What is the relationship between philosophy and psychology?

Introduction

The relationship between philosophy and psychology is complex. Psychology has its origins in philosophy, and until the mid-twentieth century, psychology was part of the philosophy department at universities. Psychology is often held to have split off from philosophy in 1879, with the founding of Wilhelm Wundt’s experimental psychology laboratory in Leipzig, Germany. To recognize the split is to define psychology as an empirical science, as many have done. However, psychology and philosophy address many of the same questions, questions that have puzzled people since time immemorial and that have been addressed not only by psychology and philosophy but also by religion, anthropology, political science, and other social sciences and humanistic disciplines. Not all those questions can be or have been addressed empirically, and the empirical work of psychology has raised many philosophical questions in its own right. The concerns addressed by both disciplines include questions of metaphysics (including ontology), epistemology, and moral philosophy (ethics), although the distinctions between these areas often blur, and other topics have also been addressed by both disciplines (such as phenomenology and hermeneutics).

Philosophical Origins of Psychology

Many trace the origin of psychology to the ancient Greek philosophers, particularly Socrates, Plato, and Aristotle. Certainly, topics such as the ones favored by the philosophers were being addressed long before psychology developed a disciplinary identity. Throughout the Middle Ages, philosophers and theologians such as Peter Abelard, Thomas Aquinas, Saint Bonaventure, and William Ockham explored the realm of human knowing, thinking, feeling, and sensing, although without the extensive empirical investigation of these states that came to characterize the psychological method. From the time of the Renaissance, philosophers such as René Descartes, Thomas Hobbes, John Locke, George Berkeley, David Hume, James Mill, John Stuart Mill, and Immanuel Kant debated the topics that have come to be central to the discipline of psychology.

Metaphysics

Metaphysics is the branch of philosophy that addresses questions regarding the nature of reality and the sorts of things that exist in the world. In modern philosophical usage, this branch includes questions of ontology, including the philosophy of mind. Both psychology and philosophy are concerned with the philosophy of mind. The philosophy of mind traces its origins to the ancient Greek philosophers, as well as Franz Brentano, William James, and John Dewey, among others. The philosophy of mind has primarily been concerned with three questions: the meaning of intentionality, the mind-body problem, and the problem of free will versus determinism.

Philosophers have asked what it means to have intentionality. Some have asserted that mental states, such as wishing, believing, and thinking, are necessarily about something, which is termed the “intentional object” of the mental state. (For example, I think that it is almost time for dinner; I wish that my homework were done; I believe I can succeed.) However, this raises the question of whether intentions “cause” actions, in a strict philosophical sense. This line of thought has been pursued by the philosophers Ludwig Wittgenstein, Donald Davidson, and Derek Parfit.

The philosophy of mind also looks at the relationship between the mind and the body (the mind-body problem) and asks: If all mental acts arise from physical states, what claims are left for the realm of the purely mental, rather than physical? The mind-body problem is related directly to questions regarding idealism versus materialism (whether the world is reducible to ideas or to the material world) and indirectly to questions of free will versus determinism. It is also related to questions of dualism versus monism (for example, the question of whether there are two sorts of things in the world or one). Under dualism, if the brain and mind (or body and mind) are wholly separable, questions arise concerning how the two are linked and how something that has no physical properties might be related to, communicate with, or affect something that has exclusively physical properties. These types of questions have been addressed by research in cognitive neuroscience by scientists such as Paul Churchland and Patricia Churchland and by philosophers such as Davidson and Thomas Nagel. However, if mind and brain are assumed to be the same (monism), other questions arise. For example, if mental states are wholly determined by physical changes in the brain, in what sense is it possible to claim that human beings have free will?

Free will versus determinism is the third question addressed by the philosophy of mind. Although this issue is not completely separate from religious questions treated by philosophers and theologists, the question has taken a different form in psychology. Psychologists as varied as the American behaviorist B. F. Skinner and the Viennese psychoanalyst Sigmund Freud have held that human behavior is determined, either by conscious or unconscious forces, while the early American psychologist William James and the American founder of person-centered therapy Carl R. Rogers, as well as other humanistic and existential psychologists, have held that humans have free will. However, if humans have free will and therefore can make choices that are independent of antecedent conditions, the question arises of whether psychology is a science in the sense of being a discipline that can make reliable predictions that can be tested and produce results that can be replicated by others.

Epistemology

Epistemology is the branch of philosophy devoted to the question of how people know what they know. This includes questions regarding the nature, scope, and possibility of any knowledge, and psychological knowledge. Both psychology and philosophy have wrestled with such epistemological questions as the nature of consciousness, the possibility of intersubjectivity (how people know others’ minds), and how people know their own minds.

The nature of consciousness has been a central question of both psychology and philosophy. This topic has been explored phenomenologically, including by Freud, and also through an attempt to identify the neural correlates of consciousness, a method pursued by cognitive neuroscientists as well as the philosopher John Searle. Questions regarding consciousness have become increasingly intriguing with the discovery of functional magnetic resonance imaging (fMRI), which permits correlation of the structures of the brain with the functions that they are performing in real time. Included in the study of consciousness are questions regarding sensation and perception, which raise philosophical problems, including whether the sensation of the object is separate from the perception of it, the knowledge of it, or both.

The problem of other minds, or intersubjectivity, has been of concern in both psychology and philosophy. It has taken many forms, including questions regarding how people know that others have minds and how they can have knowledge of others’ mental states. Philosophers Daniel Dennett and Davidson in particular have addressed this question. In psychology, this question is central to both clinical practice and research methodology, insofar as both depend on understanding the minds of those whom psychologists are studying and treating.

The question of how well people can know others’ minds leads directly to a third question, namely, how people can know their own minds and whether introspection is possible and by what means. Philosophers have asked how people can be sure about the contents of their own minds and on what authority they issue claims about their self-knowledge. They also ask what the relationship is between people’s claims of self-knowledge and the language they use to express them, as well as how to validate what people say about themselves. These questions have been pursued by the philosophers Wittgenstein and Davidson and the cognitive scientist Jerry Fodor. Such questions have clear implications for introspective (talk) psychotherapies, which rely heavily on first-person assertions by clients regarding their mental states.

Philosophy of Science

The philosophy of science is primarily concerned with the question of whether and to what extent the claims made by empirical psychology can be justified; that is, whether psychology is in fact a science like chemistry and physics. This critique has its origin in the work of the philosopher of science Thomas Kuhn, who pointed out that sciences move forward through a process of paradigm shifts, in which previously inchoate data or anomalous data become organized by a new explanatory rubric that better accounts for them than the previous theory did. By such standards, many have concluded that psychology is a preparadigmatic science. The work of philosophers Karl Popper and Paul Feyerabend is related to this topic.

Psychoanalysis in particular has been concerned with questions of whether its findings are best judged by scientific criteria (a correspondence theory of truth) or by hermeneutic or aesthetic criteria (coherence or parsimony). This debate has gained force because the status of psychoanalysis as a medical, and therefore presumably scientific, treatment rests on data obtained through the methods of free association and recollection, which raise unique philosophical problems. This debate has often taken the form of whether psychoanalysis is a hermeneutic pursuit, with the philosopher of science Adolf Grunbaum and the American psychoanalysts Donald Spence, Arnold Modell, and Roy Shafer weighing in on the matter.

Moral Philosophy

Moral philosophy is the branch of philosophy that concerns ethics. Although ethics has been a major topic in philosophy, psychology’s concern with ethics has been largely restricted to questions regarding the treatment of human and animal subjects in experiments and patients in clinical practice. Less attention has been devoted to broader questions of the place of values in human life, and such work has rarely drawn on the related work in moral philosophy.

Phenomenology

Phenomenology is a branch of philosophy that studies people’s conscious experiences of the world. Its premise is that reality is based on how objects and events are perceived or understood by the human consciousness and not on anything independent of human consciousness. Its philosophical origins are to be found in the works of Martin Heidegger, Edmund Husserl, Maurice Merleau-Ponty, Paul Ricoeur, and other twentieth century European philosophers. Its concern with first-person subjective mental states made phenomenology a natural fit for the emerging discipline of psychology, and existential and humanistic psychology in particular have conducted research to test phenemonological assertions as a guide to effective treatment. The work of the American person-centered psychologists Carl R. Rogers and Eugene Gendlin and the existential Swiss psychiatrists Ludwig Binswanger and Medard Boss have been influential among clinicians interested in phenomenology. The Society for Theoretical and Philosophical Psychology has served as one intellectual home for those interested in such topics.

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