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Occam's razor

In philosophy, Occam's razor (also spelled Ockham's razor or Ocham's razor; novacula Occami) is the problem-solving principle that recommends searching for explanations constructed with the smallest possible set of elements. It is also known as the principle of parsimony or the law of parsimony (lex parsimoniae). Attributed to William of Ockham, a 14th-century English philosopher and theologian, it is frequently cited as Entia non sunt multiplicanda praeter necessitatem, which translates as "Entities must not be multiplied beyond necessity", although Occam never used these exact words. Popularly, the principle is sometimes paraphrased as "The simplest explanation is usually the best one."

This philosophical razor advocates that when presented with competing hypotheses about the same prediction and both theories have equal explanatory power one should prefer the hypothesis that requires the fewest assumptions and that this is not meant to be a way of choosing between hypotheses that make different predictions. Similarly, in science, Occam's razor is used as an abductive heuristic in the development of theoretical models rather than as a rigorous arbiter between candidate models.

History
The phrase Occam's razor did not appear until a few centuries after William of Ockham's death in 1347. Libert Froidmont, in his On Christian Philosophy of the Soul, gives him credit for the phrase, speaking of "novacula occami". Ockham did not invent this principle, but its fame—and its association with him—may be due to the frequency and effectiveness with which he used it. Ockham stated the principle in various ways, but the most popular version, "Entities are not to be multiplied without necessity" (Non sunt multiplicanda entia sine necessitate) was formulated by the Irish Franciscan philosopher John Punch in his 1639 commentary on the works of Duns Scotus.

Formulations before William of Ockham

The origins of what has come to be known as Occam's razor are traceable to the works of earlier philosophers such as John Duns Scotus (1265–1308), Robert Grosseteste (1175–1253), Maimonides (Moses ben-Maimon, 1138–1204), and even Aristotle (384–322 BC). Aristotle writes in his Posterior Analytics, "We may assume the superiority ceteris paribus [other things being equal] of the demonstration which derives from fewer postulates or hypotheses." Ptolemy (c. AD 90) stated, "We consider it a good principle to explain the phenomena by the simplest hypothesis possible."

Phrases such as "It is vain to do with more what can be done with fewer" and "A plurality is not to be posited without necessity" were commonplace in 13th-century scholastic writing. Robert Grosseteste, in Commentary on [Aristotle's] the Posterior Analytics Books (Commentarius in Posteriorum Analyticorum Libros) (c. 1217–1220), declares: "That is better and more valuable which requires fewer, other circumstances being equal... For if one thing were demonstrated from many and another thing from fewer equally known premises, clearly that is better which is from fewer because it makes us know quickly, just as a universal demonstration is better than particular because it produces knowledge from fewer premises. Similarly in natural science, in moral science, and in metaphysics the best is that which needs no premises and the better that which needs the fewer, other circumstances being equal."

The Summa Theologica of Thomas Aquinas (1225–1274) states that "it is superfluous to suppose that what can be accounted for by a few principles has been produced by many." Aquinas uses this principle to construct an objection to God's existence, an objection that he in turn answers and refutes generally (cf. quinque viae), and specifically, through an argument based on causality. Hence, Aquinas acknowledges the principle that today is known as Occam's razor, but prefers causal explanations to other simple explanations (cf. also Correlation does not imply causation).

William of Ockham
William of Ockham (circa 1287–1347) was an English Franciscan friar and theologian, an influential medieval philosopher and a nominalist. His popular fame as a great logician rests chiefly on the maxim attributed to him and known as Occam's razor. The term razor refers to distinguishing between two hypotheses either by "shaving away" unnecessary assumptions or cutting apart two similar conclusions.

While it has been claimed that Occam's razor is not found in any of William's writings, one can cite statements such as Numquam ponenda est pluralitas sine necessitate ("Plurality must never be posited without necessity"), which occurs in his theological work on the Sentences of Peter Lombard (Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi; ed. Lugd., 1495, i, dist. 27, qu. 2, K).

Nevertheless, the precise words sometimes attributed to William of Ockham, Entia non sunt multiplicanda praeter necessitatem (Entities must not be multiplied beyond necessity), are absent in his extant works; this particular phrasing comes from John Punch, who described the principle as a "common axiom" (axioma vulgare) of the Scholastics. William of Ockham himself seems to restrict the operation of this principle in matters pertaining to miracles and God's power, considering a plurality of miracles possible in the Eucharist simply because it pleases God.

This principle is sometimes phrased as Pluralitas non est ponenda sine necessitate ("Plurality should not be posited without necessity"). In his Summa Totius Logicae, i. 12, William of Ockham cites the principle of economy, Frustra fit per plura quod potest fieri per pauciora ("It is futile to do with more things that which can be done with fewer"; Thorburn, 1918, pp. 352–53; Kneale and Kneale, 1962, p. 243.)

Later formulations
To quote Isaac Newton, "We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore, to the same natural effects we must, as far as possible, assign the same causes."

In the sentence hypotheses non fingo, Newton affirms the success of this approach.

Bertrand Russell offers a particular version of Occam's razor: "Whenever possible, substitute constructions out of known entities for inferences to unknown entities."

Around 1960, Ray Solomonoff founded the theory of universal inductive inference, the theory of prediction based on observations – for example, predicting the next symbol based upon a given series of symbols. The only assumption is that the environment follows some unknown but computable probability distribution. This theory is a mathematical formalization of Occam's razor.

Another technical approach to Occam's razor is ontological parsimony. Parsimony means spareness and is also referred to as the Rule of Simplicity. This is considered a strong version of Occam's razor. A variation used in medicine is called the "Zebra": a physician should reject an exotic medical diagnosis when a more commonplace explanation is more likely, derived from Theodore Woodward's dictum "When you hear hoofbeats, think of horses not zebras".

Ernst Mach formulated the stronger version of Occam's razor into physics, which he called the Principle of Economy stating: "Scientists must use the simplest means of arriving at their results and exclude everything not perceived by the senses."

This principle goes back at least as far as Aristotle, who wrote "Nature operates in the shortest way possible." The idea of parsimony or simplicity in deciding between theories, though not the intent of the original expression of Occam's razor, has been assimilated into common culture as the widespread layman's formulation that "the simplest explanation is usually the correct one."

Aesthetic
Prior to the 20th century, it was a commonly held belief that nature itself was simple and that simpler hypotheses about nature were thus more likely to be true. Thomas Aquinas made this argument in the 13th century, writing, "If a thing can be done adequately by means of one, it is superfluous to do it by means of several; for we observe that nature does not employ two instruments [if] one suffices."

Beginning in the 20th century, epistemological justifications based on induction, logic, pragmatism, and especially probability theory have become more popular among philosophers.

Empirical
Occam's razor has gained strong empirical support in helping to converge on better theories (see Uses section below for some examples).

In the related concept of overfitting, excessively complex models are affected by statistical noise (a problem also known as the bias–variance tradeoff), whereas simpler models may capture the underlying structure better and may thus have better predictive performance. It is, however, often difficult to deduce which part of the data is noise (cf. model selection, test set, minimum description length, Bayesian inference, etc.).

Testing the razor
The razor's statement that "other things being equal, simpler explanations are generally better than more complex ones" is amenable to empirical testing. Another interpretation of the razor's statement would be that "simpler hypotheses are generally better than the complex ones". The procedure to test the former interpretation would compare the track records of simple and comparatively complex explanations. If one accepts the first interpretation, the validity of Occam's razor as a tool would then have to be rejected if the more complex explanations were more often correct than the less complex ones (while the converse would lend support to its use). If the latter interpretation is accepted, the validity of Occam's razor as a tool could possibly be accepted if the simpler hypotheses led to correct conclusions more often than not.

Even if some increases in complexity are sometimes necessary, there still remains a justified general bias toward the simpler of two competing explanations. To understand why, consider that for each accepted explanation of a phenomenon, there is always an infinite number of possible, more complex, and ultimately incorrect, alternatives. This is so because one can always burden a failing explanation with an ad hoc hypothesis. Ad hoc hypotheses are justifications that prevent theories from being falsified.

For example, if a man, accused of breaking a vase, makes supernatural claims that leprechauns were responsible for the breakage, a simple explanation might be that the man did it, but ongoing ad hoc justifications (e.g., "... and that's not me breaking it on the film; they tampered with that, too") could successfully prevent complete disproof. This endless supply of elaborate competing explanations, called saving hypotheses, cannot be technically ruled out – except by using Occam's razor.

Any more complex theory might still possibly be true. A study of the predictive validity of Occam's razor found 32 published papers that included 97 comparisons of economic forecasts from simple and complex forecasting methods. None of the papers provided a balance of evidence that complexity of method improved forecast accuracy. In the 25 papers with quantitative comparisons, complexity increased forecast errors by an average of 27 percent.

Mathematical
One justification of Occam's razor is a direct result of basic probability theory. By definition, all assumptions introduce possibilities for error; if an assumption does not improve the accuracy of a theory, its only effect is to increase the probability that the overall theory is wrong.

There have also been other attempts to derive Occam's razor from probability theory, including notable attempts made by Harold Jeffreys and E. T. Jaynes. The probabilistic (Bayesian) basis for Occam's razor is elaborated by David J. C. MacKay in chapter 28 of his book Information Theory, Inference, and Learning Algorithms, where he emphasizes that a prior bias in favor of simpler models is not required.

William H. Jefferys and James O. Berger (1991) generalize and quantify the original formulation's "assumptions" concept as the degree to which a proposition is unnecessarily accommodating to possible observable data. They state, "A hypothesis with fewer adjustable parameters will automatically have an enhanced posterior probability, due to the fact that the predictions it makes are sharp." The use of "sharp" here is not only a tongue-in-cheek reference to the idea of a razor, but also indicates that such predictions are more accurate than competing predictions. The model they propose balances the precision of a theory's predictions against their sharpness, preferring theories that sharply make correct predictions over theories that accommodate a wide range of other possible results. This, again, reflects the mathematical relationship between key concepts in Bayesian inference (namely marginal probability, conditional probability, and posterior probability).

The bias–variance tradeoff is a framework that incorporates the Occam's razor principle in its balance between overfitting (associated with lower bias but higher variance) and underfitting (associated with lower variance but higher bias).

Karl Popper
Karl Popper argues that a preference for simple theories need not appeal to practical or aesthetic considerations. Our preference for simplicity may be justified by its falsifiability criterion: we prefer simpler theories to more complex ones "because their empirical content is greater; and because they are better testable". The idea here is that a simple theory applies to more cases than a more complex one, and is thus more easily falsifiable. This is again comparing a simple theory to a more complex theory where both explain the data equally well.

Elliott Sober
The philosopher of science Elliott Sober once argued along the same lines as Popper, tying simplicity with "informativeness": The simplest theory is the more informative, in the sense that it requires less information to a question. He has since rejected this account of simplicity, purportedly because it fails to provide an epistemic justification for simplicity. He now believes that simplicity considerations (and considerations of parsimony in particular) do not count unless they reflect something more fundamental. Philosophers, he suggests, may have made the error of hypostatizing simplicity (i.e., endowed it with a sui generis existence), when it has meaning only when embedded in a specific context (Sober 1992). If we fail to justify simplicity considerations on the basis of the context in which we use them, we may have no non-circular justification: "Just as the question 'why be rational?' may have no non-circular answer, the same may be true of the question 'why should simplicity be considered in evaluating the plausibility of hypotheses?

Richard Swinburne
Richard Swinburne argues for simplicity on logical grounds:

"... the simplest hypothesis proposed as an explanation of phenomena is more likely to be the true one than is any other available hypothesis, that its predictions are more likely to be true than those of any other available hypothesis, and that it is an ultimate a priori epistemic principle that simplicity is evidence for truth."

According to Swinburne, since our choice of theory cannot be determined by data (see Underdetermination and Duhem–Quine thesis), we must rely on some criterion to determine which theory to use. Since it is absurd to have no logical method for settling on one hypothesis amongst an infinite number of equally data-compliant hypotheses, we should choose the simplest theory: "Either science is irrational [in the way it judges theories and predictions probable] or the principle of simplicity is a fundamental synthetic a priori truth."

Ludwig Wittgenstein
From the Tractatus Logico-Philosophicus:

 * 3.328 "If a sign is not necessary then it is meaningless. That is the meaning of Occam's Razor."
 * (If everything in the symbolism works as though a sign had meaning, then it has meaning.)

and on the related concept of "simplicity":
 * 4.04 "In the proposition, there must be exactly as many things distinguishable as there are in the state of affairs, which it represents. They must both possess the same logical (mathematical) multiplicity (cf. Hertz's Mechanics, on Dynamic Models)."
 * 5.47321 "Occam's Razor is, of course, not an arbitrary rule nor one justified by its practical success. It simply says that unnecessary elements in a symbolism mean nothing. Signs which serve one purpose are logically equivalent; signs which serve no purpose are logically meaningless."

 * 6.363 "The procedure of induction consists in accepting as true the simplest law that can be reconciled with our experiences."

Science and the scientific method
In science, Occam's razor is used as a heuristic to guide scientists in developing theoretical models rather than as an arbiter between published models. In physics, parsimony was an important heuristic in Albert Einstein's formulation of special relativity, in the development and application of the principle of least action by Pierre Louis Maupertuis and Leonhard Euler, and in the development of quantum mechanics by Max Planck, Werner Heisenberg and Louis de Broglie.

In chemistry, Occam's razor is often an important heuristic when developing a model of a reaction mechanism. Although it is useful as a heuristic in developing models of reaction mechanisms, it has been shown to fail as a criterion for selecting among some selected published models. In this context, Einstein himself expressed caution when he formulated Einstein's Constraint: "It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience." An often-quoted version of this constraint (which cannot be verified as posited by Einstein himself) reduces this to "Everything should be kept as simple as possible, but not simpler."

In the scientific method, Occam's razor is not considered an irrefutable principle of logic or a scientific result; the preference for simplicity in the scientific method is based on the falsifiability criterion. For each accepted explanation of a phenomenon, there may be an extremely large, perhaps even incomprehensible, number of possible and more complex alternatives. Since failing explanations can always be burdened with ad hoc hypotheses to prevent them from being falsified, simpler theories are preferable to more complex ones because they tend to be more testable. As a logical principle, Occam's razor would demand that scientists accept the simplest possible theoretical explanation for existing data. However, science has shown repeatedly that future data often support more complex theories than do existing data. Science prefers the simplest explanation that is consistent with the data available at a given time, but the simplest explanation may be ruled out as new data become available. That is, science is open to the possibility that future experiments might support more complex theories than demanded by current data and is more interested in designing experiments to discriminate between competing theories than favoring one theory over another based merely on philosophical principles.

When scientists use the idea of parsimony, it has meaning only in a very specific context of inquiry. Several background assumptions are required for parsimony to connect with plausibility in a particular research problem. The reasonableness of parsimony in one research context may have nothing to do with its reasonableness in another. It is a mistake to think that there is a single global principle that spans diverse subject matter.

It has been suggested that Occam's razor is a widely accepted example of extraevidential consideration, even though it is entirely a metaphysical assumption. Most of the time, however, Occam's razor is a conservative tool, cutting out "crazy, complicated constructions" and assuring "that hypotheses are grounded in the science of the day", thus yielding "normal" science: models of explanation and prediction. There are, however, notable exceptions where Occam's razor turns a conservative scientist into a reluctant revolutionary. For example, Max Planck interpolated between the Wien and Jeans radiation laws and used Occam's razor logic to formulate the quantum hypothesis, even resisting that hypothesis as it became more obvious that it was correct.

Appeals to simplicity were used to argue against the phenomena of meteorites, ball lightning, continental drift, and reverse transcriptase. One can argue for atomic building blocks for matter, because it provides a simpler explanation for the observed reversibility of both and chemical reactions as simple separation and rearrangements of atomic building blocks. At the time, however, the atomic theory was considered more complex because it implied the existence of invisible particles that had not been directly detected. Ernst Mach and the logical positivists rejected John Dalton's atomic theory until the reality of atoms was more evident in Brownian motion, as shown by Albert Einstein.

In the same way, postulating the aether is more complex than transmission of light through a vacuum. At the time, however, all known waves propagated through a physical medium, and it seemed simpler to postulate the existence of a medium than to theorize about wave propagation without a medium. Likewise, Isaac Newton's idea of light particles seemed simpler than Christiaan Huygens's idea of waves, so many favored it. In this case, as it turned out, neither the wave—nor the particle—explanation alone suffices, as light behaves like waves and like particles.

Three axioms presupposed by the scientific method are realism (the existence of objective reality), the existence of natural laws, and the constancy of natural law. Rather than depend on provability of these axioms, science depends on the fact that they have not been objectively falsified. Occam's razor and parsimony support, but do not prove, these axioms of science. The general principle of science is that theories (or models) of natural law must be consistent with repeatable experimental observations. This ultimate arbiter (selection criterion) rests upon the axioms mentioned above.

If multiple models of natural law make exactly the same testable predictions, they are equivalent and there is no need for parsimony to choose a preferred one. For example, Newtonian, Hamiltonian and Lagrangian classical mechanics are equivalent. Physicists have no interest in using Occam's razor to say the other two are wrong. Likewise, there is no demand for simplicity principles to arbitrate between wave and matrix formulations of quantum mechanics. Science often does not demand arbitration or selection criteria between models that make the same testable predictions.

Biology
Biologists or philosophers of biology use Occam's razor in either of two contexts both in evolutionary biology: the units of selection controversy and systematics. George C. Williams in his book Adaptation and Natural Selection (1966) argues that the best way to explain altruism among animals is based on low-level (i.e., individual) selection as opposed to high-level group selection. Altruism is defined by some evolutionary biologists (e.g., R. Alexander, 1987; W. D. Hamilton, 1964) as behavior that is beneficial to others (or to the group) at a cost to the individual, and many posit individual selection as the mechanism that explains altruism solely in terms of the behaviors of individual organisms acting in their own self-interest (or in the interest of their genes, via kin selection). Williams was arguing against the perspective of others who propose selection at the level of the group as an evolutionary mechanism that selects for altruistic traits (e.g., D. S. Wilson & E. O. Wilson, 2007). The basis for Williams' contention is that of the two, individual selection is the more parsimonious theory. In doing so he is invoking a variant of Occam's razor known as Morgan's Canon: "In no case is an animal activity to be interpreted in terms of higher psychological processes, if it can be fairly interpreted in terms of processes which stand lower in the scale of psychological evolution and development." (Morgan 1903).

However, more recent biological analyses, such as Richard Dawkins' The Selfish Gene, have contended that Morgan's Canon is not the simplest and most basic explanation. Dawkins argues the way evolution works is that the genes propagated in most copies end up determining the development of that particular species, i.e., natural selection turns out to select specific genes, and this is really the fundamental underlying principle that automatically gives individual and group selection as emergent features of evolution.

Zoology provides an example. Muskoxen, when threatened by wolves, form a circle with the males on the outside and the females and young on the inside. This is an example of a behavior by the males that seems to be altruistic. The behavior is disadvantageous to them individually but beneficial to the group as a whole and was thus seen by some to support the group selection theory. Another interpretation is kin selection: if the males are protecting their offspring, they are protecting copies of their own alleles. Engaging in this behavior would be favored by individual selection if the cost to the male musk ox is less than half of the benefit received by his calf – which could easily be the case if wolves have an easier time killing calves than adult males. It could also be the case that male musk oxen would be individually less likely to be killed by wolves if they stood in a circle with their horns pointing out, regardless of whether they were protecting the females and offspring. That would be an example of regular natural selection – a phenomenon called "the selfish herd".

Systematics is the branch of biology that attempts to establish patterns of relationship among biological taxa, today generally thought to reflect evolutionary history. It is also concerned with their classification. There are three primary camps in systematics: cladists, pheneticists, and evolutionary taxonomists. Cladists hold that classification should be based on synapomorphies (shared, derived character states), pheneticists contend that overall similarity (synapomorphies and complementary symplesiomorphies) is the determining criterion, while evolutionary taxonomists say that both genealogy and similarity count in classification (in a manner determined by the evolutionary taxonomist).

It is among the cladists that Occam's razor is applied, through the method of cladistic parsimony. Cladistic parsimony (or maximum parsimony) is a method of phylogenetic inference that yields phylogenetic trees (more specifically, cladograms). Cladograms are branching, diagrams used to represent hypotheses of relative degree of relationship, based on synapomorphies. Cladistic parsimony is used to select as the preferred hypothesis of relationships the cladogram that requires the fewest implied character state transformations (or smallest weight, if characters are differentially weighted). Critics of the cladistic approach often observe that for some types of data, parsimony could produce the wrong results, regardless of how much data is collected (this is called statistical inconsistency, or long branch attraction). However, this criticism is also potentially true for any type of phylogenetic inference, unless the model used to estimate the tree reflects the way that evolution actually happened. Because this information is not empirically accessible, the criticism of statistical inconsistency against parsimony holds no force. For a book-length treatment of cladistic parsimony, see Elliott Sober's Reconstructing the Past: Parsimony, Evolution, and Inference (1988). For a discussion of both uses of Occam's razor in biology, see Sober's article "Let's Razor Ockham's Razor" (1990).

Other methods for inferring evolutionary relationships use parsimony in a more general way. Likelihood methods for phylogeny use parsimony as they do for all likelihood tests, with hypotheses requiring fewer differing parameters (i.e., numbers or different rates of character change or different frequencies of character state transitions) being treated as null hypotheses relative to hypotheses requiring more differing parameters. Thus, complex hypotheses must predict data much better than do simple hypotheses before researchers reject the simple hypotheses. Recent advances employ information theory, a close cousin of likelihood, which uses Occam's razor in the same way. The choice of the "shortest tree" relative to a not-so-short tree under any optimality criterion (smallest distance, fewest steps, or maximum likelihood) is always based on parsimony.

Francis Crick has commented on potential limitations of Occam's razor in biology. He advances the argument that because biological systems are the products of (an ongoing) natural selection, the mechanisms are not necessarily optimal in an obvious sense. He cautions: "While Ockham's razor is a useful tool in the physical sciences, it can be a very dangerous implement in biology. It is thus very rash to use simplicity and elegance as a guide in biological research." This is an ontological critique of parsimony.

In biogeography, parsimony is used to infer ancient vicariant events or migrations of species or populations by observing the geographic distribution and relationships of existing organisms. Given the phylogenetic tree, ancestral population subdivisions are inferred to be those that require the minimum amount of change.

Religion
In the philosophy of religion, Occam's razor is sometimes applied to the existence of God. William of Ockham himself was a Christian. He believed in God, and in the authority of Christian scripture; he writes that "nothing ought to be posited without a reason given, unless it is self-evident (literally, known through itself) or known by experience or proved by the authority of Sacred Scripture." Ockham believed that an explanation has no sufficient basis in reality when it does not harmonize with reason, experience, or the Bible. Unlike many theologians of his time, though, Ockham did not believe God could be logically proven with arguments. To Ockham, science was a matter of discovery; theology was a matter of revelation and faith. He states: "Only faith gives us access to theological truths. The ways of God are not open to reason, for God has freely chosen to create a world and establish a way of salvation within it apart from any necessary laws that human logic or rationality can uncover."

Thomas Aquinas, in the Summa Theologica, uses a formulation of Occam's razor to construct an objection to the idea that God exists, which he refutes directly with a counterargument:

"Further, it is superfluous to suppose that what can be accounted for by a few principles has been produced by many. But it seems that everything we see in the world can be accounted for by other principles, supposing God did not exist. For all natural things can be reduced to one principle which is nature; and all voluntary things can be reduced to one principle which is human reason, or will. Therefore there is no need to suppose God's existence."

In turn, Aquinas answers this with the quinque viae, and addresses the particular objection above with the following answer:

"Since nature works for a determinate end under the direction of a higher agent, whatever is done by nature must needs be traced back to God, as to its first cause. So also whatever is done voluntarily must also be traced back to some higher cause other than human reason or will, since these can change or fail; for all things that are changeable and capable of defect must be traced back to an immovable and self-necessary first principle, as was shown in the body of the Article."

Rather than argue for the necessity of a god, some theists base their belief upon grounds independent of, or prior to, reason, making Occam's razor irrelevant. This was the stance of Søren Kierkegaard, who viewed belief in God as a leap of faith that sometimes directly opposed reason. This is also the doctrine of Gordon Clark's presuppositional apologetics, with the exception that Clark never thought the leap of faith was contrary to reason (see also Fideism).

Various arguments in favor of God establish God as a useful or even necessary assumption. Contrastingly some anti-theists hold firmly to the belief that assuming the existence of God introduces unnecessary complexity (e.g., the Ultimate Boeing 747 gambit from Dawkins's The God Delusion ).

Another application of the principle is to be found in the work of George Berkeley (1685–1753). Berkeley was an idealist who believed that all of reality could be explained in terms of the mind alone. He invoked Occam's razor against materialism, stating that matter was not required by his metaphysics and was thus eliminable. One potential problem with this belief is that it's possible, given Berkeley's position, to find solipsism itself more in line with the razor than a God-mediated world beyond a single thinker.

Occam's razor may also be recognized in the apocryphal story about an exchange between Pierre-Simon Laplace and Napoleon. It is said that in praising Laplace for one of his recent publications, the emperor asked how it was that the name of God, which featured so frequently in the writings of Lagrange, appeared nowhere in Laplace's. At that, he is said to have replied, "It's because I had no need of that hypothesis." Though some points of this story illustrate Laplace's atheism, more careful consideration suggests that he may instead have intended merely to illustrate the power of methodological naturalism, or even simply that the fewer logical premises one assumes, the stronger is one's conclusion.

Philosophy of mind
In his article "Sensations and Brain Processes" (1959), J. J. C. Smart invoked Occam's razor with the aim to justify his preference of the mind-brain identity theory over spirit-body dualism. Dualists state that there are two kinds of substances in the universe: physical (including the body) and spiritual, which is non-physical. In contrast, identity theorists state that everything is physical, including consciousness, and that there is nothing nonphysical. Though it is impossible to appreciate the spiritual when limiting oneself to the physical, Smart maintained that identity theory explains all phenomena by assuming only a physical reality. Subsequently, Smart has been severely criticized for his use (or misuse) of Occam's razor and ultimately retracted his advocacy of it in this context. Paul Churchland (1984) states that by itself Occam's razor is inconclusive regarding duality. In a similar way, Dale Jacquette (1994) stated that Occam's razor has been used in attempts to justify eliminativism and reductionism in the philosophy of mind. Eliminativism is the thesis that the ontology of folk psychology including such entities as "pain", "joy", "desire", "fear", etc., are eliminable in favor of an ontology of a completed neuroscience.

Penal ethics
In penal theory and the philosophy of punishment, parsimony refers specifically to taking care in the distribution of punishment in order to avoid excessive punishment. In the utilitarian approach to the philosophy of punishment, Jeremy Bentham's "parsimony principle" states that any punishment greater than is required to achieve its end is unjust. The concept is related but not identical to the legal concept of proportionality. Parsimony is a key consideration of the modern restorative justice, and is a component of utilitarian approaches to punishment, as well as the prison abolition movement. Bentham believed that true parsimony would require punishment to be individualised to take account of the sensibility of the individual—an individual more sensitive to punishment should be given a proportionately lesser one, since otherwise needless pain would be inflicted. Later utilitarian writers have tended to abandon this idea, in large part due to the impracticality of determining each alleged criminal's relative sensitivity to specific punishments.

Probability theory and statistics
Marcus Hutter's universal artificial intelligence builds upon Solomonoff's mathematical formalization of the razor to calculate the expected value of an action.

There are various papers in scholarly journals deriving formal versions of Occam's razor from probability theory, applying it in statistical inference, and using it to come up with criteria for penalizing complexity in statistical inference. Papers have suggested a connection between Occam's razor and Kolmogorov complexity.

One of the problems with the original formulation of the razor is that it only applies to models with the same explanatory power (i.e., it only tells us to prefer the simplest of equally good models). A more general form of the razor can be derived from Bayesian model comparison, which is based on Bayes factors and can be used to compare models that do not fit the observations equally well. These methods can sometimes optimally balance the complexity and power of a model. Generally, the exact Occam factor is intractable, but approximations such as Akaike information criterion, Bayesian information criterion, Variational Bayesian methods, false discovery rate, and Laplace's method are used. Many artificial intelligence researchers are now employing such techniques, for instance through work on Occam Learning or more generally on the Free energy principle.

Statistical versions of Occam's razor have a more rigorous formulation than what philosophical discussions produce. In particular, they must have a specific definition of the term simplicity, and that definition can vary. For example, in the Kolmogorov–Chaitin minimum description length approach, the subject must pick a Turing machine whose operations describe the basic operations believed to represent "simplicity" by the subject. However, one could always choose a Turing machine with a simple operation that happened to construct one's entire theory and would hence score highly under the razor. This has led to two opposing camps: one that believes Occam's razor is objective, and one that believes it is subjective.

Objective razor
The minimum instruction set of a universal Turing machine requires approximately the same length description across different formulations, and is small compared to the Kolmogorov complexity of most practical theories. Marcus Hutter has used this consistency to define a "natural" Turing machine of small size as the proper basis for excluding arbitrarily complex instruction sets in the formulation of razors. Describing the program for the universal program as the "hypothesis", and the representation of the evidence as program data, it has been formally proven under Zermelo–Fraenkel set theory that "the sum of the log universal probability of the model plus the log of the probability of the data given the model should be minimized." Interpreting this as minimising the total length of a two-part message encoding model followed by data given model gives us the minimum message length (MML) principle.

One possible conclusion from mixing the concepts of Kolmogorov complexity and Occam's razor is that an ideal data compressor would also be a scientific explanation/formulation generator. Some attempts have been made to re-derive known laws from considerations of simplicity or compressibility.

According to Jürgen Schmidhuber, the appropriate mathematical theory of Occam's razor already exists, namely, Solomonoff's theory of optimal inductive inference and its extensions. See discussions in David L. Dowe's "Foreword re C. S. Wallace" for the subtle distinctions between the algorithmic probability work of Solomonoff and the MML work of Chris Wallace, and see Dowe's "MML, hybrid Bayesian network graphical models, statistical consistency, invariance and uniqueness" both for such discussions and for (in section 4) discussions of MML and Occam's razor. For a specific example of MML as Occam's razor in the problem of decision tree induction, see Dowe and Needham's "Message Length as an Effective Ockham's Razor in Decision Tree Induction".

Mathematical arguments against Occam's razor
The no free lunch (NFL) theorems for inductive inference prove that Occam's razor must rely on ultimately arbitrary assumptions concerning the prior probability distribution found in our world. Specifically, suppose one is given two inductive inference algorithms, A and B, where A is a Bayesian procedure based on the choice of some prior distribution motivated by Occam's razor (e.g., the prior might favor hypotheses with smaller Kolmogorov complexity). Suppose that B is the anti-Bayes procedure, which calculates what the Bayesian algorithm. A based on Occam's razor will predict – and then predicts the exact opposite. Then there are just as many actual priors (including those different from the Occam's razor prior assumed by A) in which algorithm B outperforms A as priors in which the procedure A based on Occam's razor comes out on top. In particular, the NFL theorems show that the "Occam factors" Bayesian argument for Occam's razor must make ultimately arbitrary modeling assumptions.

Software development
In software development, the rule of least power argues the correct programming language to use is the one that is simplest while also solving the targeted software problem. In that form the rule is often credited to Tim Berners-Lee since it appeared in his design guidelines for the original Hypertext Transfer Protocol. Complexity in this context is measured either by placing a language into the Chomsky hierarchy or by listing idiomatic features of the language and comparing according to some agreed to scale of difficulties between idioms. Many languages once thought to be of lower complexity have evolved or later been discovered to be more complex than originally intended; so, in practice this rule is applied to the relative ease of a programmer to obtain the power of the language, rather than the precise theoretical limits of the language.

Controversial aspects
Occam's razor is not an embargo against the positing of any kind of entity, or a recommendation of the simplest theory come what may. Occam's razor is used to adjudicate between theories that have already passed "theoretical scrutiny" tests and are equally well-supported by evidence. Furthermore, it may be used to prioritize empirical testing between two equally plausible but unequally testable hypotheses; thereby minimizing costs and wastes while increasing chances of falsification of the simpler-to-test hypothesis.

Another contentious aspect of the razor is that a theory can become more complex in terms of its structure (or syntax), while its ontology (or semantics) becomes simpler, or vice versa. Quine, in a discussion on definition, referred to these two perspectives as "economy of practical expression" and "economy in grammar and vocabulary", respectively.

Galileo Galilei lampooned the misuse of Occam's razor in his Dialogue. The principle is represented in the dialogue by Simplicio. The telling point that Galileo presented ironically was that if one really wanted to start from a small number of entities, one could always consider the letters of the alphabet as the fundamental entities, since one could construct the whole of human knowledge out of them.

Instances of using Occam's razor to justify belief in less complex and more simple theories have been criticized as using the razor inappropriately. For instance Francis Crick stated that "While Occam's razor is a useful tool in the physical sciences, it can be a very dangerous implement in biology. It is thus very rash to use simplicity and elegance as a guide in biological research."

Anti-razors
Occam's razor has met some opposition from people who consider it too extreme or rash. Walter Chatton (c. 1290–1343) was a contemporary of William of Ockham who took exception to Occam's razor and Ockham's use of it. In response he devised his own anti-razor: "If three things are not enough to verify an affirmative proposition about things, a fourth must be added and so on." Although there have been several philosophers who have formulated similar anti-razors since Chatton's time, no one anti-razor has perpetuated as notably as Chatton's anti-razor, although this could be the case of the Late Renaissance Italian motto of unknown attribution Se non è vero, è ben trovato ("Even if it is not true, it is well conceived") when referred to a particularly artful explanation.

Anti-razors have also been created by Gottfried Wilhelm Leibniz (1646–1716), Immanuel Kant (1724–1804), and Karl Menger (1902–1985). Leibniz's version took the form of a principle of plenitude, as Arthur Lovejoy has called it: the idea being that God created the most varied and populous of possible worlds. Kant felt a need to moderate the effects of Occam's razor and thus created his own counter-razor: "The variety of beings should not rashly be diminished."

Karl Menger found mathematicians to be too parsimonious with regard to variables so he formulated his Law Against Miserliness, which took one of two forms: "Entities must not be reduced to the point of inadequacy" and "It is vain to do with fewer what requires more." A less serious but even more extremist anti-razor is 'Pataphysics, the "science of imaginary solutions" developed by Alfred Jarry (1873–1907). Perhaps the ultimate in anti-reductionism, "'Pataphysics seeks no less than to view each event in the universe as completely unique, subject to no laws but its own." Variations on this theme were subsequently explored by the Argentine writer Jorge Luis Borges in his story/mock-essay "Tlön, Uqbar, Orbis Tertius". Physicist R. V. Jones contrived Crabtree's Bludgeon, which states that "[n]o set of mutually inconsistent observations can exist for which some human intellect cannot conceive a coherent explanation, however complicated."

Recently, American physicist Igor Mazin argued that because high-profile physics journals prefer publications offering exotic and unusual interpretations, the Occam's razor principle is being replaced by an "Inverse Occam's razor", implying that the simplest possible explanation is usually rejected.

Other
Since 2012 The Skeptic magazine annually awards the Ockham Awards, or simply the Ockhams, named after Occam's razor, at QED. The Ockhams were introduced by editor-in-chief Deborah Hyde to "recognise the effort and time that have gone into the community’s favourite skeptical blogs, skeptical podcasts, skeptical campaigns and outstanding contributors to the skeptical cause." The trophies, designed by Neil Davies and Karl Derrick, carry the upper text "Ockham's" and the lower text "The Skeptic. Shaving away unnecessary assumptions since 1285." Between the texts, there is an image of a double-edged safety razorblade, and both lower corners feature an image of William of Ockham's face.

title: Occam's razor


text:
Talk:Paclitaxel

Nomenclature
I added the nomenclature section from the Paclitaxel total synthesis article because it seems more relevant here. Hansonrstolaf (talk) 12:32, 6 March 2009 (UTC)

Wiernik
Peter Wiernik, M.D. a medical oncologist then at the Albert Einstein Cancer Center devised a method for preventing most of the anaphylactoid reactions to the drug, and thereby saved the drug from extinction and allowed clinical development to continue. He also published the earliest human pharmacokinetic studies of the drug.
 * An anonymous user added the above paragraph but managed to insert it between a different statement and its reference source so it appeared incorrectly to be sourced. Given that, and lack of any detail on what the 'anaphylactoid reactions' are or when this 'saving the drug from extinction' occurred, I have parked this on the talk page until someone can provide properly referenced detail. Js229 11:26, 10 September 2007 (UTC)
 * Will look into it. Le Prof  Leprof 7272 (talk) 22:41, 30 May 2014 (UTC)

Wikipedia is great
I was happy to see this article in the Wikipedia and delighted to be able to add a bit more information about Taxol's discoverers. I work at RTI and know Drs. Wall and Wani. Glad to be able to get them some Wikipedian recognition. SteveSmith

Thanks for your contributions! Man, Wikipedia is awesome -- a little over an hour after my original submission, someone who knows the creators of Taxol adds some very useful information on it. User:maveric149

Other sources of paclitaxel
I have read that Taxol can be produced also from a shrub common in Eastern Canada called ground hemlock or eastern yew (Taxus canadensis). See Natural resources Canada and CBC news. Is the drug produced from shrubs cheaper/simpler/higher quality than the drug produced by fermentation? Brona 15:33, 6 Jul 2004 (UTC)

 * In Biotechnology: An Introduction 2ed (ISBN 9780495112051) on page 128, the last line of a table labeled Some Pharmaceutical Products Manufactured Using Recombinant DNA Technology reads: Taxol - Plan product used for treatment of ovarian cancer; produced by E. coli. However, this doesn't seem correct considering the other reading I have done. Can anybody confirm if paclitaxel has ever been produced by E. coli? 70.237.144.179 07:27, 4 June 2007 (UTC)

Problem with Zhao paper reference and production in Nodulisporium
In 1993 it was discovered that taxol was also produced in a newly described fungus living in the yew tree, see: Stierle, A., G. Strobel, et al. (1993). "Taxol and Taxane Production by Taxomyces-Andreanae, an Endophytic Fungus of Pacific Yew." Science 260(5105): 214-216. It has since been found in a number of other endophytic fungi, some from other yews, some not; search Web of Science for "taxol and fungi" and you'll get a bunch of hits. Unfortuately, searching for "taxol and Nodulisporium" turns up nothing, not even the article cited here, from "Nature and Science" which I submit is a junk journal for the following reasons: the name is an amalgam of the two biggest journals, it doesn't show up on Web of Science or the CA Digital Library database, and the translation is atrocious.

Finally, the assertion that taxol is produced commercially in cultures of Nodulisporium is not even supported by the citation. The paper deals with the regeneration of fungal protoplasts, a tool used in genetic engineering of fungi. The study concludes that this is difficult to do with Nodulisporium, and suggests ways to improve the process. Even if Nodulisporium does make taxol, that's a long way from it being a commercial production strain. From what I've been able to find taxol is commercially produced using plant cell culture from another species of yew, Taxus baccata. --DLuber1 17:37, 6 August 2007 (UTC) -DL

 * Update: I followed the link at the top to check out the Pharmacology workgroup and joined, but after mousing around it looks like a pretty moribund group, despite the good looking top page: e.g. Announcements, Peer Review, Proposals, Votes and Surveys, Help Requests, Tasks that need attention, Article Worklist and Collaboration of the Month all have little or no content. I'm new to all this so maybe I'm missing something. Anyway, I don't know the ettiquette for editing pages, I figured I'd post something at the workgroup but it looks like nobody's home, so I'll note here that I think this entry needs correction, and if the original author or anyone else doesn't object in a few weeks I'll remove the Zhao reference and incorporate my comments and references. -DL --DLuber1 18:27, 7 August 2007 (UTC)

 * No need to wait I think. The whole discussion of past, present, and possible synthesis routes needs work. Be bold and put in what you've found. But the paper does say the 'taxol-producing fungus' and there look like a couple of papers in the reference list that might support that so I would suggest it is better to leave in something like 'there are claims that a fungus can be used to produce taxol (ref) but there seems be little practical application reported in the scientific literature ' after the main discussion about PCF. I'd like to see some discussion of the history of PCF development while you're at it :) Js229 21:59, 7 August 2007 (UTC)

 * There's something genuinely interesting going on here... Looking at  (Gliocladium sp.),  and  and  (Taxomyces andreanae),  (Botryodiplodia theobromae),  (Aspergillus niger),  (Cladosporium cladosporioides),  (Metarhizium anisopliae and others),  (Aspergillus candidus),  ("Mucor rouxianus sp."),  (Chaetomella raphigera),  (Phomopsis),  (Pestalotiopsis pauciseta),  (Pestalotiopsis terminaliae),  and  and  and (Pestalotiopsis microspora),  (Aspergillus fumigates),  (Sporormia minima, Trichothecium sp., and an unidentified dimorphic fungus),  (Tubercularia sp.) The co-culture idea is apparently ongoing:, ,.

 * Now from all this it's clear that there's one huge variety of bark fungi that produce this very, very odd looking molecule. A strange explanation I saw was that the endophytes "mimic the host biochemical diversity" - while I suppose you can make an evolutionary-arms-race argument to say why this should be so, it still seems hard to swallow.  The fungi apparently require precursors: sodium benzoate, sodium acetate, biotin, pyridoxal, and L-phenylalanine to assemble the taxol.  It looks like about half of the biosynthetic pathway has been traced to yew genes  so I can't blame it all on nanobacteria or fairies... I just don't understand why this molecule is made by so many different organisms. Wnt (talk) 23:05, 28 March 2010 (UTC)

 * Thank you for this, Wnt! If you come across a good secondary reference, let us know. Le Prof  Leprof 7272 (talk) 23:32, 30 May 2014 (UTC)

St. Petersburg Times
St. Petersburg Times November 8, 2004:" The St. Petersburg Times recently asked two University of South Florida professors to read a few Wikipedia articles on topics in their expertise. Chemistry professor Bill Baker said he was surprised at the amount of technical knowledge posted on the site, but said he found several small errors. 'The cancer drug Taxol, for example, is not produced by microbial fermentation.'

'That bothers me,' Baker said of the errors. 'I think that even if 99 percent of your facts check out, it is a disservice to promulgate 1 percent inaccuracies.'"

Probably out of date but just posting just in case.

lots of issues | leave me a message 08:30, 24 May 2005 (UTC)

 * . Also, your signature is confusing! JFW | T@lk  12:51, 24 May 2005 (UTC)
 * It still says this, but is cited. Huh? occono (talk) 09:26, 28 August 2009 (UTC)

License and name
I have put the license on the past tense as per Bristol Myers Squibb and replaced many Taxols with paclitaxels. Please revert if I'm wrong. Rich Farmbrough 21:30, 8 October 2005 (UTC)

Structure
I'd say the structure of taxol isn't "extremely" complex... it certainly is complex, yes, but the adjective "extremely" would suit more a molecule like Maitotoxin.

 * I disagree. Maitotoxin is actually simpler than Taxol, since it has a quasirepetitive motif with only a small set of functional groups.  However, judgement calls like that don't belong in wikipedia. —The preceding unsigned comment was added by 137.131.130.118 (talk) 10:23, 8 February 2007 (UTC).

 * The "crystal structure" given as a figure (reference 4) is not, in the traditional sense, a crystal structure obtained through typical single-crystal x-ray diffraction methods. This is because paclitaxel doesn't form good single crystals for traditional methods of analysis. In fact, there is only one known crystal structure of paclitaxel [D.  Mastropaolo, A.  Camerman, Y.  Luo and G.D.  Brayer, Proc.  Natl.  Acad.  Sci.  USA, 1995, 92, 6920-6924. ] This contains two molecules per asymmetric unit and crystallizes in the P21 space group. This form shared characteristics of the "polar" form predicted for paclitaxel. Unfortunately, the crystal also contains the toxic solvent dioxane and, therefore, isn't useful for studies in vivo. Because paclitaxel's bioactivity is strongly linked with its conformation, structural studies are extremely important for this molecule. E heider 01:12, 8 August 2007 (UTC)

 * What is the perceived point, of the impact on utility, of an adventitious dioxane molecule co-crystallizing with paclitaxel in the study you report (i.e., the basis for saying "the crystal… isn't useful for studies in vivo)? This seems a fantastically important study, with broad, significant impact on therapeutic use of the molecule and its analogs—insofar it unequivocally confirms the structure and stereochemistry derived via synthesis and NMR spectroscopy. Non? Le Prof  Leprof 7272 (talk) 23:27, 30 May 2014 (UTC)

Updates
Mostly spelling, capitalization, paragraph structure, readability, etc. However, clarification of various Taxus species and uses, with new info on current production methods. Thanks! Dcwest 19:35, 19 February 2007 (UTC)

Pierre Potier
See this press release.
 * Pierre Potier’s team also invented a process to produce, in unlimited quantity, a substance previously discovered in the United States, called TAXOL®, and made of yew bark extract. Thanks to the discovery by the Gif-sur-Yvette researchers of a precursor of Taxol® in local yew leaves, it is no longer necessary to cut down yew trees in order to make the drug.

CNRS is a fairly serious institution, so I'm inclined to believe them. I'm told that the patents over the production of Taxol and Taxotere are their first two patents in terms of income. This should surely be mentioned in the "production" section. David.Monniaux 10:59, 12 July 2007 (UTC)

 * I will look to see how their contributions can be substantiated independently, and so appear here. Cheers.  Le Prof  Leprof 7272 (talk) 23:20, 30 May 2014 (UTC)

Cruious
Is this considered a chemo drug?

 * The term 'chemotherapy' actually refers to any type of drug-related therapy, irregardless of disease state. However, in recent years, it has become associated with cancer drug therapies by most laypeople. Dr. Cash 02:43, 29 September 2007 (UTC)

IUPAC
ACETYLOXY IS ETHANOILOXY ? —Preceding unsigned comment added by 89.77.15.69 (talk) 02:42, 15 September 2007 (UTC)

Taxol Drug Box issues.
Please visit the blog posting I made tonight

http://www.chemspider.com/blog/?p=168

I cannot put into this email since there are a lot of graphics to consult.

Here's the bottom line for Taxol on Wikipedia.

I can confirm at this point the CAS Number is correct in Wikipedia.

I can confirm the structure on Wikipedia IS Correct.

The link to the PubChem record is to an INCORRECT structure and should be edited to link to CID:5147169.

The name should be

IUPAC:   (1R,2R,3S,4R,7S,9R,10R,12S,15R)-4,12-Diacetoxy-15-{[(2S,3R)-3-(benzoylamino)-2-hydroxy-3-phenylpropanoyl]oxy}-1,9-dihydroxy-10,14,17,17-tetramethyl-11-oxo-6-oxatetracyclo[11.3.1.0~3,10~.0~4,7~]heptadec-13-en-2-yl rel-benzoate

or

CAS Index: benzenepropanoic acid, beta-(benzoylamino)-alpha-hydroxy-, (2aR,4S,4aS,6R,9S,11S,12S,12aR,12bS)-6,12b-bis(acetyloxy)-12-(benzoyloxy)-2a,3,4,4a,5,6,9,10,11,12,12a,12b-dodecahydro-4,11-dihydroxy-4a,8,13,13-tetramethyl-5-oxo-7,11-methano-1H-cyclodeca[3,4]benz[1,2-b]oxet-9-yl ester, (alphaR,betaS)- —Preceding unsigned comment added by 24.162.249.146 (talk) 01:55, 28 September 2007 (UTC)
 * Hi Antony—I've fixed the PubChem accession number. As for the IUPAC name...which is most adequate? I'd like to see further input on this. As an aside, anyone can edit Wikipedia, you know—wouldn't you like to join? :) Fvasconcellos (t·c) 02:51, 28 September 2007 (UTC)
 * Hi..I tried editing the DrugBox and couldn't so assumed it was locked. Only to discover that I hadn't logged in...oops. Sorry, I would have done it myself. I have pasted the new IUPAC Name in:

(1R,2R,3S,4R,7S,9R,10R,12S,15R)-4,12-Diacetoxy-15-{[(2S,3R)-3-(benzoylamino)-2-hydroxy-3-phenylpropanoyl]oxy}-1,9-dihydroxy-10,14,17,17-tetramethyl-11-oxo-6-oxatetracyclo[11.3.1.0~3,10~.0~4,7~]heptadec-13-en-2-yl rel-benzoate

I hate the fact that I have introduce spaces to not expand the Drug Box--Tony27587 13:36, 1 October 2007 (UTC)

Contentious edit being broadcast (possible BLP and POV issue)
Please do not revert the edit to which this Talk section refers, paragraph 3 of lede; rather, refute soundly the following arguments made with regard to POV and article accuracy issues, beforehand. (On unexplained reversion, I will elevate immediately for administrative review. Since this relates to two living chemists, I am treating this as, in essence, a BLP issue.)

The lede sentence mentioning only the Holton group in the synthesis of paclitaxel is being edited for the following reasons:

 * use of the word "notable" is unacceptable at Wikipedia with regard to discussing individual accomplishments, apart from reporting use of the word, about an individual, by others; it is specifically listed as an example of puffery, and is forbidden at WP:PEA, see, and its use here is just that, absent a citation using the term;
 * to list only the Holton group, whose article was first to be accepted for publication, and not list the Nicolaou group, whose article was first to be published, when both appeared essentially simultaneously in 1994, and to do so when other areas of reporting and Wikipedia represent the accomplishments as comparable and simultaneous (see further below), is to to represent history in a biased manner; compare the third paragraph of the lede, here, to the following (from elsewhere in Wikipedia):

 * in doing the foregoing, to further exclude mention of the ferment of broad paclitaxel synthetic activity taking place concurrently with the profound efforts of these two groups—this choice, alongside the "notable" wordchoice and the Nicolaou omission, further support the conclusion that the current description in the lede misrepresents the history of the period;
 * to do so when other Wikipedia articles and the remainder of this article  do not do so, reinforces the point;
 * these points are all the more critical, given that this is both a high profile article, and the point-article for a series of articles on this natural product and on its activities; and finally
 * to limit mention to one research team is to contradict the preponderance of scientific reporting, including from the most prominent American scientific news source, where the report of this matter, appearing in Science, by Flam, is entitled "Race to synthesize taxol ends in a tie." See.

I am therefore editing the relevant sentence in the lede to reflect a substantiated, POV-neutral perspective, as it appears already within Wikipedia (e.g., here: ), without in any way marginalizing the important and fine work of the Holton group. This edit removes the critical POV issue, better reflects the remainder of the article and related articles at WP, and makes the text neutral with regard to this exciting chapter in natural products total synthesis.

Note/disclaimer (a la Nature Publishing Group requirements): I have trained under none of the fine synthetic chemists now named in this revision of the article, have sat on faculty or boards with none, have consulted alongside none, but have done so under and alongside their peers, and have otherwise studied and taught their work (since 1990). See my User page (click on Edit to ungrey) if you have questions as to my credentials and expertise, with regard to making this edit.

Le Prof Leprof 7272 (talk) 22:39, 30 May 2014 (UTC)

Non-independent source being moved from Production section to Talk
…until a suitable independent citation can be found to support the text content. The text content is presumed accurate, but it is being labeled by a tag, until a replacement is found. The non-independence of the cited article is asserted, as it is a university communications venue for FSU, a primary academic participant in the race to synthesize and semi synthesize paclitaxel, and the text statement it supports regards this race. Here is the reference removed, with its accompanying sentence (lead markup bracket removed): Please help find a suitable independent source for this statement, with page numbers; because the statement regards a claim of a position taken by a US government agency, its independent verification should be a straightforward matter. Le Prof Leprof 7272 (talk) 14:32, 2 June 2014 (UTC)
 * The view of the NCI, however, was that the CNRS route was not practical. ref name="Stephenson_2003">
 * This had as a further result, another portion of text being without citation, to which a tag was also added:
 * "BMS took the process in-house and started to manufacture paclitaxel in Ireland from 10-deacetylbaccatin isolated from the needles of the European yew."
 * Le Prof Leprof 7272 (talk) 17:40, 2 June 2014 (UTC)

Total synthesis material separated from Production section
… fully referencing the new section, and making it essentially neutral based on the sources. (In the Production section, the TS material was a diversion, and confusing as to the point; as now is noted and cited, TS was never seen as a means to production.) With this change, the lede mention of the Holton paclitaxel TS is now ready to appear as a summary statement of the neutral text that appears later in the text (to be done soon).

Also done with this edit: removed all red wikilinks, fixed a "cite error" problem (in earlier reference 27, see next action), added various citation tags in the production section (!), and touched up the closing BMS section vis-a-vis quotations and reference to the naming of Taxol® and its being assigned paclitaxel as an INN.

Discuss changes here, please. (I will seek immediate admin involvement if there is a reversion without discussion.)  Le Prof Leprof 7272 (talk) 17:29, 2 June 2014 (UTC)

Contradiction between lede and later section tagged
The coverage of endophyte production in the section "Commercially viable paclitaxel production" contradicts in its conclusion the conclusion implied in the lede about the same matter. Needs to be reconciled, changing one or the other. (The lede cannot be cock sure positive, while the body of the article is ambivalent in conclusion.) Le Prof Leprof 7272 (talk) 02:13, 3 June 2014 (UTC)

Editing lede today
The announcement of intent to edit the lede vis-a-vis its ongoing POV issue, see, has been available here and has been without comment for over three weeks now. The issue of the contradiction between lede and text body on fungal production of paclitaxel has also been posted for this much time. As a result of the lack of any rebuttal or discussion, I am making the edit to the lede this morning, to remove the POV issue and to make the lede fully consistent with the body of the text. (Given the due diligence taken in addressing this potentially controversial edit, and the lack of any interest on anyone's part over these weeks, I will respond to a reversion with immediate request for Administrator attention.) Cheers, hope this closes this odd, longstanding lede issue. Le Prof Leprof 7272 (talk) 14:31, 24 June 2014 (UTC)

Moved images to Talk for duscussion

How are these images truly relevant to the section in which they appeared? (Where do we say that yew bark is used in the production of the precursor of paclitaxel?) What is the point of the emphasis on easily renewable yew needle and possible culture sources, if we are going to illustrate the production section with bark stripping?

What in fact is the actual current biomaterial used in production, and is use of these images misleading to actual process? Since I cannot provide immediate sources, I am not answering my own questions. Neither should the images be reintroduced, unless sources are placed that make clear they are truly related to the Section (how paclitaxel is actually produced), and not fanciful, theoretical associations with the topic. Le Prof 73.210.155.96 (talk) 12:08, 13 March 2017 (UTC)
 * The first sentence says this was how it used to be made.. Doc James  (talk · contribs · email) 17:35, 13 March 2017 (UTC)

Wording
Should we go with

 * "Use during pregnancy may result in harm to the fetus"
 * "Use during pregnancy may result in harm to the baby"

As we are writing for a general audience and the two terms are used interchangeably in this content I support the use of baby. Others thoughts? Doc James (talk · contribs · email) 22:30, 3 May 2017 (UTC)
 * What is the route of transmission? Your edit-summaries note "Yup the problem occurs in the baby when it is born." and "The negative affects are typically only noticed when the baby is born." The former statement is a little stronger--that whatever the drug does, it doesn't happen until birth, rather than happening in utero and remaining undetected until birth. Which ref actually supports the fetal/at-birth specific details, vs just that it is in Pregnancy Category D? DMacks (talk) 23:04, 3 May 2017 (UTC)
 * The FDA uses "baby" not "fetus" for the med classification here.
 * CDC uses "unborn baby" Doc James  (talk · contribs · email) 23:52, 3 May 2017 (UTC)
 * I agree that the right choice might depend upon the kind of harm (e.g., stillbirth vs premature birth).
 * I always dislike using "the fetus" when we mean "the embryo" or "the future-baby at all developmental stages from conception through birth". This drug likely affects all stages of development, but it's unwanted effects are worst in the first trimester.  As a result, I'd prefer "unborn baby" to "fetus".  It would also be appropriate to include some idea of what the harms are (premature birth or low birth weight; miscarriage or deformity if given during the first trimester), and how common they are (not as common as you might think for cytotoxic chemotherapy, no worse than other options, 92% healthy babies).  WhatamIdoing (talk) 02:59, 4 May 2017 (UTC)
 * Thanks User:WhatamIdoing happy with "unborn baby" and will look at adding more details regarding harm to the body of the article. Doc James  (talk · contribs · email) 03:18, 4 May 2017 (UTC)
 * That sounds reasonable. Including "unborn" avoids any possible implication that it is a "during delivery" effect (compare to major mode of mother->child HIV transmission) or a later effect involving nursing or child having some sort of withdrawal. DMacks (talk) 05:21, 4 May 2017 (UTC)
 * I would be cautious about use of "baby". Sure, call it an "unborn baby" at 8 months gestation, but in the first trimester, calling it a baby has an anti-abortion bias. NHS Choices tends to use "embryo" and "foetus" in its patient information, but does also use "baby"/"unborn baby" (although I couldn't find anything specifically on this drug). Bondegezou (talk) 09:22, 4 May 2017 (UTC)
 * If this was being used in the context of abortion I would more understand the concern. But this is about potential complications of the use of this medication in pregnancy. Doc James  (talk · contribs · email) 23:58, 4 May 2017 (UTC)
 * agree w/ Doc James on this point--Ozzie10aaaa (talk) 14:53, 5 May 2017 (UTC)
 * "This drug likely affects all stages of development, but it's unwanted effects are worst in the first trimester. As a result, I'd prefer "unborn baby" to "fetus"." -How is "unborn baby" a better description during the first trimester than "fetus". That's not logical at all.  "Developing fetus" is what it is at that stage, and saying that would also reflect the fact that paclitaxel is causing abnormalities of development. It doesn't matter whether the context is abortion or not, saying "baby" would still affect how people think about it.188.29.165.33 (talk) 12:12, 5 May 2017 (UTC)
 * According to Embryo, In humans, a pregnancy is generally considered to be in the embryonic stage of development between the fifth and the eleventh weeks after fertilization, and is expressed as a fetus from the twelfth week. Are fetus and baby truly used interchangeably? This is not the impression given by the article Infant. • • • Peter (Southwood) (talk): 16:19, 5 May 2017 (UTC)
 * The article Infant states before birth, the term "fetus" is used. However if the developmental deformities from taxol occur mostly in the first trimester, that's actually an overlap between "fetus" and "embryo". So either 'developing embryo' or 'developing fetus' would be logical terms.  188.29.165.33  (can't sign normally, the IP keeps changing)
 * Or we can use common English and simply stick with "unborn baby" Doc James  (talk · contribs · email) 21:06, 7 May 2017 (UTC)
 * That phrase is the most biased; like saying 'it's unborn but it's a baby anyway'. That wording implies an advanced development, even though during most of the first trimester we're talking about, is a stage too early to even be called a 'fetus'. 188.29.165.33
 * If we actually say what the effects are, we can reword to avoid this sentence structure altogether. For example, "use of paclitaxel during pregnancy is associated with an increased risk of [some symptom]". I'm having trouble finding anything though...the label says Pregnancy Category D, meaning there is evidence of risk, but only based on rat/rabbit studies and by extrapolation from its biochemical targets. Conversely, the label states that there are no controlled human studies. And a 2012 systematic review on human reports found no effect.10.1093/annonc/mdp517 DMacks (talk) 21:25, 7 May 2017 (UTC)
 * Maybe say "use of paclitaxel during pregnancy may be associated with an increased risk of [some symptom]", because it's not been proven to happen in humans. Otherwise I agree. 188.29.165.33
 * This wording is more informative: Animal studies suggest increased fetal demise, decreased birth weight and delayed ossification if used during pregnancy;  however a review suggests it is safe in humans during the 2nd/3rd trimester.    "188.29.165.33"  — Preceding unsigned comment added by 92.40.248.12 (talk) 17:31, 8 May 2017 (UTC)
 * The lead should provide an overview. There is not much evidence as it has not been well studied. rxlist states "It could harm the unborn baby."
 * A specific discuss of the evidence should occur in the body of the article IMO.
 * The product monograph from the FDA website says "TAXOL can harm your unborn baby." Doc James  (talk · contribs · email) 04:18, 9 May 2017 (UTC)
 * It says 'baby' once, in the lay-speak "What should I tell my healthcare provider before receiving TAXOL?" section of the monograph. In comparison, the "Pregnancy" section uses 'fetus' once and 'fetal' three times. There's no real need to dumb it down. LeadSongDog come howl!  20:15, 10 May 2017 (UTC)
 * Maybe we use "baby" once in the lead. And use the more technical terms in the body. As a source for the general population there is nothing wrong with using common language rather than more technical language. Doc James  (talk · contribs · email) 23:43, 10 May 2017 (UTC)
 * It's not 'technical', it's accurate. Wikipedia is an encyclopedia, not a leaflet.92.40.249.102 (talk) 00:39, 11 May 2017 (UTC)
 * WP is a online encyclopedia written for a general audience yes. Doc James  (talk · contribs · email)

01:17, 11 May 2017 (UTC)
 * This doesn't mean Wikipedia should call a first-trimester fetus/embryo a 'baby' just to have 'common language'. 92.40.249.102 (talk) 14:30, 11 May 2017 (UTC)
 * These all repeat what the manufacturer's insert States. And they're all based on theoretical assumptions (edit: and animal studies). But the evidence in humans points mostly in a different direction. The sentence in the lead shouldn't be misleading. "188.29.165.33" — Preceding unsigned comment added by 94.197.121.114 (talk) 13:45, 9 May 2017 (UTC)
 * The evidence in humans is nearly non existence as one is not allowed to do human trials in pregnant women unless animals studies are showing it is relatively safe. If animals studies show it likely is not human studies are nearly impossible to do. Doc James  (talk · contribs · email) 01:45, 10 May 2017 (UTC)
 * The review did say it's relatively safe during the second and third trimester. If you don't like that, then say 'use during pregnancy may cause birth defects'. 94.197.120.77 (talk) 13:08, 10 May 2017 (UTC)
 * Which review? Would be happy with "use during pregnancy may cause birth defects" Doc James  (talk · contribs · email) 15:32, 11 May 2017 (UTC)
 * I didn't make it very clear; I was referring to https://www.ncbi.nlm.nih.gov/pubmed/22907101 - which two other users posted, one then describing it as "a 2012 systematic review on human reports found no effect." — Preceding unsigned comment added by 5.148.17.228 (talk) 18:55, 11 May 2017 (UTC)

Others thoughts on "use during pregnancy may cause birth defects"? Should we go with that? Doc James (talk · contribs · email) 22:19, 11 May 2017 (UTC)
 * Crickets. Crickets everywhere. Since nobody human is saying anything I'll go ahead and insert that line. 188.29.165.59 (talk) 12:58, 14 May 2017 (UTC)

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