Should psychology follow the methods and principles of the natural sciences? Introduction to the debate

Abstract

This debate issue centers on the question of whether psychology should follow the methods and principles of the natural sciences. Answers to this question are often implicitly assumed but rarely explicitly debated among psychologists. This issue contains eight invited contributions by scholars whom we anticipated would have strong and divergent positions on the question. The articles present a broad range of perspectives, ranging from phenomenological psychology to cognitive neuroscience. They broadly line up with a “yes” or “no” answer to the question, four authors favoring a “yes” and four authors a “no” response, although nearly all authors advance more nuanced positions that challenge a simple classification. In this introduction, we first discuss the historical roots of the question and our motivation behind this specific formulation of it. Then we briefly summarize the contributions and place them in a broader context.

Keywords

Humanities methods natural science psychology science

The debate

Psychology, straddling the border between the humanities, social sciences, and natural sciences, has long grappled with its scientific identity. On one hand, this interdisciplinary nature enriches the field, offering diverse perspectives, but on the other, the question of disciplinary identity can function to divide psychologists and encourage the formation of distinct epistemic communities. The aim of this issue is to approach this topic in the form of a debate, putting forward different and often conflicting views in response to the question: Should psychology follow the methods and principles of the natural sciences?

The initial motivation for this debate issue stemmed from our impression that psychologists rarely reflect on this issue explicitly, but tend to tacitly assume a strong position on it: Of course psychology should be a science! Or: Of course psychology is not a science, and should not pretend to be one! The former position, assuming psychology to be part of the natural sciences, is also clearly reflected in typical psychology curricula, which focus heavily on statistics and empirical methods instead of qualitative or conceptual approaches. The latter position has been an impetus to progress in the development of qualitative methods, as well as alternative approaches to psychology including phenomenological psychology (Wertz, 2015), critical psychology (Parker, 2007), and articulation of a “psychological humanities” (Freeman, 2023; Teo, 2017).

With this in mind, our initial plan was to find contributors who take a clear “yes” or “no” position on this question, and to pit them against each other, leading to a debate issue with two opposing camps represented somewhat equally. However, contrary to our expectations, this soon turned out to be untenable. It was difficult to find experts willing to take a strong and unequivocal “yes” or “no” position on our question. Almost all of those we approached took issue with the question itself. On the “yes” side, most contributors we had in mind made clear that their views are actually more nuanced and do not amount to a clear “yes” answer. And, even on the “no” side, scholars tended to favor pluralistic stances that allowed for some aspects of psychology to follow the natural sciences. For this reason, we changed our plans, and attempted to represent the whole breadth of views on this issue, without a dividing line that would not do justice to the positions taken.

This raises some interesting questions: If most psychologists, when reflecting on this question, have a rather nuanced view, why do the dividing lines appear to be so strong in contemporary practice, as well as in professional and public discourse? Why do psychologists doing experimental psychology on the one hand and qualitative psychology or psychological humanities on the other hand have their own communities, journals, and societies, with little interaction between each other? Why do so many undergraduate textbooks present psychology straightforwardly as a “science” without clearer discussion of what this might mean? Why do so many professional associations advocate so strongly and unwaveringly for psychology to be categorized as a science, when many leading scholars in those associations seem to hold more nuanced views?

A long history behind the question

Disagreement surrounding the scientific status of psychology is far from new; it has accompanied psychology throughout its history. An early example is Ward’s (1904) essay on psychology’s ambiguous subject matter and the problem this creates: “For some it is the central philosophical discipline; for others it is but a department of biology. According to one view, it is a descriptive science; according to another, it is explanatory as well” (p. 603). Ward’s concern was that deep divisions in psychology’s identity would slow or derail any progress it might hope to achieve as a distinct discipline, scientific or not. Much later, Koch (1981) attested that he had been addressing the question of whether psychology is a science for the past 40 years.

There are, moreover, variations in the way the question of psychology’s scientific status has been taken up across time and by different communities, and in relation to specific problems or research traditions. Movements such as humanistic, phenomenological, narrative, and other approaches to psychology align with a human science tradition and the method of understanding (Verstehen) human life that Dilthey (1883/1989) contrasted with the goals of explaining (Erklären) the facts of the natural world. In personality psychology, the personology tradition that focuses on the study of particular lives over time has developed in parallel with the nomothetic framework of common trait analysis. For social psychology, attention to language, conversation, and social norms has offered a robust alternative to experiments testing the relation between variables (e.g., Potter & Wetherell, 1994). In cognitive science, frameworks emphasizing the situated and enactive nature of learning and problem solving call for system-level interpretive analysis (e.g., Lave & Wenger, 1991).

Finally, we should note that in some contexts, the stated goal has been to expand the conceptual and methodological scope of psychology, as in Koch’s (1993) eventual articulation of the “psychological studies” as an alternative model to “psychological science” and in some contemporary calls for pluralism as a more adequate foundation for psychology’s diverse subject matter (e.g., Goertzen & Smythe, 2010).

Formulating the question

Before we started inviting contributions, we had several discussions on how exactly to formulate the question, and we were ourselves aware that the question might be perceived as problematic. There are many similar questions to the one we have selected as the focus for this issue, each of which is interesting and important in its own right. For example: How and when did psychology come to be considered as a (natural) science? This is an interesting historical question, and is touched upon in some of the contributions (e.g., Fernandes, 2024; Proctor & Warren, 2024), but is not a core question of this issue. In particular, while relevant, this question does not get at the issue of whether contemporary psychologists feel that psychology should be considered a science, separate from its historical trajectory. Another question that is often asked: Is psychology a science? One of us (O’Doherty) regularly asks this question of undergraduate students of whom a minority would say, no, it does not measure up well against other natural sciences in terms of rigor and precision, and so should not be considered a science. The majority of students respond by saying, yes, of course it is a science (likely because this is what has been consistently asserted in their textbooks). When pushed to give a reason for their answer, a common response is “because it follows the scientific method.” Further probing as to what the scientific method is leads to awkward silences, questioning glances, and suggestions like the testing of hypotheses and the use of statistics.

The problem with the question “Is psychology a science?” is that it tends to invite unreflective and shallow answers that do not dig into deeper issues such as whether “science” includes only the natural sciences or also the social and human sciences; what criteria one might select to adjudicate a discipline as being scientific or not; and why being or not being a science would be seen as such a terrible pronouncement. Perhaps most importantly, the question does not include a normative element—should we conceive of psychology as a science, and what would be the consequences of doing so or not doing so? For these reasons, we formulated the question to guide this debate as: Should psychology follow the methods and principles of the natural sciences?

The purpose of phrasing the question in this way is to highlight several issues. First, the normative aspect (“should”) emphasizes that we have a choice in this matter. “Science” is a human activity, and so it is a category that is flexible and contested. Whether something is considered a science is not a matter of fact; rather, it is at least partly a matter of social convention. Second, by emphasizing “methods and practices” we are drawing attention to the observation that there is no such thing as “the” scientific method; as philosophers, sociologists, anthropologists, and historians of science have shown quite convincingly, there is no single method that is followed by all scientists for all domains of science. Rather, the term “science” points to a heterogenous set of practices, institutions, and knowledge claims, sometimes contested, sometimes with strong consensus. The phrase “methods and practices” is thus intended to deny simplistic responses that appeal to the common trope of “the scientific method” as a justification for including or excluding psychology from the category of being a science, and instead draw attention to the plurality of approaches that constitute scientific practice. Third, using the term “natural sciences” rather than just “science” is intended to highlight an assumption that often remains implicit. In English, the scope of the term “science” is narrower than the corresponding term in many other languages, such as German, Dutch, or Finnish. In German, for instance, “science” is typically translated as “Wissenschaft,” and Wissenschaft includes a range of scholarly disciplines, even those that in English would be categorized as being part of the humanities or social sciences (see also Gigerenzer, 2024). In the English-language domain, when there is discussion about whether psychology is a science, the implied comparison is typically to the natural sciences, though this is rarely made explicit. The problem with this is that all too often, when something is said to be “not scientific,” the implication is that it is not truly knowledge; it is “just” anecdotal or even pseudoscience. Making explicit the comparison to the natural sciences in our question is thus intended to direct attention specifically to what psychology is compared against and what might be left out when making that comparison.

We are well aware that our question formulation includes other assumptions, and in keeping with psychology’s vague identity, we might be accused of further obfuscation by submitting a vague question for debate. The formulation that we chose indeed contains key terms that are open to many definitions and interpretations. Our intention was to leave it up to the contributors to interpret the question. And we were delighted that the contributors to the debate pushed back against the question, interrogated the assumptions inherent in its framing, and used the opportunity of this debate to develop sophisticated arguments that go well beyond a simple yes/no answer to the question. Notably, different authors pushed back against the question in diverse ways, leading arguments in very different directions. Gigerenzer (2024), for example, pushes back against the assumption that there is an identifiable set of methods or principles that is sufficiently common among the natural sciences, and thus for psychology to emulate wholesale. In contrast, Tafreshi and Slaney (2024) push back against the notion that “good science” is about methods in the first place, and argue that any methods one uses should be preceded by sound conceptual analysis. Beaujean (2024) pushes back against the assumption that “psychology” is one coherent thing. Derksen’s (2024) contribution dissects the entire question and analyses its different components, such as “the natural sciences” or “the methods and principles.” Therefore, we can conclude that the formulation of the question led to very fruitful deliberations.

Summary of contributions

When we invited contributors to consider the question “Should psychology follow the methods and principles of the natural sciences?” we purposefully approached scholars who we anticipated would have strong and divergent positions on the topic. We were not disappointed, and the articles published in this issue do indeed demonstrate very different orientations on the topic. Although few contributors took a straightforward position, they all broadly line up with a “yes” or “no” answer to the question, four authors favoring a “yes” and four authors a “no” response (though some, such as Beaujean, 2024, are difficult to place). We structured the issue with alternating responses, roughly according to this “yes/no” binary.

The special issue starts with an article by Gigerenzer (2024), who argues that psychology has much to learn from the natural sciences. Nevertheless, he also observes that psychology is still stuck in the “null ritual,” based on null hypothesis significance testing, which he argues is neither based on the natural sciences nor a good method for doing science at all. In particular, psychological researchers should focus more on constructing theories about psychological processes instead of just “as-if” or surrogate theories that in the end do not explain anything.

Derksen (2024) focuses directly on the question itself, and critically examines all of its different components: “should,” “psychology,” “follow,” “the methods and principles,” and “the natural sciences.” Regarding the answer to the question, he shares with Gigerenzer (2024) the sentiment that psychology can learn from the natural sciences (among many other sources). However, Derksen (2024) is strongly against any prescriptions on what scientists should or should not do. He argues that psychologists are free to selectively adapt from the broad array of available methodologies, which includes the methods and principles of natural sciences, but also the methods and principles of human sciences, and even approaches from traditions like philosophy and art. By advocating for pluralism, Derksen encourages embracing the diversity of the field of psychology.

Proctor and Warren (2024) take perhaps the clearest “yes” stance on our question: From an historical perspective and organizing their response to the question around the concept of worldviews, they argue that scientific psychology has its roots in the departure from contextualist and subjective approaches, and that mechanistic and contextualist worldviews are in fact incompatible. They offer historical evidence to support their position and claim with reference to empirical examples that a mechanistic worldview is needed to further develop psychology as a science. Therefore, although they do not answer our question directly, implicit in their argument, at least, is a defense of the position that psychology should follow the methods of experimental sciences and should be treated as a natural science.¹

In stark contrast to the views of Proctor and Warren (2024), Teo (2024) argues that a natural-scientific approach to psychology, with its focus on the operationalization and variabilization of concepts, is epistemically insufficient to capture the complexity of psychological phenomena. This is because human mental life is embedded in history, culture, and society, and psychological phenomena are contextual and temporal. While Teo does not reject natural scientific methods, he argues that empirical psychology needs to be complemented with “armchair” approaches of the psychological humanities, such as conceptual reflection on the cultural, historical, and societal dimensions of subjectivity.

Beaujean (2024) frames the question orienting the special issue as “the fundamental problem” that has plagued psychology from its earliest instantiations as an empirical pursuit, traceable to even earlier debates. He argues that the fundamental problem is based on two problematic assumptions: first, that psychology has a coherent and unitary subject matter; second, that methods of natural science are uniform. Exposing these, he declares the fundamental problem to be unsolvable, and thus only an approach tailored to the specific research question and subject matter has methodological integrity. He illustrates his claim by analyzing differences between two emotion concepts (fear and courage), demonstrating distinct features in their meaning and contexts of use that call for different frameworks and methods.

Tafreshi and Slaney (2024) defend a broadly Wittgensteinian approach to psychology. They argue that psychology’s preoccupation with adopting natural science principles often overlooks conceptual issues that need to be resolved first. They argue that psychologists should first carefully consider and analyze the concepts of interest, and only after that, determine what methods are appropriate. In many cases, according to them, the methods and principles of the natural sciences are not a good fit for studying psychological concepts, which in the end stem from ordinary language but often end up being treated as technical concepts. The paper emphasizes the importance of a conceptual approach to psychological research, and suggests that the question of this debate issue can only be answered on a case-by-case basis.

The contribution by Fernandes (2024) takes a “yes” stance with regard to our question. Fernandes discusses how cognitive neuroscience, which can be seen as a (highly influential) branch of psychology, seeks to identify the neural basis of cognitive capabilities and functions. Fernandes emphasizes the historical and modern methodologies that have shaped the field, ranging from the debunked practices of phrenology to current sophisticated neuroimaging and brain stimulation techniques. Key methods like the double dissociation technique, neuropsychological testing, and the subtraction method in neuroimaging have substantially contributed to understanding brain–behavior relationships and cognitive functions like language, memory, and decision-making. The article argues that the application of natural science methods and principles in cognitive neuroscience has the potential to lead to significant advances in explaining and predicting human behavior. However, even Fernandes does not take an unequivocal “yes” position, and allows for the importance of complementary methods that delve into subjective elements of experience.

Wertz’s (2024) article comes last in our order of contributions because of the comprehensive and interdisciplinary point of view he brings to bear on the debate. Wertz aligns his thinking with that of phenomenology, especially Husserl, whom he depicts as fundamentally concerned with the nature of psychology and its relation to natural science. Wertz argues, however, that although Husserl’s primary concern with causality and meaning underscores the enduring relevance of his position, new and original analysis of the question of psychology’s scientific status is very much needed in the present context. In developing this point, he makes note of transformations in natural science itself, more nuanced accounts of scientific practice, and broadening directions of empirical psychology, both in subject matter and empirical methods of inquiry. The conclusion that emerges is that fine-grained and particularized analysis is needed to discern in what sense and to what extent psychology is similar and/or different from other sciences.

One common thread among these contributions is the observation of a lack of attention to theory (understood in the broadest sense) prevalent across contemporary psychological sciences. This sentiment is shared both by advocates of natural scientific methods and by those emphasizing the need for conceptual and humanistic approaches. It is also reflected in recent proclamations of a “theory crisis” in psychology, which come with diverging proposals on how exactly to address it (e.g., Borsboom et al., 2021; Eronen & Bringmann, 2021; Guest & Martin, 2021; Oberauer & Lewandowsky, 2019; see also Gigerenzer, 2010; Klein, 2014). Whatever the reasons and solutions, the call for more theory in psychology seems to be one uniting factor of otherwise different and sometimes antagonistic approaches to psychology.

Recently, Michell (2023) drew attention to the extremely strong quantitative imperatives that motivated key founding figures of psychology, with Galton’s (1879) entrenched position being particularly noteworthy: “until the phenomena of any branch of knowledge have been subjected to measurement and number, it cannot assume the status and dignity of a science” (p. 149). Whether one agrees or disagrees with this perspective, we hope that this debate issue forms a starting point for further informed discussions on the relationships between psychology and other scholarly disciplines, including the natural sciences. Therefore, we also invite readers to submit their own views on this issue. Both comments on some of the individual articles and on the issue as a whole are welcome as regular submissions to the journal.

Footnotes

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Notes

Author biographies

Markus I. Eronen is an assistant professor at the Department of Theoretical Philosophy, University of Groningen. His primary field of research is the intersection of philosophy of science and theoretical psychology. This includes issues such as causal discovery and downward causation, levels and reductionism, and the role of theory in psychology. He has published on these topics in both philosophical and psychological journals, including Philosophy of Science, Philosophical Psychology, Perspectives on Psychological Science, and Psychological Medicine.

Lisa M. Osbeck is a professor of psychology in the Department of Anthropology, Psychology, and Sociology at the University of West Georgia. Her interests concern philosophy of psychology, psychology of science, and general psychology. She is a fellow of the American Psychological Association (Divisions 1, 5, and 24) and the Center for Philosophy of Science, University of Pittsburgh, as well as a past president of the Society for General Psychology (APA Division 1). Her most recent books are (with S. Araujo) Ever Not Quite: Pluralism(s) in William James and Contemporary Psychology (Cambridge, 2023); and (with S. Antczak, Ed.) Person-Centered Studies in Psychology of Science (Routledge, 2022).

Kieran C. O’Doherty is professor in the department of psychology at the University of Guelph, where he directs the Discourse, Science, Publics Research Group. His research focuses on the social and ethical implications of science and technology. In this context, he has published on such topics as data governance, vaccines, human tissue biobanks, salmon genomics, and the human microbiome. Kieran’s research also emphasizes public deliberation as a mechanism for dialogue between publics, experts, and policy makers. In this regard, he has designed and implemented deliberative forums in which members of the public engage in in-depth discussion about ethical aspects of science and technology and collectively develop recommendations for policy. Recent edited volumes include Psychological Studies of Science and Technology (2019) and The Sage Handbook of Applied Social Psychology (2019). Kieran’s research has been funded by the Canadian Institutes of Health Research, the Office of the Privacy Commissioner of Canada, the Ontario Ministry of Research & Innovation, Genome Canada, and Genome British Columbia.

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