1 Background: The Weirdest People in the World

The idea that cognition might vary across cultural and linguistic groups is of course not new (see, e.g., Cole 1996). Famously, the linguists Edward Sapir, a student of Boas, and Benjamin Whorf, a student of Sapir, hypothesized that the syntactic structure of a language shapes speakers’ thoughts (Sapir 1921; Whorf 1956), a hypothesis now known as the “Sapir-Whorf hypothesis.” As Whorf put it (1956, 212):

The categories and types that we isolate from the world of phenomena we do not find there because they stare every observer in the face. On the contrary the world is presented in a kaleidoscopic flux of impressions which have to be organized in our minds. This means, largely, by the linguistic system in our minds.

It is notoriously unclear, and it has been long debated, what exactly Sapir and Whorf were asserting (e.g., Kay and Kempton 1984), but despite its vagueness it has inspired, and still inspires research in cognitive science (e.g., Lucy and Shweder 1979; for discussion, see Fessler and Machery 2012), including about color perception (e.g., Berlin and Kay 1969; Rosch Heider and Olivier 1972; Davidoff et al. 1999; Regier and Xu 2017) and spatial orientation (e.g., Pederson et al. 1998).

For all this interest in the possible variation of cognition across cultural and linguistic groups, the modal research in cognitive science continued to rely on samples of convenience, mostly made up of students in American universities. This practice was decisively challenged in 2010, when Joe Henrich, Steven Heine, and Ara Norenzayan published a revolutionary article, “The Weirdest People in the World?,” in Behavioral and Brain Sciences. Giving voice to decades of consensus in anthropology and synthesizing the lessons of 30 years of cultural psychology, from the seeds planted by modern cultural psychologists like Michael Cole, Harry Triandis, Shinobu Kitayama, Hazel Markus, and Richard Nisbett, Henrich and colleagues reviewed a wealth of evidence that many cognitive and perceptual processes vary across cultures. Even more influential and more controversial was the idea that the psychology of people in Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies differs from that of the rest of the world. Finally, Henrich and colleagues noted that contemporary psychology was unable to describe and explain this variation since it was mostly studying participants from WEIRD societies (for an updated version of this argument, see Barrett 2020a, b).

The impact of Henrich and colleagues’ article has been enormous: It has been cited more than 10,000 times in slightly more than a decade; the acronym “WEIRD” has entered into the mainstay of psychology; and behavioral scientists are more sensitive to the cultural variation of psychological and behavioral phenomena. But the revolution is unfinished: The study of how culture influences cognition remains unsystematic; the choice of cultures that are compared is often a matter of convenience rather than derived from theoretical principles (Barrett 2020a, b); and the contrast between WEIRD populations and the rest of the world might have outlived its usefulness.

Cultural variation is not only significant for the behavioral sciences; it also matters for philosophy. In an influential article, Steve Stich had already argued that cultural variation in reasoning might threaten some theories of rationality such as L. Jonathan Cohen’s (1985, 131; emphasis in the original):

Why should we not expect that cognitive competence will vary just as much as linguistic competence? The only answer I can find in Cohen’s writing is a brief suggestion that cognitive competence may be innate. Yet surely this suggestion is entirely gratuitous. Whether or not individuals, social groups, or cultures differ in their cognitive competence is an empirical question, on all fours with the parallel question about linguistic competence. It is a question to be settled by the facts about intuitions and practice, not by a priori philosophical argument. And while the facts are certainly far from all being in, I am inclined to think that studies like those reviewed at the beginning of this paper, along with hundreds of others that might have been mentioned, make it extremely plausible that there are substantial individual differences in cognitive competence.

The idea that cultural variation might be a serious challenge to some philosophical views or methods played a central role in the birth of experimental philosophy. In what is arguably the first article in experimental philosophy, Weinberg et al. (2001) examined whether classic intuitions in epistemology, such as the Gettier case, vary across cultures. They summarize their findings as follows (451; more on their findings below):

While in some cases what we’ve been reporting are just the brute facts that intuitions in different groups differ, in other cases what we’ve found is considerably more interesting. The differences between Westerners (Ws) and East Asians (EAs) look to be both systematic and explainable. EAs and Ws appear to be sensitive to different features of the situation, different epistemic vectors, as we will call them. EAs are much more sensitive to communitarian factors, while Ws respond to more individualistic ones. Moreover, Nisbett and his colleagues have given us good reason to think that these kinds of differences can be traced to deep and important differences in EA and W cognition.

The recent debate about cultural variation and philosophy has taken place on two fronts. First, there is a philosophical issue: Does cultural variation in philosophical intuition (if it is a fact) matter for philosophy (for opposite answers, see, e.g., Deutsch 2015; Machery 2017)? And is cultural variation a fact? Recently, the discussion of this second question has taken place among experimental philosophers (see Knobe 2019 and the exchange between Knobe on the one hand, and Stich and Machery on the other in this special issue). The Geography of Philosophy Project, led by Edouard Machery, Steve Stich, and Clark Barrett from 2017 to 2023, aimed at answering this question (Kiper et al. 2022).Footnote 1

This special issue brings together sixteen papers from psychologists, anthropologists, cultural evolution theorists, and philosophers to reflect on the extent, nature, and philosophical significance of cultural variation. Some of these papers reflect, sometimes critically, on the revolution started by “The weirdest people in the world?”; other papers focus on the existence and philosophical significance of variation in philosophical intuition; some papers are theoretical, others empirical, extending our knowledge of cultural variation or lack thereof. They all show how far we have gone in recent years and how much remains to be done.

In the remainder of this introduction, we briefly introduce the articles published in this special issue of the Review of Philosophy and Psychology. A first group of articles examines the idea that culture has a dramatic impact on cognition, perception, and philosophical intuition; a second group focuses on methodological questions: in particular, how to study cognition across cultures; a third group of articles presents empirical evidence relevant to assessing the extent to which the mind varies across cultures. We present each group in turn.

2 The Impact of Culture on Cognition

In “A Cultural Species and its Cognitive Phenotypes: Implications for Philosophy,” Joe Henrich, Damián Blasi, Cameron Curtin, Helen Davis, Ze Hong, Dan Kelly, and Ivan Kroupin review the large literature in cultural psychology, behavioral economics, anthropology, and linguistics showing that culture influences much of perception and cognition. On this basis, Henrich and colleagues argue that human beings have evolved cognitive mechanisms that adapt cognition and perception to their cultural environments: Homo sapiens is a cultural species. Finally, they discuss the implications of this view for the use of intuitions in theorizing, including in philosophy.

Continuing the themes of Henrich et al.’s article, Dominic Lopes and Madeleine Ransom’s “Perception in Practice” explores the impact of culture on aesthetic judgments. At least initially, one might think that this impact would involve two completely distinct processes. On one hand, there is an impact of social norms on higher-level cognition (analogous to what one finds in studies of economic decision-making); on the other, there is an impact of the physical environment on perception (analogous to what one finds in studies of perceptual illusions). Lopes and Ransom develop a new view that calls this dichotomy into question and makes it possible to see how the two processes could be more closely related than they might initially appear.

The significance of cultural variation for philosophy is the background of the next pair of papers.

In a noted paper, Knobe (2019) has claimed that, to a “shocking degree,” experimental philosophy has shown that “demographic factors do not impact people’s philosophical intuitions,” and that this is “an important finding that promises to have profound implications for metaphilosophical questions.” In support of this claim Knobe cited “30 studies, by 91 different researchers, comprising a total sample size of 12,696 participants.” In “Demographic Differences in Philosophical Intuition: a Reply to Joshua Knobe,” Stephen Stich and Edouard Machery contend that Knobe has cherry-picked the studies he cites. They cite 100 studies by 205 researchers with a total sample size of over 40 million participants, each of which reports demographic differences in philosophical intuitions. Stich and Machery go on to argue that the metaphilosophical implications of some of the studies Knobe cites are quite different from the implications Knobe proposes. These studies show that the philosophical intuitions of professional philosophers differ from those of non-philosophers, and that, as Starmans and Friedman suggest, “the study of philosophy … results in a sort of echo chamber of intuitions disconnected from how concepts are used by others”. Knobe notes that several studies cited in two provocative papers by Stich and colleagues failed to replicate. Stich and Machery point out that we don’t know whether the 30 studies Knobe cites are replicable since there are no published attempts to replicate any of them.

In “Difference and Robustness in the Patterns of Philosophical Intuition Across Demographic Groups,” Joshua Knobe replies to Stich and Machery’s critique, defending his claim that philosophical intuitions are surprisingly robust across demographic differences. At the core of the response is the idea that a study can provide evidence for the claim that philosophical intuitions are surprisingly similar across demographic groups even if it does find some statistically significant differences between those groups. Knobe pursues this strategy by looking in more detail at some of the studies cited within Stich and Machery’s critique. He argues that although those studies do find statistically significant differences between demographic groups, the main finding coming out of them is actually the surprising degree to which people have similar intuitions across demographic groups.

The last two papers in our first group examine two philosophical issues central to the view that culture and human cognition are deeply intertwined: the existence of different explanatory models of the influence of culture and cognition and the concerns about the adequacy of the notion of culture.

Armin Schulz’s “Explaining Human Diversity: The Need to Balance Fit and Complexity” focuses on two strategies for explaining human cognitive and behavioral diversity. One strategy appeals to fundamental differences, the other appeals to evoked differences. The contrast emerges clearly in debates over the explanation of sharing behavior. Henrich and colleagues have shown that there are striking cultural differences in ultimatum game decisions. The median offer among the Hadza is about 25%, while among the Sursurunga it is over 50% and lower offers are frequently rejected. A fundamental strategy for explaining the difference maintains that the psychological mechanisms underlying sharing dispositions are learned from the cultural environment. These mechanisms are fundamentally different. An evoked explanation maintains that all humans have the same sharing psychology -- the amount shared is determined by the coefficient of relatedness. The differences between cultures are traced to different cultural strategies that may be available to estimate degree of relatedness. Shultz argues that in deciding between these explanations we need to do more than determine which theory best fits the data. We must also consider which theory is more complex and whether a theory fits the data sufficiently better to make up for its increased complexity.

Andrew Buskell’s “Demographic Cultures and Demographic Skepticism” focuses on skeptical arguments aimed at the practice of appealing to the concepts of culture and cultural groups to explain behavioral differences. He focuses on four problems posed by the skeptics who maintain that the problematic explanations: (i) are committed to assumptions of a “folk anthropological” model that takes cultural groups to have essential properties, to be holistically organized, homogeneous with respect to values, practices, and beliefs, and have strong boundaries that prevent hybridization and diffusion of culture; (ii) are committed to a “hidden structure” version of essentialism; (iii) lack clear ontological operationalizations for “culture” and “cultural groups”; (iv) do not identify causal mechanisms that explain the systematic similarities and differences between cultural groups and their members. Buskell argues that each of these problems can be, and has been, avoided in a number of important empirical and theoretical studies. He also proposes four recommendations for how comparative social scientific research should be undertaken. The work should: (i) avoid or justify assumptions of the folk anthropological model; (ii) adopt the metaphysical framework of relational essentialism; (iii) explicitly articulate ontological operationalizations for “culture” and “cultural groups”; (iv) link empirical claims about cultural groups to causal mechanisms that can explain systematic similarities and differences.

3 Methodological Questions

We now turn to the second group of articles, focused on methodological questions. The first three papers consider the challenges raised by cross-cultural research as well as its importance.

Carles Salazar’s “The Cross-Cultural Study of Mind and Behaviour: A Word of Caution” calls attention to theoretical vulnerabilities that the cross-cultural study of mind and behavior might entail. He divides them into three categories: epistemological, ontological, and ethical. To illustrate his epistemological concerns, he focuses on work by Tanya Luhrmann and colleagues on cultural variation in models of the mind. Luhrmann and colleagues maintain that these differences explain why people in different groups are amenable to different sorts of religious beliefs. Salazar questions the explanatory value of Luhrmann’s findings and contrasts her findings with studies showing that our actual Theory of Mind mechanism is pan-human. To illustrate his ontological concerns, Salazar focuses on work by Bethany Ojalehto and her associates purporting to show that American college students and people in the Ngöbe indigenous community of Panama attribute agency in very different ways. As a result, the Ngöbe think that the sun and the ocean are alive. Though Ojalehto and colleagues contend that the Ngöbe ontology is on a par with our own, Salazar disagrees. To illustrate the ethical risks of cross-cultural research, Salazar recounts Richard Shweder’s work on female genital mutilation. Salazar argues that there is no straightforward argument from the widespread cultural acceptance of female genital mutilation to the moral acceptability of the practice.

In “The Challenges to the Study of Cultural Variation in Cognition,” Martin Packer and Michael Cole assemble a list of seven challenges to the sort of cross-cultural research that has been done by experimental philosophers. To illustrate these challenges, they focus on a well-known study of intuitions about free will by Sarkissian and colleagues (2010). The title of that study was “Is Belief in Free Will a Cultural Universal?” and the tentative answer defended was yes. The challenges that Packer and Cole explore include how culture is to be defined, how to find representative samples when making claims about a culture, and how to characterize and empirically investigate the sorts of “intuitive” cognitive processes that are of interest to many experimental philosophers. Explaining the task to participants poses a particularly important problem since the terminology used may be interpreted differently by different participants. For example, Sarkissian et al. ask participants whether characters in their vignettes are “fully morally responsible,” which might be interpreted differently in different cultures. Sarkissian et al. conclude that “individuals everywhere seem to embrace indeterminism and incompatibilism,” but Packer and Cole challenge this interpretation of their results since the study considered only four groups of people and substantial minorities of the participants – from 15 to 35% – were determinists.

Taking the study of cross-cultural psychology in an importantly different direction, Anton Killin and Ross Pain turn to the field of what is called “cognitive archaeology” in “How WEIRD is Cognitive Archaeology? Engaging with the Challenge of Cultural Variation and Sample Diversity.” Work within this field is concerned not with the human beings who exist today but rather with ancient humans and with members of other, now-extinct hominin species. Research in cognitive archaeology takes evidence from the archaeological record, combines this evidence with broader theories from cognitive science, and aims thereby to arrive at conclusions about the cognition of ancient humans, Neanderthals, etc. But, ultimately, what are our reasons for accepting these broader cognitive theories in the first place? Killin and Pain argue that the theories are often derived from research on contemporary humans from a very limited range of cultures, and that this problem may endanger certain core inferences within existing cognitive archaeology research.

The next two papers in this second group of papers are prescriptive: They propose some rules or heuristics to conduct methodologically and ethically sound cross-cultural research.

In “Developing Cross-Cultural Data Infrastructures (CCDIs) for Research in Cognitive and Behavioral Sciences,” Oskar Burger, Lydia Chen, Alejandro Erut, Frankie Fong, Bruce Rawlings, and Cristine Legare take up questions about the infrastructures a team should use when conducting cross cultural research, which they call Cross- Cultural Data Infrastructures (CCDIs). Drawing on existing work using such infrastructures, the paper makes a number of detailed recommendations regarding best practices. One recommendation is that CCDIs should involve iterative rounds of piloting, adaptation, and validity checks, which would gradually hone materials for cross-cultural research. Another key recommendation is that the research team itself should include people from the cultures being studied. The paper explores in detail specific steps that can be taken to achieve these goals.

In “A roadmap to doing culturally grounded developmental science,” Tanya Broesch, Sheina Lew-Levy, Joscha Kärtner, Patricia Kanngiesser, and Michelle Kline explore the complex questions researchers face when they are conducting cross-cultural developmental studies. Throughout, they emphasize that there is no single “best practice,” and that different studies, conducted in different circumstances, might be best conducted by addressing these questions in quite different ways. For example, they emphasize that different cross-cultural studies have quite different research questions and should therefore be conducted in different ways. Importantly, Broesch et al. address a number of important questions for developmental research that would not arise for research on adults. As one example, they discuss the more practical or logistical obstacles that arise especially for cross-cultural studies on children.

4 Empirical Studies

The third group of papers presents new cross-cultural research and new research bearing on the variation or invariance of philosophical intuitions.

In “Ethnomedical Specialists and their Supernatural Theories of Disease,” Aaron Lightner, Cynthiann Heckelsmiller, and Ed Hagen examine the relation between ethnomedical knowledge and religious healing, first by studying ethnographic data in the Human Relations Area Files, second, by interviewing 84 Maasai pastoralists. Lightner and colleagues report that efficacy plays a central role in clients’ choice of ethnomedical specialists; what’s more, they report that ethnomedical knowledge is often intertwined with “religious” or “supernatural” concepts. In a fascinating explanation, Lightner and colleagues propose that the distinction and contrast between supernatural and natural concepts might not make sense in many cultural contexts.

A number of studies have explored the relationship between performance on the Cognitive Reflection Test (CRT) and philosophical judgments, and these studies find systematic relationships between people’s capacities for cognitive reflection and their responses on certain classic philosophical thought experiments. Pushing this line of research in a new direction, Nick Byrd’s “Great Minds Do Not Think Alike: Philosophers’ Views Predicted By Reflection, Education, Personality, And Other Demographic Differences” reports two new studies asking whether these correlations show up even among philosophers. The results indicate that there are indeed correlations between CRT scores and philosophical judgments even among philosophers. For example, philosophers who receive higher scores on the CRT (indicating a greater ability for cognitive reflection) are less likely to believe in god.

The last three papers of our third group are cross-cultural papers in experimental philosophy.

Chad Gonnerman, Banjit Singh, and Grant Toomey’s “Authentic and Apparent Evidence Gettier Cases Across American and Indian Nationalities” considers the distinction between so-called authentic- and apparent-evidence Gettier cases that was introduced by Starmans and Friedman (2012). Starmans and Friedman reported that while lay people tend not to assign knowledge in the latter type of cases, exactly as philosophers do, they surprisingly assign knowledge in the former. Gonnerman and colleagues’ findings suggest that the story is more complicated than presented by Starmans and Friedman: People do not appear to distinguish authentic- and apparent-evidence Gettier cases consistently, and Indians and Americans appear to differ sometimes, but not always, in their judgments in response to such cases.

In “Western Skeptic vs Indian Realist. Cross-Cultural Differences in Zebra Case Intuitions,” Krzysztof Sękowski, Adrian Ziółkowski, and Maciej Tarnowski replicate one of the earliest, most influential findings in experimental philosophy: Weinberg and colleagues’ (2001) finding that Indians are less likely to assign knowledge in the Zebra case than Americans. While several results reported by Weinberg et al. (2001) have not been successfully replicated (Seyedsayamdost 2015; Kim and Yuan 2015; Machery et al. 2017a, 2017b), Sękowski and colleagues successfully replicate this cultural difference. What’s more, they explain the cultural difference in knowledge ascription by appealing to culturally varying attitudes toward the trustworthiness of perception.

Finally, Louisa Reins, Alex Wiegmann, Olga Marchenko, and Irina Schumski’s “Lying Without Saying Something False? A Cross-Cultural Investigation of the Folk Concept of Lying in Russian and English Speakers” examines whether one can lie by suggesting something false, despite saying something that is literally true or rather whether lying requires saying something false. They found that Russians and British tend to agree about this question: It is possible to lie by making statements that are literally true, but that deceptively suggest something false. Thus, the folk concept of lying does not appear to vary between Russians and British, and, in contrast to what some philosophers hold, does not require saying something that one knows is false.