Evolutionary Behavioral Sciences © 2020 American Psychological Association ISSN: 2330-2925 2020, Vol. 14, No. 4, 316 –323 http://dx.doi.org/10.1037/ebs0000210 Evolutionary Psychology Is a Scientific Revolution David M. Buss This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. University of Texas at Austin Evolutionary psychology provides a cogent meta-theory for psychological science. Historical assumptions of prior meta-theories are fatally flawed and known to be empirically incorrect. Evolutionary psychology provides a sound scientific framework for understanding human nature— one that is consilient with known causal processes of all life forms, particularly natural and sexual selection. Empirical evidence continues to accumulate for the heuristic and predictive power of the evolutionary psychology meta-theory, supporting the case for a scientific revolution in psychology. Public Significance Statement Evolutionary psychology provides a cogent meta-theory for psychological science. Historical assumptions of prior meta-theories are fatally flawed and known to be empirically incorrect. Evolutionary psychology provides a sound scientific framework for understanding human nature— one that is consilient with known causal processes of all life forms, particularly natural and sexual selection. Empirical evidence continues to accumulate for the heuristic and predictive power of the evolutionary psychology meta-theory, supporting the case for a scientific revolution in psychology. Keywords: evolutionary psychology, scientific revolution, metatheory, sex differences tion, providing a fundamental paradigm shift and remains today the only cogent metatheory for understanding the complexities of the human mind and all of its multifaceted components. It is a framework that unifies psychology with the rest of the life sciences in what E. O. Wilson called consilience. To understand why evolutionary psychology truly is a scientific revolution, it is necessary to provide a brief history the discipline of psychological science. Many trace the field to 1879 when Wilhelm Wundt founded the first psychological laboratory in Germany. Since then, different schools of thought became popular and then faded—the embrace of phenomenology, the rejection of subjective experience, and the reign of behaviorism. Behaviorism provided the most dominant metatheory the field of psychology in the 20th century until cognitive psychology and then evolutionary psychology came along. Behaviorism viewed humans as fundamentally subject to precisely the same laws of Most scientists live their lives never experiencing a scientific revolution within their discipline—a seismic theoretical shift, a new paradigm that fundamentally alters how scientists view their subject matter. Astronomers experienced it during the Copernican revolution in the 1500s, which displaced the earth as the stationary center of the universe. Biologists did after 1859, when Darwin’s On the Origin of Species unified all species into one grand tree of descent and furnished the fundamental causal process by which new species and their component adaptations are formed. As a psychologist, it is an extraordinary gift to be living and working within another rare scientific revolution. Evolutionary psychology truly is a scientific revolu- This article was published Online First May 14, 2020. Correspondence concerning this article should be addressed to David M. Buss, Department of Psychology, University of Texas at Austin, 108 East Dean Keeton, A8000, Austin, TX 78712. E-mail: dbuss@austin.utexas.edu 316 This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. EVOLUTIONARY PSYCHOLOGY IS A SCIENTIFIC REVOLUTION learning as all other organisms— classical Pavlovian conditioning and Skinnerian operant conditioning. This pan-species fundamental metatheoretical assumption explains why Skinner was able to title his 1938 treatise The Behavior of Organisms, a grandiose appellation, and why rats and pigeons could stand in as test subjects for humans. The metatheoretical assumptions of behaviorism were explicit. Humans and other organisms came into the world equipped with a very small number of extremely domain-general learning mechanisms and a small number of primary reinforcers, food being the most important. Adult behavioral repertoires were solely the products of a developmental history of paired associations (e.g., a bell with food) and reinforcement contingencies (e.g., pellets after regimented forms of pecking a disk). Behaviorism contained the premise that it was unscientific to posit processes occurring within the head. External reinforcement contingencies during each individual’s lifetime provided the exclusive causal explanations for manifest behavior, from pigeon pecking to adult mating behavior, and overtly expressed behavior was the only proper target for scientific study. The mind was both a blank slate on which the learning contingencies wrote the scripts and a black box that contained nothing of scientific interest or explanatory power. These metatheoretical assumptions began to crumble in the 1960s with the work of John Garcia and others who documented behavior that violated what were presumed to be the fundamental laws of learning. Rats could learn in a single trial to avoid foods that made them nauseous 24 hr later but could not learn after hundreds of trials other paired associations such as light flashes with nausea. In 1971, Seligman introduced the notion that biological preparedness, the idea that people come into the world equipped to form some specific associations between stimuli and responses very easily and other associations only with tremendous difficulty. In 1977, Richard Herrnstein, a former student of Skinner, published an article titled “The Evolution of Behaviorism,” in which he argued that humans had many drives, not few, and that primary reinforcers such as food and sex operated according to different principles (Herrnstein, 1977). Food consumption, he ar- 317 gued, differs fundamentally from sexual consummation. And with the cognitive revolution in the 1960s and 1970s, it became not just scientifically respectable to look inside the minds of humans, it became absolutely essential. Unfortunately, the cognitive revolution carried over from behaviorism the core assumption of domain generality. Instead of domain-general learning processes applicable to all areas of human behavior, cognitivists posited domaingeneral information processes. Just as behaviorism posited no specialized learning mechanisms that might differ, say, from incest avoidance learning to food aversion learning, cognitivists posited no specialized information processing mechanisms. Just as you can program a computer to perform thousands of very different tasks, cognitivists assumed that domain-general information processers could generate thousands of different behaviors. The domaingeneral cognitive metatheory also failed to provide something critical to human behavior—an explanation of the specific sorts of information humans and other organisms are designed to process. Evolutionary psychology furnished the conceptual tools for filling this key gap. Evolutionary psychology overturned problematic assumptions of prior metatheories and furnished radically different, but required, pieces of the explanatory puzzle. First, it viewed evolutionary processes not merely as optional, to be brought in only when all other causal forces failed to explain, but rather as essential for predicting and explaining human thoughts and behaviors. Second, evolutionary psychology conceives of the mind as containing a large number of specialized psychological mechanisms, each tailored to solving fundamentally different adaptive problems, in addition to whatever somewhat more domain-general mechanisms it contains. Third, identifying the adaptive functions of psychological mechanisms became indispensable—ascertaining the specific ways in which each mechanism historically led to an outcome tributary to reproductive fitness. Fourth, it dissolved the antiquated, yet still stubbornly persistent, dichotomies such as nature versus nurture and biological versus cultural and innate versus learned within a unified theoretical framework. An example illustrates these four revolutionary contributions. We now know that hu- This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. 318 BUSS mans have evolved incest-avoidances adaptations, but people do not come into the world knowing who their genetic relatives are; this information must be learned. Humans come into the world with food aversion–learning mechanisms, learning in a single trial to avoid eating food that makes them sick as much as 24 hr later, but food-learning adaptations do nothing for learning which people to avoid mating with. People do not come into the world knowing what leads to high or low status within a social hierarchy but must learn those criteria based on information provided by other people through language, social reputation, and observation of the attention structure (high-status people tend to be those to whom the most people pay the most attention). These learning examples illustrate some of the key contributions of evolutionary psychology and clarify why neither the behaviorist nor the mainstream cognitivist paradigms can do the explanatory job. First, evolution by selection is required for explaining why these different specialized learning adaptations exist at all—they evolved to solve distinct adaptive problems. Second, it highlights why the mind contains many, not just a few, adaptive information processing mechanisms. Problems such as incest avoidance, food consumption, and negotiating status hierarchies cannot be solved with one general learning mechanism. Successful solutions to one problem such as food selection (e.g., cues to nutrientrich and nontoxic consumption items) differ from successful solutions to other problems such as mate selection (e.g., cues to fertility) or habitat selection (e.g., cues to resource-rich environments that contain places to see without being seen—prospects and refuge). Third, understanding the adaptive function of each mechanism—the specific manner in which it contributed to survival and reproduction—is an indispensable, not an optional, endeavor. These three revolutionary shifts were entirely absent from psychological paradigms prior to evolutionary psychology. Fourth, the examples of evolved learning adaptations illustrates why dichotomies such as learned versus innate are indeed false. Humans have evolved specialized learning mechanisms, without which particular forms of learning cannot occur. Experiencing co- residence during development, for example, appears to be required for providing cues to genetic relatives, which is necessary for incest avoidance learning (Lieberman, Tooby, & Cosmides, 2003). So asking whether incest avoidance is learned or innate is conceptually incoherent. Evolutionary psychology dissolves the false dichotomies with a formulation of evolved psychological mechanisms as specialized information processing circuits that require input from the social, physical, or internal environments; procedures inside the head that process that input; and output in the form of manifest behavior aimed toward solving specific adaptive problems. A Personal Journey to a Scientific Revolution of Evolutionary Psychology I first encountered evolutionary theory in a geology class and cosmological evolution in an astronomy as an undergraduate. What fascinated me was that there existed theories to explain the origins of things—the origin and evolution of the universe, the origins and evolution of life on earth. Perhaps this had been obvious to everyone else, but it was a revelation for me. After considering majors in astronomy and geology, I settled on psychology. As fascinating as stellar evolution and plate tectonics were, the human mind fascinated me more. I wanted to understand what made people tick. I wanted to understand what motivated them to get out of bed in the morning and pursue the tasks toward which they channeled their energy. In short, I wanted to understand human nature. As a psychology major, acquiring the body of knowledge in psychology proved informative. The field had documented many fascinating findings—the tendency of people to socially loaf or slack off in their efforts as a function of the number of people working on a task; the proclivity of people to experience a degree of self-confidence that overestimated their actual performance; cognitive biases that seemed to violate the rules of formal logic; the demonstration that people became more cruel toward others when cloaked in anonymity; and many others. Despite the profusion of interesting findings and effects, the field lacked entirely an explanation for the origins of these phenomena. Strangely, most psychol- This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. EVOLUTIONARY PSYCHOLOGY IS A SCIENTIFIC REVOLUTION ogists reveled in the findings but did not seem to be interested in why they existed. Why would the mind be designed to slack off when performing group tasks or to overestimate their task performance? Moreover, psychology lacked a metatheory that could render the field coherent and unified, rather than a motley collection of interesting, but scattered, effects; a metatheory that rendered coherent including studies of vision and audition within the covers of the same introductory book that contained studies of cooperation and warfare. The subfield of personality psychology seemed at first to offer what I was looking for. It contained grand theories of human nature— Freud’s theory of instincts and intrapsychic mechanisms, Maslow’s theory of a hierarchy of needs and self-actualization, Adler’s theory of striving to overcome feelings of inferiority, and many others. Upon studying these theories, all struck me as containing some elements that resonated intuitively. But they all seemed arbitrary, lacking a foundational set of principles by which one could adjudicate among them. My graduate training in personality psychology did little to answer my questions, and indeed it furthered my doubts. One of my mentors, Dr. Jeanne Block, wrote papers on the origins of sex differences. She espoused the view that boys and girls did differ, but they started out identical in their psychology. Parental and cultural socialization provided the sole explanations. Parents dress their girls in pink and their boys in blue. They give girls Barbie Dolls and boys balls, bats, and trucks. Teachers rewarded girls for being submissive and obedient but rewarded boys for being aggressive and independent. The crowning achievement of Jeanne Block’s career was a science documentary that she helped script, aptly titled “The Pinks and the Blues,” in which she was featured on camera articulating her explanations for sex differences. Unstated and unclear were answers to the key question of why parents would be motivated to treat girls and boys so differently. Nor was it clear why girls and boys would be passive receptacles of parental socialization practices. Nor was it clear that the direction of effects was one directional from parents to children. Could children be influencing their par- 319 ents in which toys they found interesting or boring? While being exposed to my mentor’s teachings in the mid- to late 1970s, I started reading evolutionary biology in my spare time. My most important discovery was sexual selection theory, which I first encountered in a used book I purchased, an edited volume published in 1972 commemorating the 100th anniversary of Darwin’s 1871 theory. I discovered that sex differences existed in many species, not just humans, and sexual selection theory provided a cogent and nonarbitrary explanation for their origins. The field of psychology, I realized, had no knowledge of sexual selection theory. Nor did psychology understand other powerful theories within evolutionary biology such as the theory of parent-offspring conflict, the theory of reciprocal altruism, sexual conflict theory, and the theory of inclusive fitness. Not a single graduate program in psychology required as much as a single course in evolutionary biology to obtain a PhD. Consequently, the entire field of psychology ignored a unifying framework that could provide a nonarbitrary foundation for a theory of human nature and the causal processes from which human nature originated. Despite my fascination with evolutionary theory and its potential applicability to the human mind and behavior, my mentors proved indifferent to my interest. They tolerated my preoccupation with evolutionary biology with mild amusement but did not see its importance. So I devoted much of my graduate student effort to publishing a handful of articles in more mainstream personality psychology, enough to land a job as assistant professor at Harvard University. Once there, I felt free to study whatever I wanted with no mentors looking over my shoulder. I hit upon the idea to test predictions from Trivers’ (1972) theory of parental investment and sexual selection, George C. Williams’ (1975) predictions regarding the importance of age and reproductive value, and Donald Symons’ (1979) evolution-based theories of human sexuality. It started as a side project more for my own curiosity rather than as my primary research focus. But once the empirical results started to roll in that supported evolution-based predictions, I felt for the first time that I was on to This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. 320 BUSS something scientifically important. While at Harvard, I sought out other evolutionists who might share my interest. I sat in on lectures by Steven J. Gould; I met with E. O. Wilson, who kindly gave me a tour of his ant laboratory; I attended Irv DeVore’s simian seminar; I met Martin Daly and Margo Wilson, who spent a sabbatical at Harvard and whose classic book, Sex, Evolution, and Behavior, proved influential in my thinking; and importantly, I met Leda Cosmides and John Tooby. They were graduate students at Harvard, she in psychology and he in bioanthropology. At that point in the early 1980s, they had published only one article— on cytoplasmic inheritance— but had not yet published anything on evolutionary psychology. The field of evolutionary psychology simply did not exist. After 4 years at Harvard, a key opportunity came my way—the University of Michigan offered me a tenured position as associate professor in 1985. With the job security that tenure provided, I was totally free to begin publishing what I suspected would be controversial work—sex differences in human mate preferences, tested in 37 cultures, predicted in advance by evolution-based hypotheses (Buss, 1989b). This work cascaded into a florescence of research projects that proved the first of their kind—the first studies of human mate-retention tactics (Buss, 1988a), tactics of attraction (Buss, 1988b), derogation of competitors (Buss & Dedden, 1990), mate-poaching tactics (Schmitt & Buss, 2001), conflict between the sexes (Buss, 1989a), sex differences in jealousy (Buss, Larsen, Westen, & Semmelroth, 1992), and others. Simultaneously, Leda Cosmides and John Tooby began to publish their seminal works— developing the conceptual foundations of evolutionary psychology by integrating principles of evolutionary biology with cognitive principles of adaptations as information-processing devices, and illustrating those foundations with a program of experimental work on social contract theory, with special attention to a hypothesized cheater-detection mechanism (e.g., Cosmides, 1989; Cosmides & Tooby, 1987, 1992; Tooby & Cosmides, 1990, 1992). Their theoretical work on the conceptual foundations had a profound influence on my thinking. They integrated the notion of the mind as a collection of information processing circuits with the edifice of evolutionary theory. I realized that my work on human-mating psychology was just one example of a broader scientific revolution in the making. The Big Question: When Will the Field Accept Evolutionary Psychology as a Metatheory? In my experience, the hard hand of empirical studies, from observations to experiments, compels psychologists more than conceptual arguments. Research on human mating psychology turned out to be a pivotal success story within this new science of the mind. Psychologists are trained to be empirical scientists first and foremost. They tend to be convinced by data and findings. Some of my psychology colleagues view any theory with great skepticism, and some see no need for theory at all. The large empirical body of findings about human mating, combined with groundbreaking work by Cosmides and Tooby on social contract theory and similarly groundbreaking work on social conflict within families by Martin Daly and Margo Wilson, however, proved impossible to ignore. Since those early days, impressive scientific knowledge has accrued around the behavioral immune system, the evolution of emotions ranging from envy to sexual disgust, the evolution of cooperation, the evolution of aggression, kin psychology, and many others. The empirical edifice has expanded dramatically over the past three decades and continues to grow stronger every month. In each domain of study, with each empirical success, evolutionary psychology became impossible to ignore. Like all scientific revolutions, evolutionary psychology experienced, and continues to experience, vigorous opposition. Some attacked specific empirical findings. Some argued that the findings could be explained with nonevolutionary accounts. Regarding my own work, some proposed, after the findings had been published, that sex differences in mate preferences, for example, could be explained by social role theory, whereby men and women were assigned different roles by society, with men assigned the bread-winning role and women assigned the nurturing role. Precisely This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. EVOLUTIONARY PSYCHOLOGY IS A SCIENTIFIC REVOLUTION who was doing the assigning was never made clear. Nor was it clear why women and men would passively adopt whatever roles they were assigned. Nor could social role theory explain why men valued physical attractiveness more than women, why men preferred younger mates and women older mates, or why standards of female attractiveness corresponded so closely to cues of fertility and standards of male attractiveness corresponded more closely to cues to social status and protective prowess. Despite these explanatory gaps, social role theory could be applauded for generating one very specific prediction: As cultures become more gender egalitarian, sex differences should shrink. This pivotal prediction now has been overwhelmingly refuted. Several massive crosscultural studies, conducted by different teams of researchers, show the counterintuitive finding that psychological sex differences tend to get larger in gender egalitarian cultures, not smaller (e.g., Schmitt et al., 2017; Lippa, 2010; Walter et al., 2020). Despite these refutations, many mainstream psychologists cling to social role theory and reject the evolutionary hypotheses that predicted the sex differences well in advance of the empirical tests. In addition to attacks on specific empirical findings discovered by evolutionary psychologists, which of course are fair game and good for scientific progress, others have attacked the conceptual foundations of the evolutionary psychology metatheory. A nontrivial number of these attacks are based on outright misunderstandings of the logic of evolutionary theory itself; recall that psychologists receive no training in evolutionary biology, so it is perhaps not surprising that most do not understand it. These misunderstandings have been repeatedly pointed out elsewhere (e.g., Al-Shawaf, Zreik, & Buss, 2018; Confer et al., 2010; Lewis, AlShawaf, Conroy-Beam, Asao, & Buss, 2017; Park, 2007; Winegard, Winegard, & Deaner, 2014). Misunderstandings about evolutionary psychology include: (a) confusions about ultimate versus proximate explanation; (b) the false accusation of genetic determinism; (c) adhering to antiquated dichotomies such as nature versus nurture; (d) misconstruals about the logic of the concept of the environment of evolutionary 321 adaptedness (it is not a time or place, as some believe, but rather a statistical aggregate of selection pressures specific to each adaptation); (e) the false claim that evolutionary psychological hypotheses are unfalsifiable (e.g., several have been falsified already; see Confer et al., 2010); and others. Many critics do not seem motivated to conduct enough proper scholarship to accurately depict a metatheory they seem highly motivated to reject. It has become apparent that some of the motivated rejection is based on ideology (e.g., Buss & von Hippel, 2018; Von Hippel & Buss, 2017). I have argued that humans have not evolved to be dispassionate scientists. Our evolved psychology, including tribal coalitionary psychology, motivated reasoning, and intuitive theories of mind, ironically, interfere with our ability to understand our evolved psychology. Some attacks on evolutionary psychology, however, are based in legitimate scientific disagreements. Perhaps the most important is the claim that domain-general processes, not specialized adaptations, can adequately human behavior (e.g., Heyes, 2018). This goes to the heart of the evolutionary psychology metatheory. If evolution by selection has indeed created solely domain-general mechanisms, either of the sort posited by behaviorists, associationists, or cognitivists, then science could simply acknowledge this fact and then proceed to ignore evolutionary theory. It is only if evolution by selection has created more specialized psychological adaptations whose adaptive functions are to solve particular survival and reproductive challenges and not others that the evolutionary psychology metatheory becomes compelling. There is room, of course, for legitimate scientific disagreement, and some adaptations are indeed somewhat more domain general than others. In my view, though, enough evidence has cumulated in the domains of mating psychology; sexual attraction; cooperation; kin altruism; the emotions of love, anger, disgust, shame, pride, and envy; and evolved standards of morality—findings that domain-general accounts neither predict nor explain—that the evolutionary psychology metatheory has borne out its empirical promise. As this empirical mountain of evidence continues to accumulate, it is my hope that psychologists will embrace 322 BUSS the revolutionary paradigm shift provided by evolutionary psychology. This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. References Al-Shawaf, L., Zreik, K., & Buss, D. M. (2018). Thirteen misunderstandings about natural selection. In T. Shackelford & V. Weekes-Shackelford (Eds.), Encyclopedia of Evolutionary Psychological Science (pp. 1–14). Cham, Switzerland: Springer Cham. http://dx.doi.org/10.1007/978-3319-16999-6_2158-1 Buss, D. M. (1988a). From vigilance to violence: Tactics of mate retention in American undergraduates. Ethology and Sociobiology, 9, 291–317. http://dx.doi.org/10.1016/0162-3095(88)90010-6 Buss, D. M. (1988b). The evolution of human intrasexual competition: Tactics of mate attraction. Journal of Personality and Social Psychology, 54, 616– 628. http://dx.doi.org/10.1037/0022-3514.54 .4.616 Buss, D. M. (1989a). Conflict between the sexes: Strategic interference and the evocation of anger and upset. Journal of Personality and Social Psychology, 56, 735–747. http://dx.doi.org/10.1037/ 0022-3514.56.5.735 Buss, D. M. (1989b). Sex differences in human mate preferences: Evolutionary hypotheses tested in 37 cultures. Behavioral and Brain Sciences, 12, 1–14. http://dx.doi.org/10.1017/S0140525X00023992 Buss, D. M., & Dedden, L. A. (1990). Derogation of competitors. Journal of Social and Personal Relationships, 7, 395– 422. http://dx.doi.org/10.1177/ 0265407590073006 Buss, D. M., Larsen, R. J., Westen, D., & Semmelroth, J. (1992). Sex differences in jealousy: Evolution, physiology, and psychology. Psychological Science, 3, 251–256. http://dx.doi.org/10.1111/j .1467-9280.1992.tb00038.x Buss, D. M., & von Hippel, W. (2018). Psychological barriers to evolutionary psychology: Ideological bias and coalitional adaptations. 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Do ideologically driven scientific agendas impede the understanding and acceptance of evolutionary principles in social psychology? In J. T. Crawford & L. Jussim (Eds.), Politics of Social Psychology (pp. 17–35). New York, NY: Psychology Press. http:// dx.doi.org/10.4324/9781315112619-2 323 Walter, K. V., Conroy-Beam, D., Buss, D. M., Asao, K., Sorokowska, A., Sorokowski, P., . . . Zupančič, M. (2020). Sex differences in mate preferences cross 45 countries: A large-scale replication. Psychological Science, 956797620904154. Williams, G. C. (1975). Sex and evolution (No. 8). Princeton, NJ: Princeton University Press. Winegard, B. M., Winegard, B. M., & Deaner, R. O. (2014). Misrepresentations of evolutionary psychology in sex and gender textbooks. Evolutionary Psychology, 12, 474–508. http://dx.doi.org/10 .1177/147470491401200301 Received March 18, 2020 Accepted April 3, 2020 䡲 Where Is Psychology Going? Structural Fault Lines Revealed by Psychologists’ Use of Kuhn Erin Driver-Linn Harvard University Psychologists’ appropriation of language and ideas from Thomas Kuhn’s (1962, 1970b) The Structure of Scientific Revolutions reveals deep and contradictory concerns about truth, science, and the progress of the field. The author argues that psychologists, uncomfortably straddling natural and social science traditions, reference Structure for 2 reasons largely overlooked: first, because it presents an intermediate, naturalistic position in the war between relativist and rationalist views of scientific truth, and second, because it presents a psychologized model of scientific change. The author suggests that the history of this mutual influence—psychologists being influenced by Kuhn and vice versa—may usefully inform current practices of psychological science. The human understanding is no dry light, but receives an infusion from the will and affections; whence proceed sciences which may be called “sciences as one would.” —Francis Bacon, Novum Organum T homas Kuhn’s (1962, 1970b) The Structure of Scientific Revolutions has been referenced in psychology journals a great deal for a history and philosophy of science text— on average, about 55 times per year (Coleman & Salamon, 1988, and see below). Accordingly, gadflies have argued that there has been “all too much idle chatter in loose Kuhnian terms about psychology” (Warren, 1972, p. 1196). Suppe (1984), for example, wrote that as chairperson of one of the major history and philosophy of science programs in the country, he ought to be overjoyed with the spate of publications from a Kuhnian perspective. Instead, he believed the dogmatic, ill-informed, and uncritical use of Kuhn to be distressing and feared that it might result in “several decades in an orgy of unproductive scientific practice” (Suppe, 1984, p. 100). Similarly, Holland (1990) said there was a “paradigm plague,” despaired of prevention, and instead suggested a tongue-in-cheek inoculation—to “plunge into prolific use of the paradigm concept” until cured (pp. 24 –25). Why have psychologists gravitated to the language and ideas in Structure? What can be learned from psychologists’ pervasive Kuhn referencing? I suggest that the Kuhn chatter in psychology reflects earnestly held concerns about divisions in the field, divisions that have arisen because scientific psychology necessarily encompasses both natural and social science traditions, which represent competing positions on truth and progress. I argue that the April 2003 ● American Psychologist Copyright 2003 by the American Psychological Association, Inc. 0003-066X/03/$12.00 Vol. 58, No. 4, 269 –278 DOI: 10.1037/0003-066X.58.4.269 particular position on truth and the model of progress presented in Structure have in some ways bridged, and in other ways engendered, these divisions. Finally, I maintain that the mutually influential relationship between psychology and Kuhn’s text may provide perspective on some consequential norms of the field. Perceptions of a Splintered Discipline Geertz, an anthropologist, provided a lovely summary of what seems a typical view of psychology: Since it got truly launched as a discipline and a profession in the last half of the nineteenth century . . . the self-proclaimed “science of the mind” has not just been troubled with a proliferation of theories, methods, arguments, and techniques. That was only to be expected. It has also been driven in wildly different directions by wildly different notions as to what it is, as we say, “about”—what sort of knowledge, of what sort of reality, to what sort of end it is supposed to produce. From the outside, at least, it does not look like a single field, divided into schools and specialties in the usual way. It looks like an assortment of disparate and disconnected inquires classed together because they all make reference in some way or other to something or other called “mental functioning.” Dozens of characters in search of a play . . . . The wide swings between behaviorist, psychometric, cognitivist, depth psychological, topological, developmentalist, neurological, evolutionist, and culturalist conceptions of the subject have made being a psychologist an unsettled occupation, subject not only to fashion, as are all the human sciences, but to sudden and frequent reversals of course. Paradigms, wholly new ways of going about things, come along not by the century, but by the decade; sometimes, it almost seems, by the month. It takes either a preternaturally focused, dogmatical individual, who can shut out any ideas but his or her own, or a mercurial, hopelessly inquisitive one, who can keep dozens of them in play at once, to remain upright amidst this tumble of programs, promises, and proclamations. (Geertz, 2000, pp. 187–188) Editor’s note. Thomas H. Leahey served as action editor for this article. Author’s note. I am very grateful for helpful advice and information from Jerome Bruner, Peter Buck, Daniel Gilbert, Anne Harrington, Jay Hook, Ken Nakayama, Barbara Rosenkrantz, and Sheldon White. I am especially indebted to one nonanonymous reviewer, Rachel Rosner— whose work and clarity hugely shaped the final product and whose longsighted perspective lent me courage. Correspondence concerning this article should be addressed to Erin Driver-Linn, Department of Psychology, William James Hall, 33 Kirkland Street, Harvard University, Cambridge, MA 02138. E-mail: edl@ wjh.harvard.edu 269 Erin DriverLinn Perceptions of psychology as beleaguered by fractionation and uncertainty are almost ubiquitous (cf. Gruber & Gruber, 1996; Kelly, 1998). The crisis may be seen in psychologists’ need to publish or perish that reduces thinking before publishing (Salzinger, 1996), in a poor understanding of human life and of the relationship of the science to the world (Bakan, 1996), in a lack of literacy in evolutionary theory and genetics (Tobach, 1999), in the split between the scientific and professional branches (Sexton, 1990), or in the split between the academic and the humanistic orientations (Lincoln, 1994). It may be considered an identity crisis that could be solved by requiring all psychologists to be solidly trained in the neurosciences (Panksepp, 1990). It may be seen in the dysfunctional symptoms of the field (Mos, 1996). It may even be seen as unsolvable until an unscientific approach is taken— one that does not buy into the myths of the individual, mental illness, and development, which have made psychology a pseudoscientific hoax (Newman & Holzman, 1996). The crisis may be thought of as acute in American psychology (Sexton, 1990) and in social psychology (Ibanez, 1985; Pancer, 1997), as resolved in the West but unresolved in Russia (Radzikhovskii, 1991), or as a misperception debunked by an analysis of three leading Dutch journals of psychology (Spangenberg & Nijhuis, 1985). This perception of psychology as being in a state of crisis is not a new one. As Cahan and White (1992) reviewed, there is a long-standing schism between experimental, laboratory-based psychology and interpretive, meaning-based psychology. The problem is embodied in the quotation from Münsterberg that opens Cahan and White’s review: “Do we not deceive ourselves if we fancy that we can approach the study of mental states with the same naivete with which we can turn to the study of 270 minerals and plants” (Münsterberg, 1915, p. viii)? Psychologists study humans (or at least hope that the animals or computer models that they study reveal something interesting about humans), and humans studying humans is a social enterprise, inherently subjective and interpretive. Psychology may, then, unavoidably be a social science, wedded to social science methods. Yet humans and the products of humans are part of nature, and nature has been studied objectively, in laboratories, to replicable, useful ends. Psychology, then, can operate within and may profitably gain from a natural science approach. It seems, though, that in practice, scientific psychologists want to understand phenomena. Usually, these phenomena can be best described using broad, descriptive labels—for example, memory, depression, emotion, learning, aggression, and consciousness—the kind that might be headings in introductory psychology textbooks. It seems clear that to understand such phenomena requires work at both natural and social, molecular and molar, levels of analysis. So, as an enterprise, to understand such phenomena, psychology looks for causal explanations with predictive power as well as meaningful, resonant interpretations of human behavior. Thus, psychology straddles two rooted traditions, the natural sciences and the social sciences. These traditions have long been separated from one another (Bunge & Ardila, 1987). Neither formal attempts to integrate psychology nor formal attempts to split psychology appear to have been enduringly successful (Cahan & White, 1992). It stands to reason that psychologists suffer from crises of identity. The divide is serious— each tradition carries different assumptions about what constitutes truth and, therefore, different assumptions about what constitutes progress. It turns out that Kuhn, in ways witting and unwitting, addressed this divide in Structure. Kuhn’s Middling Position on Truth The so-called science wars (Gross & Levitt, 1998; Rorty, 1999; Ross, 1996) are in essence disagreements about what constitutes good science. These disagreements are derived partly from the split between natural and social science traditions. In simplistic terms (other than that is beyond the scope of this article), the camps of the science wars include, on one side, a loosely banded group that includes objectivitists, rationalists, reductionists, positivists, and empiricists. This side maintains that scientific laws and truths can be gleaned through rigorous methods that winnow away the subjective from the objective, putting a premium on naturally occurring phenomena. On the other side is another loosely banded group of humanists, relativists, postmodernists, and social constructionists. This camp maintains that the premises of the other camp are faulty, that the objective cannot be winnowed away from the subjective. The rationalist camp assumes that the practice of science and, by extension, the products of science are not contaminated by external effects, whereas the relativists are almost defined by their challenge to that assumption. Skirmishes in this war have been waged and reviewed in several books April 2003 ● American Psychologist (e.g., Brante, Fuller, & Lynch, 1993; Cromer, 1997; Gross & Levitt, 1998; Hacking, 1999; Ross, 1996), by philosophers of science (e.g., Laudan, 1990), and doubtless in the cocktail chitchat of many a faculty club. It seems as if psychologists have internalized this war. They either pick a side (against their colleagues) or maintain half a belief in empirical results as sacrosanct and half a belief that science, like many products psychological, is, a construction. From this position of ambivalence, Kuhn’s philosophy of science is an appealing one to marshal—it is popular and catchy, and it strikes a balance in the war. How does it do this? The now famous and infamous argument in The Structure of Scientific Revolutions (Kuhn, 1962, 1970b) challenged a prevailing stance, and it was perhaps this, as well as the timing of the monograph, that gained Structure wild popularity (relative to other history and philosophy of science texts). To summarize, Kuhn claimed that sciences develop in identifiable stages: A budding science is somewhat disordered, made up of practitioners who do not share the same language or tenets (he termed such sciences pre-paradigmatic). It is only when these precepts coalesce, when practitioners move from factionalism to a shared viewpoint (making the science paradigmatic), that the science can make significant progress. Significant changes in viewpoint take place abruptly when something that has remained unexplained prompts a new point of view (a crisis in the science is resolved when an anomaly is identified and understood, thus initiating a revolution, a paradigm shift). The new point of view cannot be integrated with the old view (the two views are incommensurate). Furthermore, this new point of view does not represent advancement of knowledge (it does not presume accumulation of knowledge); it merely represents a new set of precepts. This last claim challenges the assumption that sciences move increasingly toward truth. Kuhn wrote, at the end of Structure, It is now time to notice that until the last very few pages the term “truth” had entered this essay only in a quotation from Francis Bacon. And even in those pages it entered only as a source for the scientist’s conviction that incompatible rules for doing science cannot coexist except during revolutions when the profession’s main task is to eliminate all sets but one. The developmental process described in this essay has been a process of evolution from primitive beginnings—a process whose successive stages are characterized by an increasingly detailed and refined understanding of nature. But nothing that has been or will be said makes it a process of evolution toward anything. Inevitably that lacuna will have disturbed many readers. We are all deeply accustomed to seeing science as the one enterprise that draws constantly nearer to some goal set by nature in advance. (Kuhn, 1970b, pp. 170 –171) Kuhn is often categorized as a thinker who looms large “in the conceptual universe of the relativist” (Laudan, 1990, p. xi). Kuhn, however, suggested that both rationality and relativism are implicated by the premise that the pursuit of science is bound to history, and he formally rejected the label of relativist in The Road Since Structure (Kuhn, 2000). It is worth rearticulating what he actually meant by truth because it is an odd, middling position in the science wars that readers may have picked up on but not quite understood. Kuhn (2000) said that the pivotal argument in Structure is one against “the correspondence theory of truth, the notion that the goal, when evaluating scientific laws or theories, is to determine whether or not they correspond to an external, mind-independent world” (p. 99). This argument is not a strong relativist position because a conception of truth is considered essential for scientists to make a “choice between acceptance and rejection of a statement or a theory in the face of evidence shared by all” (Kuhn, 2000, p. 99). Unlike a radical relativist or constructionist, Kuhn concluded that “underlying all these processes of differentiation and change, there must, of course, be something permanent, fixed, and stable” (Kuhn, 2000, p. 104). Kuhn’s (2000) self-described “interesting sort of relativism” (p. 307) might be more accurately termed naturalism (Mayo, 1996; Proctor & Capaldi, 2001). Naturalism is an approach to methods of inquiry that maintains that, in principle, no thing or event lies outside the reach of scientific explanation; it avoids appeals to a priori claims of any kind. Therefore, conclusions about the nature of science are subject to study and criticism. This suggests, then, that science produces “models of the world that may fit the world more or less well in something like the way maps fit the world more or less well” (Giere, 1999, p. 240). From this perspective, what is gained in science is not truth but working truths—very different from no truth. Naturalism (with Kuhn as its most well-known, but certainly not only, proponent) represents a particularly hopeful approach for psychologists to take when plagued by perceptions of crisis, caught between a natural science/ rationalist worldview and a social science/relativist worldview. This position suggests that maps, or models, or theories, or results can be empirically based, while acknowledging the subjectivity inherent in psychological inquiry. Results can fit the world in ways that are discernibly good or better than those of the past, without trying to make the shaky claim that psychological science is progressing toward perfect correspondence with a verifiable and objective reality. This is not to say that psychologists tend to cotton to Kuhn because they have it worked out that naturalism is a Kuhn’s claim that “scientific change does not consist in a relentless approach to a waiting truth but in the rollings and pitchings of disciplinary communities” was a “call to arms for those who saw science as the last bastion of epistemic privilege or a sin against reason for those who saw it as the royal road to the really real” (Geertz, 2000, p. 163).1 Thus, 1 As has been noted by Geertz (2000) and others, several theorists around the same time were also challenging cumulative and rational models of science (see, e.g., Hanson, 1958, 1970; Holton, 1964; Quine, 1953, 1969; Toulmin, 1961, 1972), but they have had far less impact in psychology. Thanks to Peter Buck and Ken Nakayama for pointing out these conceptual similarities and historical conjunctions. April 2003 ● American Psychologist 271 usefully bridging philosophy of science. Although Kuhn’s middling position on truth may have held an implicit appeal to many psychologists, it was his related model of progress that has held explicit appeal. As shown below, psychologists primarily reference Kuhn to make statements about progress— either the field’s status as a science or their own work described as signifying advancement. These statements signal ambivalence and insecurity—the marks of a field divided in approach and seeking some measure of progress. Kuhn’s Ambivalently Psychologized Model of Progress Although Kuhn’s position on truth may in some ways respond to divisions in psychology, his model of progress may have actually contributed to these divisions because he presented a mixed message in Structure about psychology. Kuhn used psychology as an example of a pre-paradigmatic science (to be compared with paradigmatic sciences such as physics)—that is, lower on a sort of growth chart. However, he also indirectly validated psychology as a science by using it as the basis of his model. Kuhn (1970a) stated that psychology and sociology were “weak reeds from which to weave a philosophy of science” (p. 235). Why? Because he formulated the ideas for Structure precisely because he noticed so much discussion about what constitutes a legitimate science among social scientists. He explained that before writing the monograph, he spent a year in “a community composed predominantly of social scientists” (Kuhn, 1970b, pp. vii– viii) and that this confronted me with unanticipated problems about the differences between such communities and those of the natural scientists among whom I had been trained . . . . I was struck by the number and extent of the overt disagreements between the social scientists about the nature of legitimate scientific problems and methods. (Kuhn, 1970b, p. viii) This comparison led him to suggest that before a field becomes paradigmatic, it is characterized by “frequent and deep debates over legitimate methods, problems, and standards of solutions, though these serve rather to define schools than to produce agreement” (Kuhn, 1970b, pp. 47– 48). He believed social scientists have a tendency “to defend their choice of a research problem . . . chiefly in terms of the social importance of achieving a solution” and asked, when compared with natural scientists, “Which group would one then expect to solve problems at a more rapid rate” (Kuhn, 1970b, p. 164)? However, Jerome Bruner, long a friend of Kuhn, wrote that Kuhn was not anti-psychology, only rather bored with psychologists generally who, on the whole, he thought were not serious about much other than playing safe . . . . If he had a specific complaint about the social sciences, it was not that they were not “advanced” but that they somehow lacked a sense of how they were going about their enterprises. (J. Bruner, personal communication, November 11, 1997, p. 1) 272 Kuhn himself diplomatically communicated to O’Donohue (1993) that in terms of its status as a science, “psychology is probably too much of a catchall field to generalize about” (p. 282)—perhaps because it includes elements of both natural and social sciences. Regardless, Kuhn used the output of this catchall field as the basis of his theory. The extent to which Kuhn deliberately built his theory around psychological theory seems to have gone largely unrecognized in the history and philosophy of science literatures. In Structure, Kuhn described change in science as a process of individual psychological development. He did so (a) by arguing that revolutionary change in science requires a gestalt switch and (b) by suggesting that scientific paradigms develop in normative, Piagetian-like stages. Kuhn was strongly challenged on these two points— both of which, he later acknowledged, resulted in much confusion— before the manuscript was published, as revealed in personal letters between Kuhn and his mentor, James Bryant Conant.2 The fact that Kuhn chose to push forward with these points in the face of such a challenge highlights the degree to which he felt they were important to his theory. Detailing the extent to which Kuhn deliberately presented a provocatively psychologized model of progress helps to explain the appeal Structure has to psychologists and the confusion that is reflected in their referencing of it. Gestalt Switches: The Problem of Using Individuals as a Stand-in for Groups Piaget’s (1929) theory of the assimilation and accommodation of anomalous information and the New Look work in perception together form the basis of Kuhn’s central tenet—that what scientists discover is limited by what they see. Kuhn (1970b) wrote in the preface to Structure that a “footnote encountered by chance” led him to Piaget’s experiments of children’s developmental transitions from one “world” to another and that he was struck by this work because it “displayed concepts and processes that also 2 On April 22, 1961, Kuhn sent Conant, then president of Harvard University, a draft of the Structure manuscript with a letter inviting criticism and making an appeal for Conant’s endorsement to a publisher. Conant replied in full on June 5th, outlining several extensive criticisms of the text. When Kuhn replied, he wrote that some of Conant’s comments “reflect fundamental disagreements; others reflect misunderstandings that have not arisen with other readers and whose source I cannot locate; a few I simply cannot understand” (T. S. Kuhn, letter to J. B. Conant, June 29, 1961, p. 1). Importantly, he said that to the extent that there were fundamental disagreements, he was not persuaded to make changes and that he was sure that Conant would feel displeased with the final manuscript, a fact which “will make me quite sad” (T. S. Kuhn, letter to J. B. Conant, June 29, 1961, p. 1). As can be gleaned from the published book and their correspondence, Kuhn did not substantively modify the final manuscript in concurrence with Conant’s views. The correspondence, however, did not end on a disagreeable note. There is a letter from Conant missing from the Archives (July 11, 1961) that was mentioned by Kuhn in a subsequent reply; Kuhn said that he was much appreciative of Conant’s “kind” letter, thanked him for “writing so nice a ‘period’ to the present exchange,” and asked to dedicate the book to him, saying, “you are the one who taught me that the turtle always travels fastest when his neck is out” (T. S. Kuhn, letter to J. B. Conant, August 5, 1961, p. 1). (The Kuhn–Conant letters are preserved in the Harvard Archives, UAI 15.898, Box 131, K Personal File in N.Y., Personal Letters.) April 2003 ● American Psychologist emerge directly from the history of science” (p. vi). He also told a group of child psychologists that since he had discovered history of science and Piaget, “the two have interacted closely in my mind and in my work. Part of what I know about how to ask questions of dead scientists has been learned by examining Piaget’s interrogations of living children” (Kuhn, 1977a, p. 21). Kuhn (1970b) said all scientific discoveries reveal a process of psychological transformation very akin to Piaget’s description of children’s assimilation and accommodation of concepts, namely, “the previous awareness of anomaly, the gradual and simultaneous emergence of both observational and conceptual recognition, and the consequent change of paradigm categories and procedures often accompanied by resistance” (p. 62; see also Kuhn’s [1973] essay in Henle, Jaynes, & Sullivan’s [1973] Historical Conceptions of Psychology). Kuhn described a Bruner and Postman (1949) experiment in Structure and wrote, “Either as a metaphor or because it reflects the nature of the mind, that psychological experiment provides a wonderfully simple and cogent schema for the process of scientific discovery” (Kuhn, 1970b, p. 64). Similarly, he used psychological studies to show how previously held paradigms form the basis of a worldview that can be completely transformed: An experimental subject who puts on goggles fitted with inverting lenses initially sees the entire world upside down . . . and the result is extreme disorientation, an acute personal crisis. But after the subject has begun to learn to deal with his new world, his entire visual field flips over . . . . Literally as well as metaphorically, the man accustomed to inverting lenses has undergone a revolutionary transformation of vision. (Kuhn, 1970b, p. 112) He concluded that Surveying the rich experimental literature from which these examples are drawn makes one suspect that something like a paradigm is prerequisite to perception itself. What a man sees depends both upon what he looks at and also what his previous visualconceptual experience has taught him to see. In the absence of such training there can only be, in William James’s phrase, “a blooming buzzin’ confusion.” (Kuhn, 1970b, p. 113) Conant, though, recommended eliminating Kuhn’s discussion of the perceptual process as unnecessary to the argument: I don’t think it is what people see—that matters. What matters is the guide to action which they accept. Passive seeing proves nothing. I don’t think “scientific perception” is a happy phrase . . . action is necessary. It is even in the psychological experiments which have so deeply impressed you. I think this whole section of your document complicates your fundamental argument. (J. B. Conant, letter to T. S. Kuhn, June 5, 1961, p. 3). Kuhn countered in his reply to Conant that what he was describing was not passive seeing; his argument is that there is no such thing as an objective point of view: Most of my argument is intended to indicate that there is no such thing, even as an ideal. It is just because my psychological experiments point in that direction—towards the role of what you April 2003 ● American Psychologist call guides to action—that I use them. (T. S. Kuhn, letter to J. B. Conant, June 29, 1961, p. 5) Kuhn maintained that he must include this portion of the argument because he found “it necessary to deny the existence of the process [objective perception] except as a possible construct from within a given world view” (T. S. Kuhn, letter to J. B. Conant, June 29, 1961, p. 6). Kuhn said, I would like you to see why the material is in there and also why I cannot view it as a mere complication in my fundamental argument. On the contrary, from my viewpoint the section on perception is the fundamental one in the monograph [italics added]. (T. S. Kuhn, letter to J. B. Conant, June 29, 1961, p. 6) Some of psychologists’ Kuhn referencing follows directly from this part of his argument. These psychologists see Kuhn’s statements about changes in sciences as informing how they think about the development of individuals. For example, Arca (1984) wrote that biological systems (in particular, the biological and cognitive development of children), like sciences, are characterized by periods of slow drift punctuated by revolutions: “There are apparently deep correspondences between the few basic strategies used in humans’ evolving scientific knowledge to interpret changes, and the few deep strategies which shape the explicit development of individuals’ thinking” (p. 339). Similarly, Andersen, Barker, and Chen (1996) argued that Kuhn’s account has been independently supported by recent research in cognitive psychology—in that changes in knowledge structures such as categories and exemplars occur in people the way that Kuhn, especially later in life, said they did in scientific structures. They also claimed that these “parallel accounts of concepts found in Kuhn and cognitive science lead to a new understanding of the nature of normal science, of the transition from normal science to crisis, and of scientific revolutions” (Chen, Anderson & Barker, 1998, p. 5). These psychologists and others (e.g., Gibson, 1984; Jiang, 1998; Khalidi, 1998) have, like Kuhn, found this sort of “ontogeny recapitulates phylogeny” notion a compelling one. Indeed, psychologists are not alone in finding Kuhn’s model of progress worthy of appropriation. Stephen J. Gould (1997), for example, suggested that something very like Kuhn’s theory underlies, and perhaps was part catalyst for, modern views of progress across scientific fields, that the incorporation and validation of the nonaccumulation view of change has had an immense impact on the practice of science generally. In fact, Gould stated that the ideas in Structure influenced the formulation of his own widely popular theory of punctuated equilibrium. However, Conant’s objection to this part of Kuhn’s argument was prescient. The leap from the individual to the group has been much criticized—and justly, as Kuhn himself noted with decades’ worth of hindsight: In Structure the argument repeatedly moves back and forth between generalizations about individuals and generalizations about groups, apparently taking for granted that the same concepts are applicable to both, that a group is somehow an individual writ 273 large . . . that use now seems to me mistaken. Groups do not have experiences except insofar as all their members do. And there are no experiences . . . that all the members of a scientific community must share in the course of a revolution . . . . In fact, like other visual experiences, gestalt switches happen to individuals, and there is ample evidence that some members of a scientific community have such experiences during a revolution. But in Structure the gestalt switch is repeatedly used also as a model for what happens to a group. (Kuhn, 1993, p. xiii) This leap is not just problematic logically. It contributes to a sense of confusion about how to assess progress. Paradigmatic Stages: The Problem of Mixing Description With Prescription Conant also found fault with Kuhn’s emphasis on the development of paradigms and paradigm shifts as key indicators of progress in a field. He first criticized the “use (and abuse) of a word you seem to have fallen in love with!” and “which is used so often in subsequent pages that [the reader] is ready to cry out in pain” (J. B. Conant, letter to T. S. Kuhn, June 5, 1961, pp. 1–2). On this point, Conant concluded, “I believe you dodge some of the difficulties of the detailed analysis of the application of your doctrines by taking refuge in the word ‘paradigm’” (J. B. Conant, letter to T. S. Kuhn, June 5, 1961, p. 3), and suggested replacing paradigm with theory. Conant also stated, “The difficulty with your treatment is that you focus attention on a few major scientific revolutions and by implications, at least, carry over to minor revolutions all that you say about the major ones” (J. B. Conant, letter to T. S. Kuhn, June 5, 1961, p. 2). He went on to say, “I like your distinction between an immature and mature science but I should not like to call the first period pre-paradigmatic” (J. B. Conant, letter to T. S. Kuhn, June 5, 1961, p. 2)! He pointed out that Kuhn’s terms and arguments ignored incremental advances, making identification of progress very difficult: “By leaving out any reference to technology and advances in the practical arts (including the practical art of experiment and observation) you distort the picture of science and get yourself into needless trouble about progress” (J. B. Conant, letter to T. S. Kuhn, June 5, 1961, p. 3). In his letter back to Conant, Kuhn said that he would clarify his use of the word paradigm but that he believed it was being used in a proper way (T. S. Kuhn, letter to J. B. Conant, June 29, 1961, p. 2).3 However, he maintained that his emphasis on revolutions, rather than incremental advances, was not at all “needless trouble about progress” because “progress is easy to define and evaluate only for a cumulative process,” and he disagreed that “cumulativeness is the distinguishing feature of science” (T. S. Kuhn, letter to J. B. Conant, June 29, 1961, p. 5). Kuhn has, then, overtly described scientific progress in terms of developmental stages—pre-paradigmatic, paradigmatic, crisis and revolution, and then a new paradigm (others have also described Kuhn’s model as a stage theory; e.g., Leahey, 1992, and Giere, 1999).4 Stages represent categorical designations. Conant seems to have been suggesting a continuum instead. Kuhn, by failing to give significance to minor changes that come from solutions to 274 practical problems and to acknowledge that a completely shared paradigm may not be a requisite for progress, created a dichotomy. In spite of the fact that he said these stages did not signify progress and in spite of the fact that he later clarified these points (see, e.g., Kuhn, 2000, p. 307), in Structure he is presenting a normative model, using characteristics of stages to signal a field as either paradigmatic or not, capable of revolutionary change or not. Whether he intended it to or not, highlighting stages generates hullabaloo. The designation of being at an earlier stage is pejorative; it is rarely preferable to be part of an enterprise that is immature, slow, pre-paradigmatic, or amorphous relative to others that are mature, advanced, paradigmatic, and cohesive. These are not just abstract concerns—the perception of a field as an evolving science, capable of generating solutions to well-articulated problems, yields very real resources, such as funding and interest on the part of bright students. Not surprisingly, then, the most substantive form of Kuhn referencing by psychologists is to use the ideas in Structure to size up the field, to figure out where psychology is and where it ought to be. The prototype for this form of usage is to describe the history of psychology in Kuhnian terms and then to assess the field’s current status as a science. The conclusions vary—some maintain that psychology is not a science, some that it is an immature science, and some that it is a bona fide paradigmatic science. This variance seems to come from practitioners being on different sides of the fault lines in the field, as well as from Kuhn’s reliance on psychology and the imprecision in the text that he later acknowledged. For example, Segal and Lachman (1972) argued that there was an identifiable paradigm in psychology between 1930 and 1960, “known variously as behavior theory, learning theory, neobehaviorism, or S-R psychology,” and that changes in this area are “changes in an established science rather than preparadigmatic variation” (p. 46), which led them to speculate that the field at the time of writing was in the midst of a scientific revolution. This position was soundly criticized, however, as ethnocentric and based on cavalier usage of Kuhn, such that a more appropriate reading of the field “indicate[s] the multi-paradigmatic nature of psychology . . . not [a] mature, oneparadigm-at-a-time science” (Warren, 1972, p. 1196). Although there are some authors who have rejected the value 3 Having come under attack for the plasticity of the word paradigm in his monograph, Kuhn subsequently acknowledged that it was used too broadly (Kuhn, 1977b; see also a relevant story in Kuhn, 2000, pp. 299 –300). 4 Not surprisingly, Kuhn’s stage model of scientific progress is very much like Piaget’s (1929) stage model of development. Piaget believed that children had to progress through developmental stages sequentially, with no skipping from Stage 1 to Stage 3, for example, and that there were clear characteristics that defined these stages. Perhaps not coincidentally, one introductory psychology text said, by way of explaining the current research that has found Piaget wrong on this count, “Our thinking may advance more because of our gradually increasing store of knowledge and ability to manipulate that knowledge efficiently than because of fundamental revolutions in our way of thinking” (Gray, 1999, p. 413). April 2003 ● American Psychologist of Kuhn applied to assessments of psychology’s status as a science, saying either that Kuhn’s model is fundamentally flawed (Suppe, 1984) or that other models of progress are more accurate (Gholson & Barker, 1985), he is widely used as an authority in these debates. Several American Psychologist articles and the comments elicited by those articles illustrate that these debates are extensive and mainstream. Leahey (1992) noted that the “history of experimental psychology in America is typically told as a series of two Kuhnian revolutions separating three periods of normal science dominated by the mentalist, then behaviorist, and finally today’s cognitivist paradigm” (p. 308) but that the evidence is in favor of nonrevolutionary change, so that if Kuhn is assumed to be right (an assumption Leahey did not make), it can be concluded that “psychology is not a science, because it has had no normal science and hence no revolutions” (p. 316; see also Briskman, 1972; Buss, 1978; Palermo, 1971; Peterson, 1981; Walter & Palermo, 1973). Friman, Allen, Kerwin, and Larzelere (1993) came to the conclusion that a scientific revolution, with cognitive psychology replacing behaviorism and psychoanalysis, indeed had not occurred. Robins and Craik (1994) argued, however, that examination of the preeminent journals in psychology indicated an ascendancy of cognitive psychology that just might “usher in the longawaited paradigmatic state of scientific psychology” (p. 816). Sperry (1993) argued more strongly for the cognitive revolution as a paradigm shift, and again there was a backlash of disagreement with this psychology-truly-is-ascience position (Hergenhahn, 1994; Holdstock, 1994; Morf, 1994). Staats (1991) maintained that psychology is not a science because it has always lacked a unified paradigm, that it is in a crisis of increasingly unmanageable fragmentation, and that the field “must achieve compact, parsimonious, interrelated, and consensual knowledge to be considered to be a real science” (p. 910; see Ardila, 1992, and Kirsh, 1977, for similar arguments). In response, S. M. Schneider (1992) suggested that the degree of integration is not so dire, Kukla (1992) that unification may not be such a clear recipe for improvement, and McNally (1992) that an understanding of Kuhn’s more recent work indicates that diversity in the field may signify vitality, not disintegration. Similarly, an introductory psychology text stated, “Though there are no longer separate schools of psychology with charismatic leaders and loyal followers, psychology still lacks a unifying scientific paradigm to which most psychologists subscribe” (Sdorow, 1990, p. 14). However, Henley, Johnson, Jones, and Herzog (1989) examined 233 introductory or general psychology textbooks published between 1887 and 1987 and found that definitions of psychology were predominately mental, then behavioral, and then cognitive, which they interpreted as signaling paradigms and paradigm shifts. There is, of course, not a clear answer to the question of whether or not psychology is a science. More accurately, the answer depends on where one draws lines around the term psychology, around the term science, and around Kuhn’s terms. What is clear from this usage of Kuhn is that the status of the field matters to psychologists. April 2003 ● American Psychologist Similarly, the status of one’s own work also matters to psychologists. This can be seen in another common form of Kuhn referencing, what may be best described as use for rhetorical leverage. It is this form of usage that is probably most responsible for the point of view opening this article, that psychologists’ Kuhn referencing is superficial, uncritical, and misinformed. It is easy to see why this is the impression formed by critics. Coleman and Salamon (1988) analyzed the 652 articles that cited Structure published in psychology journals between 1969 and 1983 and found that nearly half (48%) of the content-categorized comments reflected superficial usage of Kuhnian terms. Only 3% of the 652 were strictly about Kuhn or an application of Kuhn’s ideas. Of the 163 articles with coverage extensive enough for favorability ratings, 92% to 96% over the 15-year period were rated as being in “Total Agreement” with Kuhn’s theory. In addition, they found that psychologists tended to cite the 1962 edition of Structure rather than the less inflammatory 1970 edition. They concluded that Kuhn use has been chronologically stable, largely favorable, more frequent than any other philosopher of science, and generally superficial,5 and that it originates “in the impulse to magnify the significance of the author’s findings, conclusions, or reflections” (Coleman & Salamon, 1988, pp. 435– 436). The following five examples, at first blush, seem to support that view. They illustrate what is meant by rhetoric leverage, and they show that such usage crosses a range of subdisciplines. (a) “These lectures review the current state of the art in brain research to show that several lines of inquiry have been converging to produce a paradigm shift . . . in our understanding of the neural basis of figural perception” (Pribram, 1991, p. xxix). (b) “This article contends that changes are occurring so rapidly in innovative organizations that Kuhnian notions of ‘scientific revolutions’ do not adequately describe this phenomenon” (Shareef, 1997, p. 655). (c) “Most of the phenomena Kuhn has associated with paradigm shift can be observed in the emergence of self-psychology” (Galatzer-Levy, 1988, p. 4). (d) “In the past 25 years, a radically new understanding of Deaf people has appeared. This new understanding constitutes what Kuhn called a paradigm shift” (Glickman, 1996, p. 1). (e) “Connectionism as a method of modeling cognition as the interaction of neuronlike units . . . may represent a paradigm shift for psychology” (W. Schneider, 1988, p. 73). Each of these examples (and there are many others) invokes language from Structure to report progress that has 5 To extend Coleman and Salamon’s (1988) findings, I counted the number of citations in psychology journals from 1984 to 2001 in the Social Sciences Citation Index (SSCI), using the SSCI list of psychology journals. Adding that number (1,164) to Coleman and Salamon’s count from 1969 –1983 (652) and dividing the total by 33 (the number of years covered) gives an average number of citations per year of 55, as mentioned in the sentence opening this article. In keeping with Coleman and Salamon’s findings, the average number of citations is fairly steady; it has not decreased linearly over the years. A spreadsheet of the citations and a table of number of citations per year are available on request. 275 occurred in particular research areas. These works no doubt represent valuable contributions, but they illustrate a tendency to overextend Kuhn’s argument and a failure to grasp the subtleties of Kuhn’s model of progress. For example, revolutions are meant to signify shifts in the field as a whole, not in niche areas. Is it, however, fair to designate such usage, as Coleman and Salamon (1988) and others have, as purely and intentionally sophistic? Kuhn’s position on truth and his model of progress reframe the admirable in science. If truth is not absolute, knowledge does not accumulate. Thus, success can no longer be adequately measured by finding fitting solutions to focused problems (this is Conant’s point about ignoring minor advances). Use for rhetorical leverage shows that psychologists look for and are willing to wave what they believe are Kuhnian signs of the admirable—revolutions and paradigm shifts—when it is more likely that their results signify minor advances. However, it is easy for critics to miss the fact that such usage, and the pervasiveness of this usage, may originate from a deeply held desire for psychology, and for psychologists, to be admirable. Summary and Conclusions I have argued that Kuhn’s position on truth and his psychologized model of scientific progress have made Structure an especially appealing resource for psychologists and that the nature of this appeal can be seen in the ways psychologists reference Kuhn. A key piece of this argument is the proposition that psychologists study phenomena that are inherently multileveled, that require both natural and social levels of analysis (by phenomena, I am referring to broad terms or classes— e.g., learning, schizophrenia, emotion, consciousness, etc.). This means that the field necessarily encompasses contradictory traditions, assumptions, and methods and accordingly that psychology has consistently been perceived from within and without as splintered, in a state of crisis. I have also argued that Kuhn’s naturalistic position on scientific truth may hold an implicit appeal to psychologists because it bridges these divisions, falling between a natural/rationalist stance and a social/relativist stance. However, it is Kuhn’s model of scientific progress that seems to have held the greatest explicit appeal. Kuhn’s model of progress relies on psychology, and it presents a point of view that seems normative; it can be read to say something akin to the following: A science is like a person, with identifiable stages of development. So, when one has a collection of scientists who are attuned to signs of developmental progress (because they are divided) and a popular text that seems to identify stages of development, one gets frequent referencing to assess the developmental status of the field and to laud individual development. In some ways, the above-told history of mutual influence—Kuhn’s use of psychology and psychologists’ pervasive referencing of Kuhn— highlights that of which psychologists are all too acutely aware: The field lacks an enduring scientific identity. It also, though, highlights that, in general, psychologists seem far more concerned with what signifies comparative progress than with generating or 276 maintaining a vision for where the field is going. To use the terms from a quotation earlier in this article, if psychology’s “dozens of characters in search of a play” want to produce something other than a “tumble of programs, promises, and proclamations,” there would be some benefit to attending to “what it is, as we say, ‘about’—what sort of knowledge, of what sort of reality, to what sort of end” (Geertz, 2000, pp. 187–188). To what sort of end? Two norms seem to me to be especially contradictory in light of the overarching or longterm goals suggested by the above analysis. First, suppose that psychologists really do want to understand phenomena that cross levels of analysis, that require more molecular, natural science methods as well as more molar, social levels of analysis. It would seem that to do so would require a value placed on synthesis, meta-analytic perspective, and cross-area expertise. Why, then, in practice, are history of psychology and philosophy of science relatively undervalued and breadth so routinely sacrificed in favor of specialization? Second, suppose that psychologists tend to favor a Kuhn-like, naturalistic, middling stance on truth in science—to believe that there is truth without claiming that results are not historically, culturally, and psychologically limited. Why, then, is there such a strong norm for using language of justification in journals and grants instead of an explicit acknowledgment that such products (like this one) are not truth but instead represent works in progress, as surely they all must? 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This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. York University Over the past few decades, a large literature has emerged on the question of how one might unify all or most of psychology under a single, coherent, rigorous framework, in a manner similar to that which unified physics under Newton’s Laws, or biology under Darwin’s theory of natural selection. It is argued here that this is a highly unlikely scenario in psychology given the contingent and opportunistic character of the processes that brought its original topics together into a new discipline, and the nearly continuous institutional, social, and even political negotiating and horse-trading that has determined psychology’s “boundaries” in the 14 decades since. Psychology, as the field currently stands, does not have the intellectual coherence to be brought together by any set of principles that would enable its phenomena to be captured and explained as rigorous products of those principles. If there is a kind of unification in psychology’s future, it is more likely to be one that, paradoxically, sees it broken up into a number of large “super-subdisciplines,” each of which exhibits more internal coherence than does the current sprawling and heterogeneous whole. Keywords: psychology, history, philosophy, theory, unity In psychology, there have been many proposals for a similar kind of unification. American Psychologist was long a prime venue for such work (Kimble, 1989, 1994, 1999; Staats, 1981, 1991; Sternberg & Grigorenko, 2001). Since the founding of The Review of General Psychology, it has become a popular vehicle for them as well (Marsh & Boag, 2014; Staats, 1999; Yanchar & Slife, 1997), highlighted by a special issue on the topic in 2013 (Anderson, 2013; Catania, 2013; Charles, 2013; Chemero, 2013; Clegg, 2013; Heft, 2013; Henriques, 2013; Hutto, 2013; Lerner, Agans, DeSouza, & Gasca, 2013; Lickliter & Honeycutt, 2013; Marken & Mansell, 2013; Mayer & Allen, 2013; Petocz & Mackay, 2013). Proposals for the unification of psychology have hardly been confined to these two journals, however. There have been others as well (e.g., Goertzen, 2008, 2010; Henriques, 2004, 2011; Kimble, 1996; Staats, 1983; Kristensen, Slife, & Yanchar, 2000; Stam, 2004, 2015). An interesting counterpoint to these diverse efforts can be found in Sigmund Koch’s call to concede that psychology cannot be unified and to rename the field “psychological studies” (Koch, 1993).3 The question of whether psychology can be “unified” is one that has long occupied the discipline. In order to be “unified” in the sense I intend here, the discipline would have a common set of foundational principles from which detailed descriptions of its phenomena could be rigorously derived and by which they could be explained.1 It seems that if only psychologists could agree on these fundamentals—the mental and/or behavioral “elements,” and the basic principles of their interactions—then the discipline would start making the kind of impressive progress that we have seen in natural science over the past few centuries. The most commonly raised example of this kind of unification is found in physics, which is often said to have been unified under Newton’s Laws which were, in turn, reliant on his mathematical discoveries. Another prime example is in biology, large parts of which were unified under Darwin’s theory evolution by natural selection.2 One of the most significant aspects of these two epochmaking scientific developments is that they not only provided a common explanatory framework for disparate aspects of complex fields of study (e.g., respectively, the motions of both terrestrial cannon balls and of celestial planets; the seemingly ubiquitous hierarchical arrangement of species in both the animal and plant kingdoms), but they were later extended and adapted to provide explanations for phenomena that were either unknown or poorly understood at the time the framework was first proposed (e.g., electrical force; the development of antibiotic resistance), thereby strengthening the unity of the field even further. 1 I contrast this sense of unification with another that is often offered: mere descriptions of high-level similarities among diverse research areas. These do not unify a discipline in any ...
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