Matthieu Clément

Eric Rougier

Jean-Philippe Berrou

François Combarnous

Dominique Darbon

"What's in the middle": Scratching beneath the surface of the middle class(es) in Brazil, Côte d'Ivoire, Turkey and Vietnam

The term "middle class" is increasingly used to qualify the mass of people in developing countries who are neither poor nor rich and share consumption patterns historically associated with the western middle class. However, what differentiates them from the ideal-typical middle class, as well as the extent to which emerging middle classes differ across developing countries, has only been marginally documented by economists to date. This article proposes to scratch beneath the surface of the so-called middle-class that is burgeoning in developing countries by documenting the commonalities and differences hidden by the allencompassing term of "middle class" for a set of developing countries exhibiting different levels of income, economic structures and socio-political systems: Brazil, Côte d'Ivoire, Turkey and Vietnam. Relying on quantitative and qualitative micro-economic data, our paper compares the objective characteristics (occupation, education, income), behavior and subjective expectations of the people standing in the middle of the income distribution in the four countries. Four main research questions structure the paper. Where is the middle? How is the middle specific? Who is in the middle? What does the middle aspire to? Results show that the middle-income group in each country covers distinct realities. Although some similar characteristics and behaviors are observable, our results reveal a strong heterogeneity within each national middle class, with no fewer than four to seven socio-economic subgroups, and strong country-specific traits as most of the subgroups are deeply rooted in the country's specific historical trajectory. In each country, our analysis also unveils a pattern of bipolarization between a rather affluent and stable middle class and a "new" or more vulnerable one. Finally, middle class members appear to be characterized by an individualist positioning and the absence of a marked political commitment, challenging the common assumption that developing countries' middle classes are agents of political change.

Introduction

The rapid densification of the intermediate segment of developing economies' income distribution is certainly a major event of the early 21 st century [START_REF] Knauss | The myth of the global middle class, globalization's fallback success story[END_REF]. This large and heterogeneous group, constituting the bulk of what banks and consulting groups now identify as the "global middle class", 1 is one of the winners of the globalization-led growth decades of the 1990s and 2000s, as their average income increased by more than 60% between 198860% between and 200860% between , according to Milanovic (2016)). According to recent estimates by [START_REF] Kharas | The unprecedented expansion of the global middle class. An update[END_REF], approximately two thirds of the more than 3 billion people constituting the global middle class (defined as people with daily income of between $11 and $110 in 2011 PPP) came from developing countries in 2015. The rapid extension of the developing countries' middle class during these two decades, notably in Asia [START_REF] Brunke | Global topics 8 billion consumers. How to reach emerging market consumers with new strategies[END_REF][START_REF] Kharas | The unprecedented expansion of the global middle class. An update[END_REF], was supposed to sustain global consumption and save markets in a context of slowing consumption in developed countries [START_REF] Kharas | The emerging middle class in developing countries[END_REF]. 2 Based on the historical record of the impact of middle-class consolidation in advanced countries during the 20 th century [START_REF] Lipset | Political man. The social bases of politics[END_REF][START_REF] Moore | The social origins of dictatorship and democracy[END_REF][START_REF] Adelman | Society, politics, and economic development: A quantitative approach[END_REF][START_REF] Landes | The wealth and poverty of nations[END_REF], high expectations are associated with the middle-class momentum in developing countries. First, it is supposed to bring about the development of domestic markets for diversified goods and services (ADB, 2010; AFDB, 2011; [START_REF] Castellani | The Latin American middle class. Fragile after all? IDB Working Paper[END_REF]. Larger middle classes are also expected to increase national saving and investment and to prompt institutional reforms, supporting private property right protection and investments in durable assets [START_REF] Loayza | Do middle classes bring institutional reforms?[END_REF][START_REF] Birdsall | Does the rise of the middle class lock in good government in the developing world[END_REF][START_REF] Wietzke | The developing world's "new middle classes": Implications for political research[END_REF]. A larger middle class is also associated with the diffusion of social norms promoting all kinds of individual 1 [START_REF] Wilson | The expanding middle: The exploding world middle class and falling global inequality[END_REF]), McKinsey Global Institute, (2012[START_REF] Kharas | The unprecedented expansion of the global middle class. An update[END_REF]), Merrill Lynch Global Research (2016). 2 The size of the global middle class was recently estimated to have shrinked by 54 million (Pew Research Center, 2021) during the current Coronavirus pandemics. Yet, it is too early to know whether the trends observed during the two latter decades will persist after the crisis. investments, supporting the consolidation of social status or increasing intragenerational and intergenerational income and social mobility [START_REF] Doepke | Occupational choice and the spirit of capitalism[END_REF]. Lastly, the expansion of the middle class in developing countries is also supposed to promote social cohesion by pushing for redistribution policies that offset the traditional dualism between a vast mass of poor and a small elite, and to bring political stability by promoting prodemocratic values [START_REF] Boix | Democracy and redistribution[END_REF][START_REF] Acemoglu | Economic origins of dictatorship and democracy[END_REF].

These "high expectations" have not been fully supported by the empirical literature on developing countries to this point. Micro-economic evidence has essentially pinpointed the vulnerability of large portions of developing countries' middle class [START_REF] Banerjee | What is middle class about the middle classes around the world?[END_REF][START_REF] Ravallion | The developing world's bulging (but vulnerable) middle class[END_REF][START_REF] Dang | Welfare dynamics measurement: Two definitions of a vulnerability line and their empirical application[END_REF]. Moreover, while the reality and usefulness of the socio-economic category of "poor" is not disputed, that of "middle class" is highly multifaceted and appears to be unconsolidated in the eyes of development economists and social scientists. Indeed, four definitional approaches to the middle class can be identified in social sciences. The income-based economic approach, mainly mobilized by economists, merely defines the middle class as non-poor non-rich households and is mainly focused on the drivers and impacts of their economic consolidation [START_REF] Easterly | The middle class consensus and economic development[END_REF][START_REF] Milanovic | Decomposing the world income distribution: Does the world have a middle class?[END_REF][START_REF] Banerjee | What is middle class about the middle classes around the world?[END_REF][START_REF] Ravallion | The developing world's bulging (but vulnerable) middle class[END_REF]. The sociological approach, based on the identification of the attributes of social status and class consciousness through education or occupation, is inspired by the Marxian and Weberian definition of social classes and essentially focuses its attention on social structures and domination [START_REF] Cramer | Views of economic inequality in Latin America[END_REF]Torche and Lopez-Calva, 2012;[START_REF] Haggard | Income, occupation, and preferences for redistribution in the developing world[END_REF][START_REF] Cheeseman | No bourgeoisie, No democracy? The political attitudes of the Kenyan middle class[END_REF]. The subjective approach, largely inspired by cultural sociology and relying on shared life-styles and behavior, has the forging of close social relations and a sense of shared identities as its main objects of analysis [START_REF] Burbidge | Can someone get me outta this middle class zone?!' Pressures on middle class Kikuyu in Kenya's 2013 election[END_REF][START_REF] Mercer | Middle class construction: Domestic architecture, aesthetics and anxieties in Tanzania[END_REF]. Lastly, the behavioral-managerial approach observing consumption habits focuses on the middle class of "global" consumers and on their market behavior [START_REF] Guarin | New middle-class consumers rising powers: Responsible consumption and private standards[END_REF][START_REF] Belbag | The new middle class in emerging markets: How values and demographics influence discretionary consumption[END_REF]. Each approach only partially sheds light upon the middle-class reality and on the stakes raised by its consolidation and expansion. Economists, for example, insist on income level and on various behavioral traits related to the consumption structure or the labor market position, without necessarily referring to social identification or social class structures, conflicts and issues which can be highly relevant in apprehending the political agency of the middle class [START_REF] Loayza | Do middle classes bring institutional reforms?[END_REF][START_REF] Birdsall | The (indispensable) middle class in developing countries[END_REF][START_REF] Birdsall | Does the rise of the middle class lock in good government in the developing world[END_REF]. On the other hand, by insisting more on social class and identification, the sociological and behavioral-managerial approaches tend to overlook the aggregate impact of social structures or identities (Darbon and Toulabor, 2014;[START_REF] Melber | The rise of an African middle class: Myths, realities and critical engagements[END_REF][START_REF] Benza | Nuevas clases medias: acercar la lupa[END_REF]. Put differently, mixed approaches are needed to reconcile and articulate the different faces of the segment of the population considered as middle class in developing economies.

The lack of supporting evidence of the economic and political expectations of the middle class can also be explained by the fact that the occupational, behavioral and ideational attributes of developing countries' middle-income earners do not exactly reproduce what was constitutive of the middle class's social status in advanced countries [START_REF] Wietzke | The developing world's "new middle classes": Implications for political research[END_REF]. Indeed, poverty reduction in developing countries has generally been associated with a structural shift into informal self-employment [START_REF] Banerjee | What is middle class about the middle classes around the world?[END_REF][START_REF] Resnick | The political economy of Africa's emergent middle class: Retrospect and prospects[END_REF] or low productive service-related jobs [START_REF] Mcmillan | Globalization, structural change, and productivity growth, with an update on Africa[END_REF][START_REF] Rodrik | Premature deindustrialization[END_REF]. Likewise, economic success is not necessarily related to the education level, as tertiary-educated young adults struggle to find their way in society through formal well-paid skilled jobs [START_REF] Campante | Why was the Arab world poised for revolution? Schooling, economic opportunities, and the Arab Spring[END_REF]. Analyzing the size and scope of developing countries' middle-class through the shared perceptions and expression of class consciousness is undermined by the respondent's lack of anchoring in an interpersonally comparable standard of wellbeing [START_REF] Wietzke | The developing world's "new middle classes": Implications for political research[END_REF]. When they consider their position in their own country's relative income distribution, middle-income earners tend to consider that what is usually referred to as the middle class in developed countries corresponds more to economic elites in their country. These patterns have certainly contributed to blurring people's identification with the middle class in developing countries and to casting doubts on the idea of the middle class's collective agency in this very context. Far from constituting a genuine social class that has reached a minimum degree of internal consistency, the reality of the middle class could well be limited in many developing countries solely to the aggregation of microeconomic behavioral patterns that spur economic transformation in the long run. Furthermore, the sociopolitical contexts and economic situations are extremely diverse across countries, making comparisons of the different national middle classes highly perilous and requiring that a very prudent analysis in terms of generalization.

Based on these statements, our modest objective in this paper is to scratch beneath the surface of the catch-all category of the middle class in developing countries, to identify who exactly the people standing in the middle of the income distribution are, and what their typical behavioral and ideational traits are. More specifically, this paper combines parallel quantitative and qualitative analyses of the socio-economic traits, behaviors and expectations of middle-income earners conducted on four distinct and heterogeneous developing countries (Brazil, Côte d'Ivoire, Turkey and Vietnam) by adopting a comparative lens. Inspired by the dramatic contrast method in historical sociology [START_REF] Skocpol | Visions and methods in historical sociology[END_REF], the paper's fundamental assumption is that studying four countries that have little in common (in terms of geographical zones, levels of development, social structures, historical trajectories and systems of government) might offer information on both the common and the idiosyncratic characteristics of the middle classes in developing countries. Indeed, the four developing countries that are compared (Brazil, Côte d'Ivoire, Turkey and Vietnam) represent four different regions (Latin America and the Caribbean, Sub-Saharan Africa, Europe and Central Asia and East Asia and Pacific) 3 and cover a wide range of levels of economic development, productive structures and political contexts. For example, the official discourse in Brazil and Turkey, stressing the importance of supporting the middle class, finds no significant translation into public policies, with the expansion of the middle-class being largely supported by market dynamics and the private sector in these two countries. 4 3 Based on PovcalNet data from the World Bank, Figures S1 to S4 in the Supplementary Material compare the income distribution of each of the four sampled countries to the income distribution of their respective region of membership. The cumulative distribution functions that are reported confirm that Côte d'Ivoire, Turkey and Vietnam are fully representative of their region in terms of income distribution. We observe a gap between the cumulative distribution curves for Brazil and the Latin American and Caribbean region but the shape of the two curves is very similar, thus confirming that Brazil's income distribution is quite comparable to that of its region. 4 Yet, the political objectives behind the promotion of national middle classes are different in the two countries. The Workers' Party (PT) that governed Brazil at the time of our analysis and survey had put the middle class at the top of its agenda, as the very existence of this population demonstrated the legitimacy and effectiveness of the anti-poverty and macro-economic policies they had adopted. In Turkey, Based on this original methodology, the present comparative research yields various noteworthy findings and answers to the four aforementioned questions. First, our analyses confirm that the delineation of the middle class is difficult, particularly from a comparative perspective, as the middle-class category conveys very distinct realities in the four countries investigated. Second, our investigations reveal that each national middle class has important socio-economic and behavioral characteristics (e.g. intermediate levels of education, feeling of upward socio-economic mobility, consumerist behavior, investment in private education, indebtedness, etc.) that make the middle so specific, especially compared to the poor and the rich. Third, by identifying four to seven specific socio-economic subgroups across the four countries, our comparative analysis sheds new light on the strong internal socio-economic heterogeneity of each national middle class. Moreover, in all four countries, our analysis highlights a pattern of polarization of the middle classes into one stable and consolidated segment and another more vulnerable segment remaining exposed to shocks and constrained in terms of socio-economic behavior. Fourth, our qualitative surveys emphasize a common aspiration "for better" in all four countries, though expressed differently across countries.

They also provide evidence of individualistic aspirations that, combined with the strong internal fragmentation of national middle classes, may explain the limited political commitment of middle-class people and may thus question the capacity of the middle-income group in the four countries to constitute a genuine socio-political class united by common policy preferences.

The paper is structured as follows. The methodology and data are presented in Section 2. The four following sections describe the main findings regarding our four research questions:

Where is the middle? (Section 3); How is the middle different? (Section 4); Who is in the middle? (Section 5); and What does the middle aspire to? (Section 6). Section 7 concludes.

Methodology and data

Our comparative analysis is based on an original methodology combining both quantitative and qualitative materials. In order to analyze these different materials comparatively and comprehensively, a similar mixed quantitative-qualitative approach was implemented for the four countries. Our approach consisted in successively mobilizing data from recent national household surveys and original data from qualitative surveys conducted among a sample of middle-class households in each country.

The quantitative analysis first seeks to identify the structure of the middle class in the four countries and to reveal its potential heterogeneity by using data from existing nationally implemented by the GSO (General Statistics Office of Vietnam) for Vietnam. Based on these surveys, our method 5 is sequential and combines the income-based and sociological definitions of the middle class by (i) first using information on income in order to delimit a middle-income group, that is, a group of households located in the middle of the income distribution, 6 and (ii) then exploring the heterogeneity of this middle-income group by implementing a mixed classification procedure on five socio-economic categorical variables characteristic of the household head: education, occupation, employment status, institutional sector and multi-activity practices. This mixed classification procedure combines nonhierarchical and hierarchical clustering methods and is relevant in the presence of a large number of individuals for whom it is impossible to directly apply hierarchical clustering (due to intensive calculation requirements). 7 In each country, the group of middle-income earners is then classified into internally homogeneous, yet clearly distinct groups. In order to better characterize them, we finally compare the different group means for a large set of socioeconomic variables including those used for the cluster analysis.

The qualitative analysis adds to the description and comparison of the four countries' middle classes by analyzing how the behavior and aspirations of the middle class identified during the quantitative analysis differ across subgroups and countries. In 2017-2018, semi-structured interviews on the behavior and practices of individuals as well as on their perceptions and preferences were conducted in each country on 25-30 households sampled via quotas 5 See [START_REF] Bonnefond | In search of the elusive Chinese urban middle class: An exploratory analysis[END_REF] for the first implementation of this method. 6 Our goal here is not to identify precisely the number or percentage of people in the middle class (given the lack of consensus on the choice of the income range), but rather to delimit a set of middle-income people that is consistent with other estimates. To improve consistency, most of the intervals used in the literature to identify the middle-income class will be tested and compared. 7 The selected partition (the number of groups retained within the middle-income class) results from the analysis of the dendrogram and the objectives of maximizing the ratio between the inter-group variance and the intragroup variance (Calinski-Harabasz index) and minimizing the similarity index between the groups (Davies-Bouldin index).

respecting the different segments of the middle class identified in the quantitative analysis (see Table S1 in the online Appendix for more information). To allow for spatial heterogeneity, interviews in the four countries were conducted in two distinct places: a large metropolitan area of the country (Rio de Janeiro, Abidjan, Istanbul and Hanoi) and a secondary city distant from it (Fortaleza, Soubré, Gaziantep and Nam Dinh). These qualitative interviews allow us to investigate how the fact of belonging to different segments of the national middle classes does or does not induce specific socio-economic behaviors (consumption, credit and debt practices, investment in education, residential strategies) and aspirations and expectations (subjective feeling about socio-economic mobility, expectations and preferences regarding the state and public policies, political identities). The comparability of the information collected was ensured by the design of a standardized survey, with the interview grids nonetheless being adapted to the specificities of the different contexts observed (specific vocabulary, local particularities, etc.).

Where is the "middle"? Monetary identification of the middle-income group

The delineation of the middle class is a delicate task, especially in the set-up of a comparative analysis. Three main income-based approaches (relative, absolute and mixed) are used in the economic literature to identify middle-class households. The relative approach defines the middle class as the population located in the middle of the income distribution, with intervals most often being constructed from median income or average income: between 75% and 125% of median income [START_REF] Birdsall | Stuck in tunnel: Is globalization muddling the middle[END_REF], between 50% and 150% of median income [START_REF] Castellani | Being 'middle class' in Latin America[END_REF] or between 100% and 250% of average income [START_REF] Song | Social stratification and mobility among Chinese middle class households: An empirical investigation[END_REF]. The absolute approach, primarily used for international comparisons, is based on absolute intervals expressed in PPP (Purchasing Power Parity) dollars. As the middle class is supposed to start where poverty ends, many intervals are constructed with a lower boundary of $2 per capita per day (in PPP): $2-$10 (Barnerjee and Duflo, 2008), $2-$13 [START_REF] Ravallion | The developing world's bulging (but vulnerable) middle class[END_REF] and $2-$20 (ADB, 2010;[START_REF] Castellani | Being 'middle class' in Latin America[END_REF]. However, as households with per capita income just above $2 remain highly vulnerable to external shocks (ADB, 2010), the lower limit of $10 has also been used in the literature: $10-$20 [START_REF] Milanovic | Decomposing the world income distribution: Does the world have a middle class?[END_REF], $10-$50 [START_REF] Ferreira | Economic mobility and the rise of the Latin American middle class[END_REF] or $10-$100 [START_REF] Kharas | The emerging middle class in developing countries[END_REF][START_REF] Kharas | The unprecedented expansion of the global middle class. An update[END_REF]. This higher cut-off is probably better grounded in the Weberian conjecture that households should enjoy a certain minimum level of economic security to be considered as middle class [START_REF] Wietzke | The developing world's "new middle classes": Implications for political research[END_REF]. Lastly, the mixed approach consists of combining an absolute lower boundary and a relative upper boundary [START_REF] Birdsall | The (indispensable) middle class in developing countries[END_REF][START_REF] Bonnefond | In search of the elusive Chinese urban middle class: An exploratory analysis[END_REF]. The interval proposed by Birdsall (2010) has a lower limit of $10 and an upper limit corresponding to the 95 th percentile of the income distribution.

Table 1 presents the percentage of households within the middle-income group in each country for twelve overlapping income intervals covering the three approaches described above. The detailed statistics (including the proportion of the poor and rich groups) can be found in Tables S2 to S5 in the online Appendix. As expected, our computations lead to very heterogeneous middle-class sizes in the four countries: the percentage of households included in the middle-income group ranges from 26.1% to 86.6% in Brazil, from 1.4% to 46.2% in Côte d'Ivoire, from 21.3% to 92.3% in Turkey and from 22.6% to 87.5% in Vietnam.

Insert Table 1

Since our analytical perspective is comparative, the choice of a relevant interval is a crucial issue. We choose a mixed interval combining an absolute lower boundary and a relative upper boundary. In line with Birdsall (2010: 7), the upper boundary is set at the 95 th percentile of the income distribution (P95), for this relative limit excludes "that portion of the population within a country whose income is most likely to be from inherited wealth or based on prior or current economic rents (…) and thus less associated with productive and primarily labor-based activity than for the non-rich". The choice of the lower limit is much more problematic because the shape of the left part of the income distribution is radically different in the four countries, as evidenced by the Kernel curves of income distribution (Figures S5 to S8 in the online Appendix). This is confirmed by the indicators reported in Table 2, showing large variations in the poverty ratio across the four countries: only 2.7 % of the population earns below 4$ a day in Turkey, against 22.5% in Vietnam and 68.5% in Côte d'Ivoire. Likewise, mean per capita income is close to $25 per household per day in Brazil and Turkey, against approximately $10 in Vietnam and $5 in Côte d'Ivoire.

Insert Table 2

Two subgroups of countries clearly emerge from Table 2' Our results therefore confirm that the delineation of the middle-income class is a delicate task in developing countries, making international comparison a risky exercise, particularly in the presence of large wealth and income stratification disparities between countries.

How is the middle specific?

The middle-income group identified in section 3 has important socio-economic and behavioral characteristics that should now be described in two steps. First, using data from the four nationally representative household surveys, we compare the middle-income stratum with the two other income segments, the "poor" and the "rich", for five dimensions that are usually mobilized to describe social classes. We complete this quantitative description using information from the qualitative surveys to document how the perception of upward intra-and inter-generational mobility is another important socio-economic marker of middle-class identity. Second, still based on qualitative data, we explore a series of behavioral traits related to consumption, investment in education, residential strategies and debt that we interpret as highly characteristic of the sampled countries' middle-income segments.

"Between the poor and the rich": the middle is different in terms of socio-economic characteristics and mobility

Tables A1 to A4 in the Appendix compare the three groups identified on the basis of the income criterion ("poor", "middle class" and "rich") for the five classification variables describing the socio-economic characteristics of the household head: education (highest level attained), occupation, employment status, institutional sector and multi-activity practices.9

Broadly speaking, these tables show that heads of households belonging to the middle-income group tend to occupy an intermediate position between "poor" and "rich" for most of the classification variables.

In all four countries, middle-class household heads are overrepresented in secondary education levels, especially when compared to the poor and the rich, while tertiary level educational attainment remains concentrated among the wealthiest group and thus can be viewed as a clear demarcation line between the rich and the middle class. In terms of occupational status, interesting differences across countries are emphasized. In Brazil, Côte d'Ivoire and Vietnam, household heads from the middle-income group tend to be proportionally more occupied as service employees and workers compared to the two other income groups. In Turkey, these two occupations are more characteristic of the poor while heads from the middle stratum tend to be relatively more represented among the retired and inactive category. Likewise, although (and as expected) the proportion of farmers is the greatest among the poor group in the four sampled countries, it is worth noting than in Côte d'Ivoire and Vietnam, the share of middle-class household heads engaged in agricultural activity is relatively high (reaching 26.9% and 37.4%, respectively). Another interesting point is that the highest positions (managers, executives and entrepreneurs with employees) remain highly associated with membership of the rich group in all four countries. Finally, descriptive statistics related to the institutional sector reveal an income gradient associated with informal employment (i.e. an increasing share from the rich to the poor) in Brazil and Turkey. In contrast, in Côte d'Ivoire and Vietnam, informal employment appears to be a distinctive feature of middle-class membership (with an even greater share among the middle-income group than among the poor). This might suggest that informality may be a way of gaining access to the intermediate income group in these two countries, characterized by lower levels of development compared to Brazil and Turkey.

Our qualitative surveys are also informative of the specific features of the middle-income group. Although these surveys did not include poor and rich respondents (hindering comparisons across groups), they shed light on one interesting trait common to almost all middle-class respondents: the feeling of upward intra-and inter-generational mobility. Indeed, most of the surveyed household heads reported that their situation had improved, with respect to both their parents' and their own past experience.

In Brazil, almost all interviewees emphasized that they had benefitted from upward intergenerational changes in living conditions compared to their parents' generation. While rural origins were fairly common for their parents, most respondents reported having migrated to metropolitan areas (Rio and Fortaleza). Significant intergenerational changes in education were also pointed out by the respondents, with illiteracy having vanished among their family members and peers, with the number of individuals who could complete secondary level and above increasing at the same time. As for employment, respondents underlined that they experienced higher job mobility than their parents, who were primarily involved in agriculture and handicraft activities and tended to be stuck in one type of occupation and location.

Vietnamese respondents also reported that they enjoyed much better living conditions than their parents' generation. However, the qualitative interviews documented sharp differences in the nature of job mobility between generations, with the former generation of middle-class household heads having been exclusively employed in state agencies and state-owned enterprises, while household heads from the current generation were able to start selfemployed work in a market economy. Patterns of spatial mobility have also constantly evolved across generations: interviewees reported that middle-class household heads from the former generation were compelled by the Communist party to move to nearby towns to get jobs in administrations or parastatals, while their grown-up children could move to more distant and bigger cities.

In Turkey, where the interviewees, especially in Istanbul, also reported high intergenerational social mobility, three different patterns were described. The first pattern of social mobility is based on the household's spatial mobility from a rural to an urban setting, while the second one is based on improving education. The qualitative survey therefore reports a strong feeling among middle-class household heads that social change and modernization in Turkey are mainly driven by individual improvements in education coupled with rural-urban migration.

As for the second pattern, almost all interviewees stressed the primary importance of education for their offspring, therefore corroborating the feeling that "if you study, you will have a better life", the validity of which they have experienced in their own lives. The third pattern of upward social mobility, albeit less frequent, is marriage. As we were explicitly told, women, especially those from rural areas, can experience immediate social mobility by marrying a man who is richer and more educated than them. Côte d'Ivoire constitutes an exception as regards the subjective feeling of socio-economic mobility in the middle class. Interviewees expressed relative satisfaction with their living conditions, feeling "neither rich nor poor", but mainly expressed strong concerns about their vulnerability to shocks. This point will be discussed in section 5.2.

"Neither poor nor rich": some behavioral traits are highly characteristic of the middleincome segments

In all four countries, similar behavioral patterns have been identified in the qualitative surveys. These behavioral constants relate to consumption, investment in human capital, residential strategies and indebtedness and they are highly specific of the middle class, as the literature explains.

(Limited) consumerist behavior. Our qualitative surveys show that the adoption of modern consumption (equipment goods, ITC, leisure, etc.) is an obvious marker of middle-class membership in all four countries. Although interviewees generally agree that conspicuous consumption is the symbol of individual success and prosperity, the adoption of such consumption patterns appears more significant in Brazil and Vietnam than in the two other countries. Brazilian middle-class households stand out by their marked consumptionorientated behavior, notably in terms of technological equipment. All surveyed households own at least one mobile phone, often of the latest generation, while most of them also have access to the Internet and have a computer. Consumerism also concerns leisure, as interviewees express strong demand for recreational activities (sports, cinema, theatre, etc.).

Moreover, half of the households interviewed report travelling, some of them regularly, others infrequently. In Vietnam, respondents confirmed that consumption patterns have significantly changed for middle-class households. They reported having gradually changed their consumption habits, with their purchases progressively shifting from the informal to the formal sector and combining the old custom of daily shopping in small local marketplaces for groceries with the new way of shopping in supermarkets once or twice a month for goods and equipment or for child entertainment. The use of mobile phones, laptops and internet connections has also become common among Vietnamese middle-class households, and online shopping is developing rapidly in urban areas due to the improvement of internet connections. Our interviews also provide evidence of a modernization and diversification of consumption patterns in Côte d'Ivoire, though to a lesser extent than in Brazil and Vietnam. Surprisingly, given the country's relatively high income level, the diffusion of modern consumption patterns in Turkey is less widespread than in Brazil or Vietnam. Although the survey points to car ownership as a clear marker of middle-class membership in Turkey, all interviewees revealed a modest diversification of their consumption expenditures. They reported that the bulk of their expenditure is still on food and that they try to limit it. "Free time" activities are almost non-existent, with only a few interviewees mentioning sports activities, tourism travel or visits to family members outside their city of residence. Overall, the life of the Turkish middle classes is divided between home and work.

Private education and health expenditures.

The strong aspirations for their children's futures and the priority given to investment in education and health, notably through the private sector, are common traits of middle-class households in the countries under study. For all interviewees, education and health expenditures constitute important markers of middle-class identity and reflect aspirations for intergenerational promotion. This behavioral trait is typical of the middle class, as already emphasized by [START_REF] Banerjee | What is middle class about the middle classes around the world?[END_REF]. This is particularly the case in Turkey, where most interviewees stated that children are at the center of their life and explained that expenditures, savings, the use of spare time or plans for the future all revolve around their children. The shortcomings of the public education system are widely recognized by interviewees in the four countries investigated, even though they also admitted that significant efforts have been made over recent decades to improve access to education for all. In Côte d'Ivoire, the denunciation of the poor quality of the public education system is unanimous. As one interviewee declared, "School is the poor relation in Côte d'Ivoire". In Brazil, negative judgments relate exclusively to public primary and secondary education and the main criticisms were that the system "leaves much to be desired", delivers "poor quality education", has "teachers lacking qualifications and commitment", suffers from "significant degradation", is "unfair", etc. In Vietnam, middle-class households are also aware of the poor quality of public schools, which they explain by the inadequacy of human resources in a school system that has grown rapidly over the past decade. In all countries, middle-class households therefore seek to compensate for the shortcomings of the public education system by enrolling their children in private schools (Brazil, Turkey, and Côte d'Ivoire) or in extracurricular private lessons (Vietnam). Similar use of the private sector as a substitute for a failed or absent public sector is also observable for health. Adhesion to private health insurance plans is, at least in Brazil and Turkey, another distinctive feature of middle-class households.

Strategies of residential differentiation.

Our survey has highlighted that residential strategies and housing choices constitute another crucial dimension of social differentiation, especially in Turkey and Brazil. In these two countries, middle-class consciousness is expressed through expensive strategies of spatial clustering with middle-class peers. In Turkey, the proliferation of gated communities on the edges of large cities has become one of the major features of Turkish urbanization and of middle-class spatial spread over recent decades [START_REF] Pérouse | Zenginliğin mekânda yeni yansımaları: İstanbul'da güvenlikli siteler[END_REF]. Interviewees explained such residential choices by a demonstration effect and by the quest for a quiet and unpolluted living environment. In Brazil, residential choice is primarily related to the insecurity issues that are pervasive in Brazilian cities. Middle-class families are pushed to live in "bunkerized" and permanently guarded housing complexes (condominios), surrounded by walls and barbed wire and also offering private amenities such as swimming pools, sports halls, games and party rooms, garages, etc.

Indebted middle classes?

While modern consumption and investment patterns tend to be partially financed by debt in all four countries, indebtedness concerns prove to be more significant in Brazil and Turkey. In Brazil, just under half of all households in our sample are truly indebted. Respondents also declared having recourse to loans with automatic repayments through payroll deductions (empréstimos consignados), which gained momentum during the terms of President Dilma Rousseff (2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016) when private credit expanded significantly. In Turkey, the qualitative survey revealed that indebtedness has been an essential driver of the development of (moderately) ostentatious consumption in recent years. Private debt for purchasing durable goods or investing in housing has been explicitly prompted by AKP's economic policies, with the consequence that the Turkish middle class is now heavily indebted, as expressed by one respondent:

"We are all in the same situation: we borrow, we have credit cards, we have a lot of debts. We do not stop paying off our debts; we repay again and again. This is the picture. Everyone, from the most modest to the wealthiest, without exception, everyone is in debt" (Male,38 years old,restaurant owner).

The increasing use of credit cards (revolving credit and/or cash reserves), whose fundamental characteristic is to increase "expendable" income, has ensured the self-financing of

Who is in the middle? A closer examination of the internal structure and consistency of the middle-income group

In this section, we examine the internal structure of the middle-income segments by implementing a cluster analysis of middle-income households in each of the four countries on the five same socio-economic characteristics mentioned above. Our objective is to reveal the potential heterogeneity of the middle-income group in relation to each country's specific historical trajectories of economic development, social stratification and political transformation. This cluster analysis also sheds light on the extent to which the different components of the middle-income group are vulnerable. Lastly, the responses to the qualitative field surveys are exploited to illustrate how that heterogeneity is also perceptible in terms of behavioral traits.

"Together, yet so different": the middle is socio-economically fragmented

Distributions of the classification variables for the different middle-class subgroups identified by the cluster analysis in the four countries are reported in Appendix tables A5 to A8, while distributions for additional characterization variables are reported in Tables S6 to S9 in the online Appendix. In order to facilitate the reading and comparison of the results, the main characteristics of the different subgroups of each national middle class identified by the cluster procedure are summarized in Table 3.

Insert Table 3

First, Table 3 shows that the middle class is highly fragmented in all four countries. Recall that the clusters identified for each country are data-driven and group together the household heads that look the most similar from the point of view of the five socio-economic dimensions used for clustering, while at the same time being the most dissimilar from those in the other clusters.

For Brazil, seven subgroups are identified: (1) retired and inactive (30% of the whole middle- (5) unpaid workers (7%); and (6) farmers (27%). Interestingly, the cluster analysis suggests that there is no one differentiated and homogeneous group of middle-class entrepreneurs, contrary to what could be predicted by the models of middle-class formation in 19 th -century Europe and North America [START_REF] Doepke | Occupational choice and the spirit of capitalism[END_REF]. In other words, entrepreneurship does not constitute a line of identification within middle-class households. In all four countries, entrepreneurs are scattered across several groups, according to the characteristics of their firm or sector of activity. In contrast, being an employee in the formal private or public sector does constitute a clear line of demarcation between middle-class households. In line with [START_REF] Banerjee | What is middle class about the middle classes around the world?[END_REF], our results confirm that more than the development of entrepreneurial activities, the fact of having a steady salaried job and regular labor income emerges as one major dimension of the large divide across households within the middle class.

Each national middle-income stratum is thus characterized by the existence of four to seven very specific clusters. In addition, the relative size and the socio-economic structure of these middle-class subgroups is often highly country-specific and pretty consistent with their historical trajectory of class formation.

Brazil, for example, has long been known for its polarized social structure associating a very small elite with a large mass of poor people and a small-sized intermediate class, composed of public-or private-sector professionals and managers [START_REF] Salata | The formation of the middle class in Brazil: History and prospects[END_REF]. The latter social group finds its counterparts in subgroups 2 and 3 identified by the cluster analysis.

In Côte d'Ivoire, the formation of the middle class is also anchored in the country's economic and political history, as it goes back to the "economic miracle" of the 1960s and 1970s. Then, the combination of Houphouët-Boigny presidency's active promotion of export-oriented agriculture with high international prices for cocoa and coffee prompted the emergence of a strongly idiosyncratic middle class of planters, and a new middle class of intermediate-and higher-level professionals capturing positions in the public and politically connected private sectors [START_REF] Savina | Les en-haut des en-bas et les en-bas des en-haut : Classes moyennes et urbanisation à Abidjan (Côte d'Ivoire)[END_REF]. Although over the 1980-2010 period, the social structure inherited from the "economic miracle" was disrupted by a succession of economic and political crises, the group of farmers (group 1) accounting for 25% of the current Ivoirian middle-income group and the group of employers, managers and executives (group 4) are still present in the national middle class.

Our classification analysis for Turkey is also consistent with the historical trajectory of the country's economic policies and social stratification [START_REF] Yılmaz | Türkiye'de orta sınıfı tanımlamak: Ekonomik düzeyler, siyasal tutumlar, hayat tarzları, dinsel-ahlaki yönelimler[END_REF]. Over the last twenty years, the "old middle class" of highly educated and urban professionals (mainly in group 1 of pensioners and in group 4 of employers and executives) has constantly lost ground. The "new middle class" that emerged in the meantime, particularly in Anatolian intermediate cities and rural areas (see Table S7 in the online Appendix) as a result of the rapid expansion of an export-oriented manufacturing sector and President Erdoğan's and AKP's anti-poverty policies [START_REF] Oguztimur | Turkey's entrepreneur weapons: The driving forces behind Anatolian tigers[END_REF], is captured in groups 2 and 3 (industry and service workers, small entrepreneurs and large farmers) of our classification.

The legacy of history is more confused in Vietnam, notably because Communist authorities have consistently avoided referring to "social classes" since the revolution. Nonetheless, public sector middle-and high-level employees identified by our analysis (groups 2 and 3) likely concentrate what remains of the country's pre-communist historical middle class. Over the past three decades, the country has achieved sustained growth and outstanding progress in poverty reduction after the Doi Moi reforms initiated in 1986, which encouraged rapid private sector development and large inflows of foreign investment, allowing the formerly urban and rural poor to enter the middle class massively. Specialized farmers in the Mekong area included in group 6 (see Table S5 in the online Appendix) are direct beneficiaries of these reforms (OECD, 2014).

"No longer poor, yet still vulnerable": the middle is polarized

The feeling of vulnerability expressed by most middle-class respondents is somewhat confirmed by the pattern of polarization that is apparent in the results of the cluster analysis. Indeed, our analysis reveals in all four countries a pattern of bipolarization between a rather affluent and urban middle class, characterized by stable and high-skilled jobs, and a more fragile middle class characterized by lower income levels, lower education levels and more unstable and/or less productive jobs (informal, agriculture).

Irrespective of the country's level of income per capita, the upper component of the middle class is characterized by the combination of high education levels, stable and formal employment and modern consumption patterns (ownership of durable goods, leisure, connectivity, etc.). The relative size of this group remains limited and, surprisingly, proves to be fairly homogeneous across economic development levels: it ranges from 17% of the middle class in Brazil (groups 2 and 3) and Turkey (group 4), to 21% in Côte d'Ivoire (groups 3 and 4), and 23% in Vietnam (groups 2 and 3). Equally interesting is the fact that civil servants are overrepresented in the upper component of each national middle class. This convergence points to the crucial role played by the public sector in the promotion of "traditional" affluent and educated middle classes in all four countries.

In contrast, the existence of a subgroup of "middle" middle-class household heads marks a clear divide between Côte d'Ivoire and Vietnam on the one hand, and Brazil and Turkey on the other hand. In the latter two countries, a large subset of middle-class household heads is characterized by relatively stabilized occupational profiles (formal workers or employees) coupled with relatively low income and education levels. Our estimations show that such "middle" middle classes account for 44% of the whole middle class (27% of the whole population) in Brazil (groups 5 and 6) and 31% (23% of the whole population) in Turkey (group 3), which suggests that the degree of polarization of the middle-income group may decrease with the level of economic development or of institutional consolidation of middleclass household situations.

In the four countries studied, the share of the vulnerable middle class therefore remains relatively high. Our estimations suggest that it might account for a large proportion of the middle class in Côte d'Ivoire and Vietnam (79% and 77% respectively, and for Vietnam, corresponding to more than half of the whole population) and, to a lesser extent, in Turkey and Brazil (with respectively 52% and 39%). Our analysis shows that the vulnerable middle class is primarily composed of households with atypical occupational profiles. First, a group mostly composed of retirees was identified in the four countries. The share of this group in the national middle class ranges from between 14% and 15%, for Vietnam and Côte d'Ivoire respectively, to 32% and 39%, for Brazil and Turkey. This indicates that the size of this group increases with the level of income per capita and with the extent of formal pension coverage.

Second, a group of middle-class farmers was identified in Côte d'Ivoire, Turkey and Vietnam, which is unsurprising given that the agricultural sector employed respectively 40%, 38.6% and 18.4% of the working population in these three countries in 2018, according to World Bank data.10 Moreover, in these three countries, it should be noted that, besides landowning farmers, a fringe of low-educated, multi-active, highly vulnerable agricultural workers are also found in the rural middle-class subgroup. Third, our cluster analysis emphasizes that informal workers constitute a differentiated segment of the middle class in three of the four countries under study. While the weight of this group remains limited in Brazil (only 7% of the middle class), it is much larger in Côte d'Ivoire (39%) and in Vietnam (29%), where a large portion of informal workers are entrepreneurs.

Our qualitative materials also provide interesting insights into the vulnerability of broad ranges of the national middle classes. In Côte d'Ivoire, respondents from the subgroup of farmers reported shocks such as family member losses, inheritance issues, burned fields or natural hazards that had had a persistent adverse impact on their lives, and the difficulties of recovering from them and returning to their former living conditions. The macroeconomic crisis that hit the country in 2017 was also perceived by most respondents as a threat to the continuation of the trend of upward mobility towards the middle class that had been recorded from the 2000s onward. Most of them also bemoaned the recent deterioration of their situation, notably as regards employment and wages. Similar cases of microeconomic vulnerability were reported by respondents in the three other countries. For instance, Vietnamese interviewees whose income depends exclusively on market conditions and who are excluded from social protection also expressed concern about their household's vulnerability to economic downturns or personal hazards. In Brazil, various respondents also acknowledged that they feared the socio-economic consequences of the economic crisis that had struck the country at the time of the survey.

Perhaps more optimistically, our results also show that it is possible to join the middle class through informal farming activities and non-farming entrepreneurship and employment in developing countries. It is true that the static data we use in this paper make it tricky to describe the underlying entrepreneurial dynamics at work. However, what the different surveys suggest is that informal activities cover very heterogeneous situations ranging from subsistence to opportunity entrepreneurship in the four countries under study. Beyond these differences, it may confidently be inferred that middle-class informal entrepreneurs have activities that have allowed them to avoid poverty more or less durably, even though they face precarious living conditions and are vulnerable to shocks because they lack insurance protections. This interpretation is somewhat confirmed by [START_REF] Grimm | Informal entrepreneurs in Western Africa: Constrained gazelles in the lower tier[END_REF], who show that African informal entrepreneurs have developed genuine entrepreneurial skills through multiactivity, risk-taking, investment behaviors or profit seeking. Yet they are quite vulnerable and struggle to develop their activity and improve their productivity, because they are forced to use their skills in highly unstable and constrained environments.

"Constrained and unconstrained" middle classes: the income gradient and behavioral contrasts

Responses to the qualitative surveys conducted in each country are mobilized to confirm that, principally due to the large socio-economic gaps across groups, some specific domains of households' behavior also appear to be heterogeneous within each national middle class. Our analysis suggests that the differential capacity of the different subgroups to meet their consumption or investment expectations is mainly explained by highly contrasted financial conditions characterizing them.

First of all, such heterogeneity concerns consumption patterns, especially in Côte d'Ivoire and Vietnam where the consumerist behavior typical of the middle class is only observable in the small-sized upper segment of the middle class. In Côte d'Ivoire, only a few respondents report adopting fully westernized consumption patterns (e.g. shopping in malls in Abidjan). The majority of Ivoirian middle-class households talked of their difficulties in making ends meet, even for food expenditures. In Vietnam, our qualitative survey shows that access to ICT remains largely constrained for the most vulnerable middle-class households.

Equally, expenditures on private education and health also mask disparities between the different components of the middle classes in the four countries. In fact, our surveys show that investment in private education and health is only accessible to households in the upper segment of the middle classes. Although they also expressed a strong desire to invest in their children's human capital, respondents from the most vulnerable components of the national middle classes state that they remain highly dependent on poor-quality public services (notably in education, adult training and health) because of their financial constraints, therefore supporting the findings of [START_REF] Birdsall | The strugglers: The new poor in Latin America?[END_REF] for regions other than Latin America.

Our qualitative interviews are also informative of the existence of a socio-economic gradient regarding residential strategies, though contrasted across countries. As previously explained, in Brazil and Turkey, spatial clustering in gated communities is an important marker of middle-class membership, but it only remains accessible to the wealthy and upper segments of the middle class. In the two other countries, the situation looks different insofar as housing quality and budgets are significantly lower, public planning and housing policies are less effective and housing and real estate strategies are less guided by self-esteem. In Côte d'Ivoire, for example, our survey shows that the intensity of housing and residential issues is highly dependent on the household's location. Because of high real estate pressure in Abidjan, broad inequalities can be observed across the different components of the small Ivoirian middle class. Household heads from the most vulnerable middle-class subgroups reported living in outlying districts so as to limit rents. In Vietnam, most of the interviewed household heads also complained about the poor quality of their housing and said they hope to be able to invest more in their property in the near future in order to improve its quality and size.

Lastly, as for credit and indebtedness, the interviewees reported very contrasted attitudes in Brazil and Turkey, with Côte d'Ivoire and Vietnam being much less concerned by indebtedness issues. In Brazil, the fact that credit use primarily concerns the lower segments of the middle class suggests that private debt constitutes both a strategy against and a potential source of vulnerability. Although the households surveyed were not concerned by insolvency, it is interesting to note that some of them reported having stopped using credit cards and feel increasingly cautious about indebtedness. In Turkey, the interviewees reported different attitudes concerning bank credit. While the oldest respondents generally expressed strong reservations and apprehensions about indebtedness and credit, most respondents declared that they borrow only exceptionally, for expensive purchases (house, car), and evoked fears related to the instability of interest rates. By contrast, a third group of middle-class households, generally from the most vulnerable subgroups, reported living in a permanent spiral of debt and borrowing in order to maintain their level of consumption. Across the board, members of the Brazilian and Turkish middle class make a clear distinction between debt used to acquire durable goods and housing, considered as a form of savings, and other, more dangerous forms of debt, described by a Turkish interviewee as 'that used by people who cannot spend without going into debt' and considered as an indication of economic vulnerability.

To conclude with this section, our analysis has identified a pattern of bipolarization that appears to be shared by the four countries, albeit rooted in each country's historical trajectory of social stratification. Everywhere and regardless of the level of economic affluence, the historical middle class, who secured social status by seizing opportunities of consolidation through financial, social and cultural capital accumulation and transmission, is juxtaposed with the upwardly mobile "neo"-middle-class who recently escaped poverty while remaining vulnerable to shocks or personal hazards. The vulnerability of developing countries' neomiddle classes has already been largely emphasized in the economic and sociological literature [START_REF] Ferreira | Economic mobility and the rise of the Latin American middle class[END_REF][START_REF] Melber | Africa and the middle class[END_REF][START_REF] Dang | Welfare dynamics measurement: Two definitions of a vulnerability line and their empirical application[END_REF][START_REF] Zizzamia | Vulnerability and the middle class in South Africa[END_REF][START_REF] Zambrano Roman | An emerging but vulnerable middle class: A description of trends in Asia and the Pacific[END_REF][START_REF] Benza | Nuevas clases medias: acercar la lupa[END_REF].

What does the middle aspire to?

In the different developing countries studied in this paper, people in the middle share some common economic and social aspirations, regardless of their income and socio-economic position. Nevertheless, a majority of the people interviewed during our qualitative surveys also have in common the priority given to their own interest and their relative disinterest in political engagement. We believe that these characteristics contribute to a finer-grained description of what middle-class people actually look like in developing countries and of what kind of changes they might bring about in the future.

A common but idiosyncratic "aspiration for better"

Our comparative analysis of the qualitative interviews shows that among the four national middle classes a common aspiration for "better" is largely observable. This aspiration is associated with a capacity to project themselves toward a better future through various forms of investment in housing, production equipment or schooling that is highly typical of the middle class. Indeed, despite considerable differences in average income across countries, all four national middle classes are diversifying their consumption towards superior needs such as education after having secured their immediate and basic needs. The emphasis placed on merit, self-promotion and effort by respondents can also translate into a marked preference for private education and for private investment in land and real estate in the four countries investigated. However, despite such shared ideational traits across countries, the aspiration for "better" also refers to distinct realities across countries.

Our qualitative surveys show that in Brazil and Côte d'Ivoire, aspirations for security are important, even for the upper parts of the middle classes. In Brazil, one of the most violent countries in the world, middle-class respondents expressed a strong demand for security. Almost all interviewees feel unsafe: "We walk in the street constantly fearing an attack", "we can do nothing about the bandits", "crime is lurking everywhere", "violence is taking over the streets and neighborhoods", etc. Furthermore, they claimed that they themselves or members of their family had already been victims of violence, most of them attacks and robberies, along with one case of kidnapping for ransom and two cases of homicide. Recriminations generally focus on the failure of public security forces and include "a very slow police force, which leaves something to be desired", "inefficient", "deficient", "disordered and lost", "in a critical state", "non-existent", "contributing to the chaos", etc. In Côte d'Ivoire, security concerns are also important. After the 2000s, marked by a strong military-political conflict and the separation of the country into two, the middle-class households interviewed expressed their support for the peace process which would arrest the economic decline and stop the State security forces from disintegrating. However, our qualitative interviews show that while the process of conflict resolution and the "justice of the victors" has maintained a strong feeling of resentment in one part of the middle class, the fear of a new political crisis has tended to favor the status-quo and the absence of political reaction from the middle class.

In Turkey and Vietnam, aspirations around security are less pronounced than in Brazil and Côte d'Ivoire. However, our interviews in these two countries reveal an interesting point regarding what aspirations to better may mean in terms of the "modern lifestyle". Urban respondents from these two countries have in common the search for a balance between modernity and tradition. In Vietnam, our semi-directed interviews show that members of the middle-income group who migrated to the big cities are keen to find a harmony between their modern urban life and the rural life of their parents and ancestors, notably through frequent returns to their village of origin. Social values thus remain strongly influenced by tradition.

The same is true in Turkey, particularly in Gaziantep where most interviewees have not broken away from the villages and small towns in which they were born. New urban dwellers have not abandoned farming and sometimes pursue an agricultural activity in their village of origin for self-consumption and/or income diversification. Lastly, as shown in several of the interviews conducted in Gaziantep, the preservation of a link with the village of origin provides resources that are still important in coping with the economic difficulties inherent to city life. Even households with higher income levels remain marked, in their way of life and their values, by the rural world from which they come and which they tend to perpetuate in the city.

An "individualistic" class with fuzzy and heterogeneous political identities

Interestingly, our four qualitative surveys point to the absence of a marked political commitment among interviewees, challenging the common assumption that developing countries' middle classes are willing to serve as agents of political change.

The survey depicts middle class members as being characterized by an individualist positioning, essentially driven by the quest for material comfort (living conditions, housing, etc.) and security for their personal and familial strategies of socio-economic promotion, rather than by any form of collective identity that would push them to prioritize generalinterest political issues such as democratization, equality or social justice. The absence of political commitment does thus not necessarily mean that middle classes are de-politicized or do not occasionally take part in collective mobilization. Indeed, many respondents voiced criticisms of the political sphere, albeit to varying degrees in the four countries. Moreover, respondents from all middle-class subgroups across the four countries also reported being concerned about property rights and about the unfair costs imposed by rampant corruption.

For [START_REF] Wietzke | The developing world's "new middle classes": Implications for political research[END_REF], this growing concern is the consequence of the accumulation of durable assets by developing countries' middle classes.

In Brazil, our survey took place in a political context tarnished by corruption scandals involving politicians at the three levels of government (federal, estadual and municipal) and including the two most recent former presidents, Lula da Silva and Dilma Rousseff, as well as business leaders. While Brazilians' opinion of politics has worsened with the proliferation of "affairs", interviewees reported having had a very negative image of their representatives and authorities for a long time, regardless of which government was in power. Respondents spoke freely and spontaneously, using their own words and expressions. The adjectives frequently associated with politics include "terrible", "corrupt", "horrible", "deceitful", "filthy", "wrong", "worsening every day", a "total negation" of what it should be. Several respondents said they were "sad" and "revolted". They criticized politicians for "forgetting their promises", "not being serious" and "diverting public funds". The reality of small-scale everyday corruption in administrative formalities was also recognized by most of respondents and some of them said that the general population contributes to the pervasiveness of such practices. Daily arrangements with the law (o jeitinho) have created a climate conducive to the development of illicit practices for decades.11

In Côte d'Ivoire, middle-class interviewees also reported their rejection of the corruption of the elites as well as the increase in inequalities characterizing a "two-tier Côte d'Ivoire". The gap between optimistic discourses on the double-digit growth and the worsening of living conditions for the majority of the population is often denounced:

"One class drives cars costing 50 million FCFA while people get poorer.

Injustices are too great!" (Male, 44 years old, service employee).

In Vietnam, respondents from the upper segment of the middle class (public servants and business owners) also expressed their fear that rampant corruption might end up undermining both economic efficiency and the Communist Party's political legitimacy. They were nonetheless pleased that more people could now have access to information about corruption cases through social networks. These ideas are clearly stated by one respondent: "Many of the government officials have undermined the party, and some trillions of dong have been lost. Corruption is really terrible. Information on corruption is shared a lot on the internet (...) Nowadays, corruption is more common and cruel. Actually, while about 50% of the money invested in a project is properly used, about 50% is misappropriated (...)" (Male, 55 years old, university lecturer).

However, aspirations to policy change and democratization remain limited and were never mentioned as priority goals by Vietnamese respondents. Middle class members are very reluctant to engage in collective activities that could catalyze their discontent, for reasons that are not clearly stated. Closeness to the party-state and a preference for stability might explain their lack of political involvement and weak demand for democracy.

In Turkey, the position vis-à-vis the political sphere is very peculiar. Although our qualitative interviews do not reveal any political commitment among middle class households, one of the salient features of today's Turkish middle class is undoubtedly its strong political polarization.

The divide between the secular "old middle class" and the conservative and Islamic "new middle class" has become particularly acute in the past two decades. While the "old middle class" tends to identify with the center-left and supports the CHP (Republican People's Party), the "new middle class" supports AKP. The division is so deep that the interviewees either strongly applauded or strongly criticized past developments in such areas as education, health, social security, taxes, corruption and security of property and people, depending on their political position with respect to AKP.

Despite the very contrasted historical trajectories of the four national middle classes, a common trend can be detected. In all four countries, the emerging middle groups favor political regimes that guarantee stability and political order and in so doing allow them to develop their personal projects and to enjoy advances and economic development for themselves and their children. This explains the differentiated choices of the two Turkish middle classes, whose differences in professional activities lead to two types of order. This also explains the incredible volatility of the average Brazilian electorate, and the gap between Ivorian critics and the support for power, embodied by President Ouattara, which incarnates a return to the path of development in order. The Turkish, Ivorian, Brazilian and Vietnamese cases are "shining examples" of the fact that the middle classes will be able to influence both an authoritarian regime and a democratic regime as long as the latter ensures them the order that is favorable to their project.

Conclusion

The objective of the paper was to scratch beneath the surface of the catch-all category of middle class in developing countries using an original quantitative and qualitative method and a comparative approach. Four research questions have guided our analysis.

The first one deals with the delineation of the middle class. Our comparative work confirms how difficult this delineation is given the large wealth gap and income distribution disparities between the four countries investigated. It proved impossible to define a single monetary range applicable to all four contexts. While the definition of the upper bound could be harmonized by using the 95 th percentile of the income distribution, the choice was made, after an in-depth examination of the income distribution in the four countries, to split our sample into two pairs of countries: Turkey and Brazil for which the lower limit was set at $10 per capita per day in PPP, and Vietnam and Côte d'Ivoire for which this limit was set at $4. On this basis, the weight of households belonging to the middle-income group ranges from 26.5% in Côte d'Ivoire to 75.4% in Turkey. Brazil (61.4%) and Vietnam (72.5%) lie in between, with the middle-class share being highly sensitive to the choice of the lower bound in Vietnam. Interestingly, our findings are consistent with previous works showing that large shares of developing countries' non-poor population belong to the income range below $10 [START_REF] Edward | Estimating the scale and geography of global poverty now and in the future: How much difference do method and assumptions make?[END_REF]. The second research question is about the specific features of people in the middle, especially compared to the poorest and the richest. Quantitative analysis shows that higher education attainment and access to the highest occupations (managers, executives, and entrepreneurs) remain a clear demarcation line between the rich and the middle-income group. We also highlight that informal employment is a distinctive feature of middle-class membership in Côte d'Ivoire and Vietnam. In addition, our qualitative data indicates a common feeling of upward mobility among the interviewed and some similar behavioral patterns regarding modern consumption, investment in private education, residential strategies and financial behavior, among others. The third question deals with the internal structure of the middle-income group in the four countries. Results show the strong internal heterogeneity of each national middle class, particularly with regard to the significant differences existing between them in terms of employment status, level of education or income. Each national middle class is characterized by the existence of four to seven very specific socio-economic clusters. In addition, the relative size and the trajectory of some of these middle-class subgroups is highly country-specific. Such subgroups as the farmersplanters in the Côte d'Ivoire, the Anatolian entrepreneurs in Turkey or the specialized farmers in the Mekong area in Vietnam do not find their counterparts in the other countries investigated. The analysis also reveals a pattern of bipolarization that is both strong and common to the four countries. Everywhere an upwardly mobile "neo"-middle-class that has recently escaped poverty while remaining vulnerable to shocks and constrained in its behavior is juxtaposed with a more established and stabilized middle class. The last question addresses the aspirations or expectations of the people that stand in the middle. A common aspiration for "better" seems to be widely shared across middle-class subgroups and countries. However, this common aspiration translates into very different visions in terms of what better life means in the four countries of our sample (demand for security in Brazil and Côte d'Ivoire, tradition vs modernity in the cases of Turkey and Vietnam, for example). A dominance of individualistic preferences is also observable in the four countries, notably as regards social self-promotion and issues related to private property. Combined with the internal socioeconomic fragmentation of national middle classes, this individualistic stance could explain the absence of political commitment among the interviewees and the difficulties in organizing collective mobilization for and within their middle-income group.

Finally, the results of the present paper suggest that the "middle class" category is just as vague and debatable in our four developing countries as it was and still is in industrialized countries. Many previous studies have proceeded to a transmutation of the term "middle class", consisting in transforming, by a simple process of linguistic requalification, an income group constructed in a purely logical, quantitative and mechanical way, into a very particular social group that can go as far as identifying itself as a social class. Based on our findings, we argue that this might constitute a methodological error. The notion of middle class that is mobilized by the makers of development policies and aid (development banks, governments, experts) is essentially based on the transposition of the historical experiences of Western societies. However, the emergence of the middle classes proves an historical process specific to each society, to the point of leading to very differentiated types of middle classes in developed countries and probably more so in the developing world, as confirmed by our four case studies. Even though common attitudinal or aspirational characteristics could be identified across countries and socio-economic subgroups, this paper shows that the people "in the middle" are first and foremost people from different backgrounds, who are differentiated and divided by levels and types of income, lifestyles, forms of activity, intergenerational ties, social representations and affinities. Therefore, the middle classes are not only very heterogeneous between different developing countries, but also within each country. The subgroups that constitute them do not form a coherent group bound by common values and preferences and congregating around a specific social or political consciousness that would additionally be universal across countries. In fact, middle-income people are both rural and urban (Côte d'Ivoire, Turkey, Vietnam), they are people with both a modern, westernized culture and a more conservative outlook (Turkey), they are people from the official and informal worlds (Côte d'Ivoire, Vietnam), and they include the near-poor, the economically less well-off and the near-wealthy. Combined with individualism, this strong socio-economic fragmentation may well obstruct collective action and political deals within the middle-income group, while facilitating political deals between the higher middle class and the elite. Lastly, our results suggest that political coalitions within the middle class in developing countries could lead to very different outcomes from those leading to the formation of welfare states in advanced economies [START_REF] Wietzke | The developing world's "new middle classes": Implications for political research[END_REF].

Attempting to transpose the "middle class" concept from one context to another elsewhere might therefore expose researchers and policymakers to considerable misinterpretation, as is obvious with African lower middle-income households whose enrichment is still very relative and whose vulnerability is still substantially high [START_REF] Jacquemot | Africa's middle class: Realities, issues and perspectives[END_REF][START_REF] Resnick | The political economy of Africa's emergent middle class: Retrospect and prospects[END_REF]. To assume that because people are in the middle of the income distribution, they are middle-class is a highly debatable bet and one that we question in these four cases. To assert that because they are in the middle, these groups automatically and universally set themselves up as defenders of universal modernity, democracy and social justice is an even more debatable claim, as is also illustrated by our analyses. Now, if the overly general "middle class" category falls flat in developing countries, the question that arises is whether alternative conceptualizations that more accurately fit common characteristics of class formation should be mobilized. We argue that, at least for the most vulnerable components, such conceptual alternatives exist. Indeed, the "neo"-vulnerable middle class is close to the group often referred to as the "floating class" in the literature, as it is composed of households constantly oscillating between poverty and low prosperity and reaching the middle-income group through atypical trajectories including informal occupation and multi-activity [START_REF] Ravallion | The developing world's bulging (but vulnerable) middle class[END_REF]AFDB, 2011). The floating class also echoes the concept of "vulnerable class" promoted by the World Bank and especially developed for the Latin America and Caribbean region [START_REF] Ferreira | Economic mobility and the rise of the Latin American middle class[END_REF]McKinsey Global Institute, 2021;World Bank, 2021). Finally, the notion of strugglers that was also put forward to describe Latin American vulnerable middle classes [START_REF] Birdsall | The strugglers: The new poor in Latin America?[END_REF] is probably more relevant than the mere concept of middle class to describe the position of a large category of middle-income people in developing countries. The strugglers, unlike the wealthiest who evade taxes and the poor who don't pay taxes, are "net payers" through direct taxation while being at the same time more dependent on low-quality public services, especially in education and health, since they lack the income level of the (upper) middle class and the rich class and they benefit much less from public transfer programs than the poorest. This analysis echoes that of [START_REF] Palma | Has the income share of the middle and upper-middle been stable around the 50/50 rule, or has it converged towards that level? The Palma ratio revisited[END_REF] which suggests that the lower-middle (D5-6) and upper-middle groups (D7-9) tend to have very different income/expenditure levels, and therefore very different socio-economic backgrounds and interests in terms of policies and political alliances. The higher-end of the bottom 40% and the lower-end of the middle class are both composed highly vulnerable nonpoor households, those our analysis classifies as the lower-end middle class subgroups. 12 According to Palma, interest alignment and political alliances across the poor, the different sub-groups of the "middle" and the elite are implicitly visible in the level and quality of public goods provision by the government and the extent to which they may provide credible substitute to private market-sourced education and health services for the middle class or in the extent of anti-poor redistributive programs.

Although all these categories fit better with the reality of middle classes in developing countries, they are less attractive than the middle-class one to policymakers, financial and development aid actors and economic advisors, partly because their imaginary substrate is less easily transformed into political mobilization, fresh money or market prospects.

12 Our absolute lower boundary is indeed lower than that, relative (D4), of Palma. Note: In each cell, the first rate is the percentage of the considered group in the middle class while the second rate is the percentage of the considered group in the whole population. Source:

Authors.

  By contrast, the middle class is almost absent from official discourse in Vietnam for ideological reasons, although it has steadily grown for two decades, while it remains largely unconsolidated because of the absence or weakness of policies explicitly targeted on it in Côte d'Ivoire. Four main research questions structure the present paper. Where is the middle? How is the middle specific? Who is in the middle? What does the middle aspire to? The first question is about the definition and delineation of the middle class in terms of income levels. The second question is primarily about what the middle looks like in the sampled countries. Its focus is on the main socio-economic characteristics of the middle and the extent to which the middle is different from the other income groups. The third question relates to the heterogeneity of middle-income segments in terms of socio-economic and behavioral/attitudinal characteristics. Characterizing this heterogeneity should also make it possible to identify to what extent people in the middle are vulnerable. The fourth question focuses on the socioeconomic and political aspirations of the middle-income segment and aims to shed light on commonalities and peculiarities among such aspirations across countries.

  President Recep Tayyip Erdoğan and his party (Justice and Development Party, AKP) have supported the formation of a new Islamic and entrepreneurial middle class at the expense of the old secular middle class since their election in 2002.

  From a methodological perspective, our empirical investigations seek to circumvent the usual difficulties identified in the literature by adopting an original methodology combining income-based, sociological and subjective approaches to the middle class. Microdata from nationally representative household surveys is used to implement a multidimensional identification of the socio-economic structure of the middle class in each country. This quantitative analysis allows us to go beyond the definition of the middle class as a mere income class, as, in addition to income, it mobilizes socio-economic characteristics related to education and employment generally used to describe and differentiate social classes. The quantitative analysis is complemented by a comparative analysis of original qualitative material collected through parallel field surveys conducted in the four countries in 2017-2018, aiming to examine how individual attitudes, perceptions and expectations contrast across middle-class groups and national contexts.

  representative household surveys: the 2014 PNAD survey (Pesquisa Nacional por Amostra de Domicilios) implemented by IBGE (Instituto Brasileiro de Geografia e Estastística) for Brazil, the 2015 ENV survey (Enquête sur le niveau de vie des ménages) implemented by INS (Institut National de la Statistique) for Côte d'Ivoire, the 2014 SILC survey (Survey on Income and Life Conditions) implemented by Turkstat (Turkish Statistical Institute) for Turkey and the 2012 VHLSS survey (Viet Nam Household Living Standard Survey)

  s figures: Turkey and Brazil on one side, and Vietnam and Côte d'Ivoire on the other side. Two different lower boundaries, respectively $10 and $4, are therefore chosen for these two subgroups. Not only are these two lower boundaries commonly used in the literature dealing with developing countries' middle classes, but Table 2's last column also shows that they are pretty consistent with the relative poverty line of 60% of the median income, respectively $11.2 and $8.3 for Turkey and Brazil and $1.3 and $4.4 for Vietnam and Côte d'Ivoire. 8 When defined as the households with daily per capita income between $4 and P95 in Côte d'Ivoire and Vietnam and between $10 and P95 in Brazil and Turkey, the middle income group accounts for 26.4% of households in Côte d'Ivoire, 72.5% in Vietnam, 61.4% in Brazil and 75.4% for Turkey.

  consumption for households marked by a history of very high inflation. Côte d'Ivoire and Vietnam are less affected by indebtedness. In Côte d'Ivoire, in a context of low banking penetration, diversification of income-generating activities (as well as community-based informal finance) is the privileged means for supporting consumption. In Vietnam, multiactivity is also preferred to debt to finance new consumption needs because of the strong political constraints placed on private credit expansion by the Vietnamese Communist Party.

  income group); (2) intermediate occupations and civil servants (7%); (3) employers, managers and executives (10%); (4) active retirees (2%); (5) workers and farmers (24%); (6) services employees (20%); and (7) informal workers (7%). The socio-economic structure of the Turkish middle class is more homogeneous, since only four subgroups have been identified: (1) retired and inactive (39%); (2) farmers (13%); (3) industry and service workers and small entrepreneurs (31%); and (4) employers, managers and executives (17%). In Côte d'Ivoire, the middle class is made up of five distinct subgroups: (1) farmers (25%); (2) informal workers (39%); (3) employees from the formal private sector (4%); (4) managers, executives and intermediate occupations in the public sector (17%); and (5) retired and inactive (15%). In Vietnam, the middle class is composed of six subgroups: (1) retired and inactive (14%); (2) managers, executives and intermediate occupations in the public sector (7%); (3) selfemployed, employees and employers of the service sector (16%); (4) informal workers (30%);

Table 1 : Percentage of households belonging to the middle-income group according to different income intervals.

 1

	Criterion	Brazil	Côte d'Ivoire	Turkey	Vietnam

Table 3 : Socio-economic structure of middle classes.

 3

	Brazil	Côte d'Ivoire	Turkey	Vietnam

Table A3 : Characteristics (classification variables) of household heads belonging to poor. middle class and rich (Turkey. 2014).

 A3 Note:The middle class is defined as households whose per capita daily income ranges from $10 to the 95th percentile of income distribution. Source: Authors' calculations based on SILC data (2014).

		Poor	Middle class	Rich	Total
		(21.6%)	(75.4%)	(5%)
	Education
	No education	14.9	8.2	1.1	9.3
	Primary education	62.9	47.9	14.0	49.4
	Secondary education	21.0	29.2	20.0	27.0
	Tertiary education	1.1	14.7	64.9	14.3
	Occupation
	No job (retired. inactive. unemployed)	32.9	39.2	24.5	37.1
	Managers. executives	2.0	10.0	52.2	10.4
	Intermediate occupations	1.4	7.3	9.0	6.1
	Service employees	24.6	19.9	9.1	20.3
	Workers	22.2	13.5	1.4	14.8
	Farmers	17.0	10.1	3.9	11.3
	Employment status
	No job (retired. inactive. unemployed)	32.9	39.2	24.5	37.1
	Paid employees	42.9	40.7	51.4	41.7
	Self-employed without employees	22.6	15.8	8.1	16.9
	Self-employed with employees	1.2	3.7	15.9	3.8
	Unpaid workers	0.5	0.6	0.1	0.6
	Institutional sector
	No job (retired. inactive. unemployed)	32.9	39.2	24.5	37.1
	Formal	32.9	44.0	65.8	42.7
	Informal	34.2	16.7	9.7	20.2
	Multi-activity
	Yes	6.2	5.3	5.3	5.5
	No	93.8	94.7	94.7	94.5

It should be noted that the level of poverty in Côte d'Ivoire is so high compared to the other three countries that a lower boundary of $4 excludes a certain number of non-poor households from the middle-income class, thereby leading to an underestimation of this group.

Despite differences due to the different methodologies used in the four national household surveys, we try to make variables comparable across all four countries. However, it should be noted that the nature of the employer (private or public) is not identified in the SILC survey for Turkey. Moreover, as it does not appear to be a relevant differentiating factor, we made the choice of excluding multi-activity from the cluster analysis in the case of Brazil (see Section 5).

Note that in Turkey, although there is no independent group of informal workers, more than 80% of the group of farmers is informal (in the sense of not registering with social security institutions).

The term jeitinho is commonly used in Brazil to describe small, everyday methods for getting around the law such as bribes, tips, exchanges of services, etc.