. Examples of these are:

 * Hammerfest, Norway
 * Liinakhamari, Russia
 * Murmansk, Russia
 * Nakhodka in Nakhodka Bay, Russia
 * Pechenga, Russia
 * Prince Rupert, Canada
 * Valdez, United States
 * Vardø, Norway
 * Vostochny Port, Russia

The world's southernmost harbor, located at Antarctica's Winter Quarters Bay (77° 50′ South), is sometimes ice-free, depending on the summertime pack ice conditions.

Important harbors

Although the world's busiest port is a contested title, in 2017 the world's busiest harbor by cargo tonnage was the Port of Ningbo-Zhoushan.

The following are large natural harbors: • Algeciras, Spain

• Amsterdam, Port of Amsterdam, Netherlands

• Antwerp, Port of Antwerp, Belgium

• Baltimore's Inner Harbor, Maryland, United States

• Botwood, Newfoundland, Canada

• Bremerhaven, Germany

• Buenos Aires, Argentina

• Busan, South Korea

• Calabar, Nigeria

• Cartagena, Colombia

• Charleston, South Carolina, United States

• Chennai, Tamil Nadu, India

• Cochin Port, Kochi, Kerala, India

• Port of Chittagong, Chittagong, Bangladesh

• Dnipro, Ukraine

• Durban, South Africa

• Falmouth, Cornwall, England, United Kingdom

• Freetown Harbour, Sierra Leone

• Golden Horn, Istanbul, Turkey

• Gothenburg, Sweden

• Gwangyang, South Korea

• Hai Phong Port, Haiphong, Vietnam

• Haifa, Israel

• Hakodate, Japan

• Halifax Harbour, Nova Scotia, Canada

• Hamburg Harbour, Germany

• Hampton Roads, Norfolk, Virginia, United States

• Havana Harbor

• Helsinki, Finland

• Incheon, South Korea

• İzmir, Turkey

• Port of Jakarta (Tanjung Priok), Jakarta, Indonesia

• Kaliningrad, Russia

• Karachi, Sindh, Pakistan

• Kerch and Port Krym to Port Kavkaz, Russia

• Kyiv, Ukraine

• Kingston, Jamaica

• Kobe Harbour, Kobe, Japan

• Port of Kolkata, Kolkata, West Bengal, India

• Port of Lisbon, Lisbon, Portugal

• Lushunkou, Dalian, China

• Mahón, Menorca, Spain

• Manila Bay, Philippines

• Maputo, Mozambique

• Milford Haven, Wales, United Kingdom

• Milwaukee, Wisconsin

• Montevideo, Uruguay

• Mumbai, India

• Nassau, Bahamas

• New York Harbor, United States

• Mykolaiv, Ukraine

• Novorossiysk and Anapa, Russia

• Odesa, Ukraine

• Osaka, Japan

• Oslofjord and Oslo, Norway

• Pärnu, Estonia

• Plymouth Sound, Devon, England, United Kingdom

• Port of Portland, Casco Bay, Maine, United States

• Port of Sevastopol, Sevastopol, Crimea

• Port Phillip, Melbourne, Victoria, Australia

• Provincetown Harbor, Provincetown, Massachusetts, United States

• Rio de Janeiro, Guanabara Bay, Brazil

• Rostov-on-Don, Russia

• Rotterdam, Port of Rotterdam, Netherlands

• Salvador, All Saint's Bay, Brazil

• San Antonio, Chile

• San Diego Bay, San Diego, California, United States

• Saint Petersburg, Russia

• Sochi and Adlersky City District, Russia

• Stockholm, Sweden

• Tallinn, Estonia

• Tanger-Med, Tangier, Morocco

• Tanjung Perak, Surabaya, Indonesia

• Tauranga Harbour, Tauranga, New Zealand

• Tokyo Bay, Tokyo, Japan

• Trincomalee, Sri Lanka

• Tuticorin, Tamil Nadu, India

• Port of Tyne, Tyne & Wear, United Kingdom

• Ulsan, South Korea

• Victoria & Esquimalt Harbours, Victoria, British Columbia, Canada

• Victoria Harbour (Hong Kong)

• Vizhinjam in Trivandrum, India

• Vladivostok, Russia

• Vyborg, Russia

• Willemstad, Curaçao

• Wellington Harbour, New Zealand

• Yevpatoria, Ukraine

• Zaporizhzhia, Ukraine

title: Harbor


text:
High anxiety

High anxiety is a non-technical term referring to a state of extreme fear or apprehension. It may also mean:

 * High Anxiety, a 1977 film by Mel Brooks
 * High Anxiety (Therapy? album), 2003
 * High Anxiety (Thom Sonny Green album), 2016
 * High Anxiety, a 2014 album by Pet Lamb (recorded in 1995)
 * "High Anxiety", a song on the A Match and Some Gasoline album by The Suicide Machines
 * "High Anxiety", a song from Sugar Ray's album Floored
 * "High Anxiety" (Part 2), an episode of King of the Hill
 * "High Anxiety", an episode of Kate & Allie
 * "High Anxiety", The Golden Girls episode
 * "High Anxiety", a Dawson's Creek episode
 * "High Anxiety", an episode of 7th Heaven
 * "High Anxiety", an episode of A Different World
 * "High Anxiety", an episode of Full House
 * "Episode 3: High Anxiety", an episode from Rayman: The Animated Series
 * "High Anxiety", an episode from Rescue Heroes (originally named Terror In The Tower, but retitled after the September 11 attack, then got banned from Teletoon shortly after)

title: High anxiety


text:
H

H, or h, is the eighth letter of the Latin alphabet, used in the modern English alphabet, including the alphabets of other western European languages and others worldwide. Its name in English is aitch (pronounced, plural aitches), or regionally haitch , plural haitches.

English
For most English speakers, the name for the letter is pronounced as and spelled "aitch" or occasionally "eitch". The pronunciation and the associated spelling "haitch" are often considered to be h-adding and are considered non-standard in England. It is, however, a feature of Hiberno-English, and occurs sporadically in various other dialects.

The perceived name of the letter affects the choice of indefinite article before initialisms beginning with H: for example "an H-bomb" or "a H-bomb". The pronunciation may be a hypercorrection formed by analogy with the names of the other letters of the alphabet, most of which include the sound they represent.

The haitch pronunciation of h has spread in England, being used by approximately 24% of English people born since 1982, and polls continue to show this pronunciation becoming more common among younger native speakers. Despite this increasing number, the pronunciation without the sound is still considered standard in England, although the pronunciation with  is also attested as a legitimate variant. In Northern Ireland, the pronunciation of the letter has been used as a shibboleth, with Catholics typically pronouncing it with the and Protestants pronouncing the letter without it.

Authorities disagree about the history of the letter's name. The Oxford English Dictionary says the original name of the letter was in Latin; this became  in Vulgar Latin, passed into English via Old French, and by Middle English was pronounced. The American Heritage Dictionary of the English Language derives it from French hache from Latin haca or hic. Anatoly Liberman suggests a conflation of two obsolete orderings of the alphabet, one with H immediately followed by K and the other without any K: reciting the former's ..., H, K, L,... as when reinterpreted for the latter ..., H, L,... would imply a pronunciation of  for H.

Other languages

 * French: ache
 * German: ha
 * Portuguese: agá
 * Spanish: hache

History
The original Semitic letter Heth most likely represented the voiceless pharyngeal fricative. The form of the letter probably stood for a fence or posts.

The Greek Eta 'Η' in archaic Greek alphabets, before coming to represent a long vowel,, still represented a similar sound, the voiceless glottal fricative. In this context, the letter eta is also known as Heta. Thus, in the Old Italic alphabets, the letter Heta of the Euboean alphabet was adopted with its original sound value.

While Etruscan and Latin had as a phoneme, almost all Romance languages lost the sound—Romanian later re-borrowed the  phoneme from its neighbouring Slavic languages, and Spanish developed a secondary  from, before losing it again; various Spanish dialects have developed  as an allophone of  or  in most Spanish-speaking countries, and various dialects of Portuguese use it as an allophone of. 'H' is also used in many spelling systems in digraphs and trigraphs, such as 'ch', which represents in Spanish, Galician, and Old Portuguese;  in French and modern Portuguese;  in Italian and French.

English
In English, $⟨h⟩$ occurs as a single-letter grapheme (being either silent or representing the voiceless glottal fricative and in various digraphs: The letter is silent in a syllable rime, as in ah, ohm, dahlia, cheetah, and pooh-poohed, as well as in certain other words (mostly of French origin) such as hour, honest, herb (in American but not British English) and vehicle (in certain varieties of English). Initial  is often not pronounced in the weak form of some function words, including had, has, have, he, her, him, his, and in some varieties of English (including most regional dialects of England and Wales), it is often omitted in all words. It was formerly common for an rather than a to be used as the indefinite article before a word beginning with  in an unstressed syllable, as in "an historian", but the use of a is now more usual.
 * $⟨h⟩$ representing, , , or
 * $⟨ch⟩$ being silent or representing, , , or
 * $⟨gh⟩$ representing
 * $⟨ph⟩$ representing
 * $⟨rh⟩$ representing
 * $⟨sh⟩$ representing or
 * $⟨th⟩$ representing or

In English, the pronunciation of $⟨wh⟩$ as /h/ can be analyzed as a voiceless vowel. That is, when the phoneme /h/ precedes a vowel, /h/ may be realized as a voiceless version of the subsequent vowel. For example, the word $⟨h⟩$, /hɪt/ is realized as [ɪ̥ɪt].

H is the eighth most frequently used letter in the English language (after S, N, I, O, A, T, and E), with a frequency of about 4.2% in words.

Other languages
In German, following a vowel, it often silently indicates that the vowel is long: In the word erhöhen ('heighten'), the second $⟨hit⟩$ is mute for most speakers outside of Switzerland. In 1901, a spelling reform eliminated the silent $⟨h⟩$ in nearly all instances of $⟨h⟩$ in native German words such as thun ('to do') or Thür ('door'). It has been left unchanged in words derived from Greek, such as Theater ('theater') and Thron ('throne'), which continue to be spelled with $⟨th⟩$ even after the last German spelling reform.

In Spanish and Portuguese, $⟨th⟩$ is a silent letter with no pronunciation, as in hijo ('son') and húngaro  ('Hungarian'). The spelling reflects an earlier pronunciation of the sound. In words where the $⟨h⟩$ is derived from a Latin, it is still sometimes pronounced with the value in some regions of Andalusia, Extremadura, Canarias, Cantabria, and the Americas. Some words beginning with or, such as hielo and huevo, were given an initial $⟨h⟩$ to avoid confusion between their initial semivowels and the consonants $⟨h⟩$ and $⟨j⟩$. This is because $⟨v⟩$ and $⟨j⟩$ used to be considered variants of $⟨v⟩$ and $⟨i⟩$ respectively. $⟨u⟩$ also appears in the digraph $⟨h⟩$, which represents in Spanish and northern Portugal, and  in varieties that have merged both sounds (the latter originally represented by $⟨ch⟩$ instead), such as most of the Portuguese language and some Spanish dialects, prominently Chilean Spanish.

French orthography classifies words that begin with this letter in two ways, one of which can affect the pronunciation, even though it is a silent letter either way. The H muet, or "mute" $⟨x⟩$, is considered as though the letter were not there at all. For example, the singular definite article le or la, which is elided to l' before a vowel, elides before an H muet followed by a vowel. For example, le + hébergement becomes l'hébergement ('the accommodation'). The other kind of $⟨h⟩$ is called h aspiré ("aspirated '$⟨h⟩$'", though it is not normally aspirated phonetically), and does not allow elision or liaison. For example, in le homard ('the lobster') the article le remains unelided, and may be separated from the noun with a bit of a glottal stop. Most words that begin with an H muet come from Latin (honneur, homme) or from Greek through Latin (hécatombe), whereas most words beginning with an H aspiré come from Germanic (harpe, hareng) or non-Indo-European languages (harem, hamac, haricot); in some cases, an orthographic $⟨h⟩$ was added to disambiguate the and semivowel  pronunciations before the introduction of the distinction between the letters $⟨h⟩$ and $⟨v⟩$: huit (from uit, ultimately from Latin octo), huître (from uistre, ultimately from Greek through Latin ostrea).

In Italian, $⟨u⟩$ has no phonological value. Its most important uses are in the digraphs 'ch' and 'gh', as well as to differentiate the spellings of certain short words that are homophones, for example, some present tense forms of the verb avere ('to have') (such as hanno, 'they have', vs. anno, 'year'), and in short interjections (oh, ehi).

Some languages, including Czech, Slovak, Hungarian, Finnish, and Estonian, use $⟨h⟩$ as a breathy voiced glottal fricative, often as an allophone of otherwise voiceless in a voiced environment.

In Hungarian, the letter represents a phoneme with four allophones:  before vowels,  between two vowels,  after front vowels, and  word-finally after back vowels. It can also be a silent word-finally after back vowels. It is when geminated. In archaic spelling, the digraph $⟨h⟩$ represents (as in the name Széchenyi) and  (as in pech, which is pronounced ); in certain environments it breaks palatalization of a consonant, as in the name Beöthy, which is pronounced  (without the intervening h, the name Beöty could be pronounced ); and finally, it acts as a silent component of a digraph, as in the name Vargha, pronounced.

In Ukrainian and Belarusian, when written in the Latin alphabet, $⟨ch⟩$ is also commonly used for, which is otherwise written with the Cyrillic letter $⟨h⟩$.

In Irish, $⟨г⟩$ is not considered an independent letter, except for a very few non-native words; however, $⟨h⟩$ placed after a consonant is known as a "séimhiú" and indicates the lenition of that consonant; $⟨h⟩$ began to replace the original form of a séimhiú, a dot placed above the consonant, after the introduction of typewriters.

In most dialects of Polish, both $⟨h⟩$ and the digraph $⟨h⟩$ always represent.

In Basque, during the 20th century, it was not used in the orthography of the Basque dialects in Spain but it marked an aspiration in the North-Eastern dialects. During the standardization of Basque in the 1970s, a compromise was reached that h would be accepted if it were the first consonant in a syllable. Hence, herri ("people") and etorri ("to come") were accepted instead of erri (Biscayan) and ethorri (Souletin).

Other systems
As a phonetic symbol in the International Phonetic Alphabet (IPA), it is used mainly for the so-called aspirations (fricative or trills), and variations of the plain letter are used to represent two sounds: the lowercase form represents the voiceless glottal fricative, and the small capital form  represents the voiceless epiglottal fricative (or trill). With a bar, minuscule is used for a voiceless pharyngeal fricative. Specific to the IPA, a hooked is used for a voiced glottal fricative, and a superscript  is used to represent aspiration.

Other uses

 * Unit prefix h, meaning 100 times.

Descendants and related characters in the Latin alphabet

 * H with diacritics: Ĥ|Ĥ ĥ Ȟ|Ȟ ȟ Ħ|Ħ ħ Ḩ ḩ Ⱨ|Ⱨ ⱨ ẖ ẖ Ḥ ḥ Ḣ ḣ Ḧ|Ḧ ḧ Ḫ|Ḫ ḫ ꞕ Ꜧ ꜧ
 * IPA-specific symbols related to H:
 * Superscript IPA symbols related to H: 𐞖 𐞕
 * ꟸ: Modifier letter capital H with stroke is used in VoQS to represent faucalized voice.
 * ᴴ : Modifier letter H is used in the Uralic Phonetic Alphabet
 * ₕ : Subscript small h was used in the Uralic Phonetic Alphabet prior to its formal standardization in 1902
 * ʰ : Modifier letter small h is used in Indo-European studies
 * ʮ and ʯ : Turned H with fishhook and turned H with fishhook and tail are used in Sino-Tibetanist linguistics
 * Ƕ ƕ : Latin letter hwair, derived from a ligature of the digraph hv, and used to transliterate the Gothic letter 𐍈 (which represented the sound [hʷ])
 * Ⱶ ⱶ : Claudian letters
 * Ꟶ ꟶ : Reversed half h used in Roman inscriptions from the Roman provinces of Gaul

Ancestors, siblings, and descendants in other alphabets

 * 𐤇 : Semitic letter Heth, from which the following symbols derive:
 * Η η : Greek letter Eta, from which the following symbols derive:
 * 𐌇 : Old Italic H, the ancestor of modern Latin H
 * : Runic letter haglaz, which is probably a descendant of Old Italic H
 * Һ һ : Cyrillic letter Shha, which derives from Latin H
 * И и : Cyrillic letter И, which derives from the Greek letter Eta
 * : Gothic letter haal
 * Armenian letter ho (Հ)

Derived signs, symbols, and abbreviations

 * $h$ : Planck constant
 * ℏ : reduced Planck constant
 * $$\mathbb{H}$$ : Blackboard bold capital H used in quaternion notation

Computing
1 Also for encodings based on ASCII, including the DOS, Windows, ISO-8859, and Macintosh families of encodings.

title: H


text:
HCI

HCI may refer to:

Computing

 * Happy Computers, an American computer hardware manufacturer
 * Home Computer Initiative, a United Kingdom government programme to increase computers usage
 * Host controller interface (disambiguation), various computer interfaces
 * Human–computer interaction, the study of how people interact with computers
 * Human-computer interaction (security), the study of how people interact with computers concerning information security
 * Hyper-converged infrastructure, an IT infrastructure framework for integrating storage, networking and virtualization computing in a data center.

Education

 * Harbord Collegiate Institute, a school in Toronto, Canada
 * Humberside Collegiate Institute, a school in Toronto, Canada
 * Hwa Chong Institution, a school in Singapore

Science

 * Highly charged ion
 * Hot carriers injection, in solid-state electronic devices
 * Hydrocarbon indicator, in reflection seismology

Organizations

 * Handgun Control, Inc., the former name of the Brady Campaign to Prevent Gun Violence
 * Harrisburg City Islanders, a soccer club from the United States
 * HCI Books (Health Communications Inc), an American publishing house, see What the Bleep Do We Know!?
 * Human Concern International, a Canadian relief and development organization
 * Huntsman Cancer Institute, an American cancer research facility and hospital

Other uses

 * Heavy-Chemical Industry Drive, a former economic development plan of South Korea

title: HCI


text:
Horseshoe

A horseshoe is a product designed to protect a horse hoof from wear. Shoes are attached on the palmar surface (ground side) of the hooves, usually nailed through the insensitive hoof wall that is anatomically akin to the human toenail, although much larger and thicker. However, there are also cases where shoes are glued.

Horseshoes are available in a wide variety of materials and styles, developed for different types of horses and for the work they do. The most common materials are steel and aluminium, but specialized shoes may include use of rubber, plastic, magnesium, titanium, or copper. Steel tends to be preferred in sports in which a strong, long-wearing shoe is needed, such as polo, eventing, show jumping, and western riding events. Aluminium shoes are lighter, making them common in horse racing where a lighter shoe is desired, and often facilitate certain types of movement; they are often favored in the discipline of dressage. Some horseshoes have "caulkins", "caulks", or "calks": protrusions at the toe or heels of the shoe, or both, to provide additional traction.

The fitting of horseshoes is a professional occupation, conducted by a farrier, who specializes in the preparation of feet, assessing potential lameness issues, and fitting appropriate shoes, including remedial features where required. In some countries, such as the UK, horseshoeing is legally restricted to people with specific qualifications and experience. In others, such as the United States, where professional licensing is not legally required, professional organizations provide certification programs that publicly identify qualified individuals.

When kept as a talisman, a horseshoe is said to bring good luck. A stylized variation of the horseshoe is used for a popular throwing game, horseshoes.

History
Since the early history of domestication of the horse, working animals were found to be exposed to many conditions that created breakage or excessive hoof wear. Ancient people recognized the need for the walls (and sometimes the sole) of domestic horses' hooves to have additional protection over and above any natural hardness. An early form of hoof protection was seen in ancient Asia, where horses' hooves were wrapped in rawhide, leather, or other materials for both therapeutic purposes and protection from wear. From archaeological finds in Great Britain, the Romans appeared to have attempted to protect their horses' feet with a strap-on, solid-bottomed "hipposandal" that has a slight resemblance to the modern hoof boot.

Historians differ on the origin of the horseshoe. Because iron was a valuable commodity, and any worn out items were generally reforged and reused, it is difficult to locate clear archaeological evidence. Although some credit the Druids, there is no hard evidence to support this claim. In 1897 four bronze horseshoes with what are apparently nail holes were found in an Etruscan tomb dated around 400 BC. The assertion by some historians that the Romans invented the "mule shoes" sometime after 100 BC is supported by a reference by Catullus who died in 54 BC. However, these references to use of horseshoes and muleshoes in Rome may have been to the "hipposandal"—leather boots, reinforced by an iron plate, rather than to nailed horseshoes.

Existing references to the nailed shoe are relatively late, first known to have appeared around AD 900, but there may have been earlier uses given that some have been found in layers of dirt. There are no extant references to nailed horseshoes prior to the reign of Byzantine Emperor Leo VI, and by 973 occasional references to them can be found. The earliest clear written record of iron horseshoes is a reference to "crescent figured irons and their nails" in AD 910. There is very little evidence of any sort that suggests the existence of nailed-on shoes prior to AD 500 or 600, though there is a find dated to the fifth century AD of a horseshoe, complete with nails, found in the tomb of the Frankish King Childeric I at Tournai, Belgium.

Around 1000 AD, cast bronze horseshoes with nail holes became common in Europe. A design with a scalloped outer rim and six nail holes was common. According to Gordon Ward the scalloped edges were created by double punching the nail holes causing the edges to bulge. The 13th and 14th centuries brought the widespread manufacturing of iron horseshoes. By the time of the Crusades (1096–1270), horseshoes were widespread and frequently mentioned in various written sources. In that period, due to the value of iron, horseshoes were even accepted in lieu of coin to pay taxes.

By the 13th century, shoes were forged in large quantities and could be bought ready made. Hot shoeing, the process of shaping a heated horseshoe immediately before placing it on the horse, became common in the 16th century. From the need for horseshoes, the craft of blacksmithing became "one of the great staple crafts of medieval and modern times and contributed to the development of metallurgy." A treatise titled "No Foot, No Horse" was published in England in 1751.

In 1835, the first U.S. patent for a horseshoe manufacturing machine capable of making up to 60 horseshoes per hour was issued to Henry Burden. In mid-19th-century Canada, marsh horseshoes kept horses from sinking into the soft intertidal mud during dike-building. In a common design, a metal horseshoe holds a flat wooden shoe in place.

China
In China, iron horseshoes became common during the Yuan dynasty (1271–1368), prior to which rattan and leather shoes were used to preserve animal hooves. Evidence of the preservation of horse hooves in China dates to the Warring States period (476–221 BC), during which Zhuangzi recommended shaving horse hooves to keep them in good shape. The Discourses on Salt and Iron in 81 BC mentions using leather shoes, but it is not clear if they were used for protecting horse hooves or to aid in mounting the horse. Remnants of iron horseshoes have been found in what is now northeast China, but the tombs date to the Goguryeo period in 414 AD. A mural in the Mogao Caves dated to 584 AD depicts a man caring for a horse's hoof, which some speculate might be depicting horseshoe nailing, but the mural is too eroded to tell clearly.

The earliest reference to iron horseshoes in China dates to 938 AD during the Five Dynasties and Ten Kingdoms period. A monk named Gao Juhui sent to the Western Regions writes that the people in Ganzhou (now Zhangye) taught him how to make "horse hoof muse", which had four holes in it that connected to four holes in the horse's hoof, and were thus put together. They also recommended using yak skin shoes for camel hooves. Iron horseshoes however did not become common for another three centuries. Zhao Rukuo writes in Zhu Fan Zhi, finished in 1225, that the horses of the Arabs and Persians used metal for horse shoes, implying that horses in China did not. After the establishment of the Yuan dynasty in 1271 AD, iron horseshoes became more common in northern China. When Thomas Blakiston travelled up the Yangtze, he noted that in Sichuan "cattle wore straw shoes to prevent their slipping on the wet ground" while in northern China, "horses and cattle are shod with iron shoes and nails." The majority of Chinese horseshoe discoveries have been in Jilin, Heilongjiang, Liaoning, Sichuan, and Tibet.

Environmental changes linked to domestication
Many changes brought about by the domestication of the horse have led to a need for shoes for numerous reasons, mostly linked to management that results in horses' hooves hardening less and being more vulnerable to injury. In the wild, a horse may travel up to 50 mi per day to obtain adequate forage. While horses in the wild cover large areas of terrain, they usually do so at relatively slow speeds, unless being chased by a predator. They also tend to live in arid steppe climates. The consequence of slow but nonstop travel in a dry climate is that horses' feet are naturally worn to a small, smooth, even, and hard state. The continual stimulation of the sole of the foot keeps it thick and hard. However, in domestication, the manner in which horses are used differs from what they would encounter in their natural environment. Domesticated horses are brought to colder and wetter areas than their ancestral habitat. These softer and heavier soils soften the hooves and make them prone to splitting, thus making hoof protection necessary.

Physical stresses requiring horseshoes

 * Abnormal stress: Horses' hooves can become quite worn out when subjected to the added weight and stress of a rider, pack load, cart, or wagon.

 * Corrective shoeing: The shape, weight, and thickness of a horseshoe can significantly affect the horse's gait. Farriers may forge custom shoes to help horses with bone or muscle problems in their legs, or fit commercially available remedial shoes.
 * Traction: Traction devices such as borium for ice, horse shoe studs for muddy or slick conditions, calks, carbide-tipped road nails and rims are useful for performance horses such as eventers, show jumpers, polo ponies, and other horses that perform at high speeds, over changing terrain, or in less-than-ideal footing.
 * Gait manipulation: Some breeds such as the Saddlebred, Tennessee Walking Horse, and other gaited horses are judged on their high-stepping movement. Special shoeing can help enhance their natural movement.
 * Racing horses with weakness in their foot or leg require specialized horseshoes.

Horseshoeing theories and debates
Domestic horses do not always require shoes. When possible, a "barefoot" hoof, at least for part of every year, is a healthy option for most horses. However, horseshoes have their place and can help prevent excess or abnormal hoof wear and injury to the foot. Many horses go without shoes year round, some using temporary protection such as hoof boots for short-term use.

Process of shoeing
Shoeing, when performed correctly, causes no pain to the animal. Farriers trim the insensitive part of the hoof, which is the same area into which they drive the nails. This is analogous to a manicure on a human fingernail, only on a much larger scale.

Before beginning to shoe, the farrier removes the old shoe using pincers (shoe pullers) and trims the hoof wall to the desired length with nippers, a sharp pliers-like tool, and the sole and frog of the hoof with a hoof knife. Shoes do not allow the hoof to wear down as it naturally would in the wild, and it can then become too long. The coffin bone inside the hoof should line up straight with both bones in the pastern. If the excess hoof is not trimmed, the bones will become misaligned, which would place stress on the legs of the animal.

Shoes are then measured to the foot and bent to the correct shape using a hammer, anvil, forge, and other modifications, such as taps for shoe studs, are added. Farriers may either cold shoe, in which they bend the metal shoe without heating it, or hot shoe, in which they place the metal in a forge before bending it. Hot shoeing can be more time consuming, and requires the farrier to have access to a forge; however, it usually provides a better fit, as the mark made on the hoof from the hot shoe can show how even it lies. It also allows the farrier to make more modifications to the shoe, such as drawing toe- and quarter-clips. The farrier must take care not to hold the hot shoe against the hoof too long, as the heat can damage the hoof.

Hot shoes are placed in water to cool them. The farrier then nails the shoes on by driving the nails into the hoof wall at the white line of the hoof. The nails are shaped in such a way that they bend outward as they are driven in, avoiding the sensitive inner part of the foot, so they emerge on the sides of the hoof. When the nail has been completely driven, the farrier cuts off the sharp points and uses a clincher (a form of tongs made especially for this purpose) or a clinching block with hammer to bend the rest of the nail so it is almost flush with the hoof wall. This prevents the nail from getting caught on anything, and also helps to hold the nail, and therefore the shoe, in place.

The farrier then uses a rasp (large file), to smooth the edge where it meets the shoe and eliminate any sharp edges left from cutting off the nails.

Superstition
Horseshoes have long been considered lucky. They were originally made of iron, a material that was believed to ward off evil spirits, and traditionally were held in place with seven nails, seven being the luckiest number. The superstition acquired a further Christian twist due to a legend surrounding the tenth-century saint Dunstan, who worked as a blacksmith before becoming Archbishop of Canterbury. The legend recounts that, one day, the Devil walked into Dunstan's shop and asked him to shoe his horse. Dunstan pretended not to recognize him, and agreed to the request; but rather than nailing the shoe to the horse's hoof, he nailed it to the Devil's own foot, causing him great pain. Dunstan eventually agreed to remove the shoe, but only after extracting a promise that the Devil would never enter a household with a horseshoe nailed to the door.

Opinion is divided as to which way up the horseshoe ought to be nailed. Some say the ends should point up, so that the horseshoe catches the luck, and that a horseshoe with ends pointing down allows the good luck to be lost; others say the ends should point down, so that the luck is poured upon those entering the home. Superstitious sailors believe that nailing a horseshoe to the mast will help their vessel avoid storms.

Heraldry
In heraldry, horseshoes most often occur as canting charges, such as in the arms of families with names like Farrier, Marshall, and Smith. A horseshoe (together with two hammers) also appears in the arms of Hammersmith and Fulham, a borough in London.

The flag of Rutland, England's smallest historic county, consists of a golden horseshoe laid over a field scattered with acorns. This refers to an ancient tradition in which every noble visiting Oakham, Rutland's county town, presents a horseshoe to the Lord of the Manor, which is then nailed to the wall of Oakham Castle. Over the centuries, the Castle has amassed a vast collection of horseshoes, the oldest of which date from the 15th century.

Monuments and structures
A massive golden horseshoe structure is erected over the shopping mall of the Tuuri village in Alavus, a town of Finland. It is one of the most famous monuments in the locality; however, it stands at number three in Reuters' list of world's ugliest buildings and monuments.

Sport
The sport of horseshoes involves a horseshoe being thrown as close as possible to a rod in order to score points. As far as it is known, the sport is as old as horseshoes themselves. While traditional horseshoes can still be used, most organized versions of the game use specialized sport horseshoes, which do not fit on horses' hooves.

title: Horseshoe