Descartes and Kant: Philosophical Origins of Psychology

Psychologists today would no doubt insist that psychology is a discipline separate and distinct from that of philosophy. The mere fact that psychology is thought of as a science sets it apart from philosophy and, at times, makes it quite incompatible with philosophy. Yet psychology and philosophy are bound by history in that it is from philosophy that psychology receives the methods that psychology employs in analyzing and evaluating the mind and all that it entails. Psychology owes its existence to a great number of philosophical thinkers including Aristotle, Plato, John Locke, and David Hume. Here, I shall focus on the particular influences of Rationalism, specifically focusing on the work of René Descartes and the counterarguments of Emmanuel Kant.

René Descartes was a very private man and the details of his life are only vaguely known. Born in 1596, he was an intellectually bright child and was enrolled in the College at la Flèche at the age of 10. Some time after graduating at the age of sixteen, Descartes took up residence in the Paris suburb of St. Germain. Here, between periods of seclusion, Descartes observed the workings of a set of mechanical fountain statues that had been built for the Queen. Watching these, he developed an idea that real bodies, animal and human, operate much like these automata—utilizing a system of hydraulics and fluids to animate the body and its processes. This idea would prove to be the basic idea involved in his later physiological theories of the brain and visual perception (Fancher, 1979, chap. 1).

After moving and becoming reclusive once again, Descartes found himself dissatisfied with the uncertainties of much of the information he had learned in school and afterward. He was pleased with the certainties that mathematics offered, but as of yet there were not many ways to apply math to other disciplines. One morning during the course of these frustrations, Descartes found himself watching a fly on the wall (or so the story goes) and suddenly discovered that he could define the fly’s position using only three numbers: the perpendicular distance of the fly from each wall and from the ceiling. Generalizing from this realization, he discovered that any point in space could be defined in a similar way by measuring their distances from perpendicular lines or planes. These numbers have commonly become known as “Cartesian coordinates” and the perpendicular lines as the x- and y-axes. That discovery led to the development of analytical geometry, the first mathematical blending of algebra and geometry. The discovery of the coordinate plane, alone, is a huge contribution to psychology, for without it, defining the relationship between independent and dependent variables, calculating correlations, performing tests of significance, and other quantitative analysis would not be possible (Fancher, 1979, chap. 1).

After this discovery, Descartes began to wonder if there were other knowledge areas that could provide answers or facts with the same amount of certainty of results as mathematics. Able to think of none, he proceeded with enumerating the faults of then-current scholarship and ultimately concluded that the best course for him to follow would be to disregard everything he had learned and only accept as “truth” those things which he could determine were correct or valid through his own systematic reasoning. To this end, Descartes formed a method for such reasoning that he believed would offer other disciplines the same amount of certainty afforded by mathematics. This method consisted of four rules, stated briefly they are:

1. To proceed by means of doubt, to take nothing for granted, to avoid bias and prejudgment;

2. To divide the substance of the argument into the simplest parts;

3. To proceed step by step from the simple to the more complex;

4. To “enumerate” and review so as to make sure nothing is missed in the argument, and that as many sources for the correct conclusion as possible may be collated (Turner, 1965, p.18).

Descartes was sure that this method would provide the mathematical elements needed to produce valid and reliable results in scholarly thinking.

The first rule of this method, however, was especially troubling to Descartes. Already plagued with doubt about many other supposed truths, Descartes began to doubt everything until he even doubted that he, himself, existed. After a long process of doubting and reasoning, he doubted his existence until he realized the only thing he could no longer doubt was that he doubted. He reasoned that because he could not doubt that he was presently doubting, he must at least exist in order to be doubting. It is from this doubting, and subsequent realization and affirmation of existence we obtain the oft-quoted “I think, therefore I am,” or “Cogito, ergo sum.” (Balz, 1952). By proving that he, himself, existed, Descartes reasoned that he could also prove other things to be logically and rationally true by using the method he created.

Like the development of analytical geometry, the ideas contained in his methodology constitute a large contribution to the future of psychology in that it is precisely from the principles Descartes laid out in his method that deductive and inductive reasoning developed. More importantly, the introduction of methodology for the precise and systematic evaluation and verification if ideas or supposition was crucial to the development of the field of science in general, but particularly the field of psychology. Descartes’ method provides the fundamental building blocks of the scientific method that modern sciences hail as a core procedural guideline. We, like Descartes, are satisfied that if all of the rules of the scientific method are followed exactly, the results should be valid and dependable.

Descartes made yet another important contribution to the future field of psychology immediately after his realization that he did indeed exist. As he made this realization, he also realized that he could be sure that the mind and body were separate from one another:

I concluded that I was a thing or substance whose whole essence or nature was only to think, and which, to exist has no need of space nor of any material thing or body. Thus, it follows that this ego, this mind, this soul, by which I am what I am, is entirely distinct from the body and is easier to know than the latter, and that even if the body were not, the soul would not cease to be all that it now is (Descartes, 25).

This was an important distinction at this time, for the majority of discourse had concerned the workings of the soul with the assumption that the soul controlled most aspects of the body. It had been supposed that the soul was the seat of all reasoning, thought, memory, and so on as well as the animating force within the body. It is not until Descartes that the mind is ascribed with the powers of reasoning, knowledge, and emotion separate from the functioning of the rest of the body. For Descartes, the body functions independently from the mind, however the mind and body can interact to produce varying results in behavior. Although he does still discuss he mind as part of the soul, what is important is that Descartes uses and continues to develop the concept of the rational, thinking mind as being separate and distinct from the body. This mind-body distinction is obviously an important one for psychology, allowing for the development of much of physiological psychology as well as cognitive and perceptual psychology, among others.

This mind/body split led Descartes to make further conclusions about how the brain functioned. His primary concern was the workings of vision and visual perception. Descartes concluded that, based on a previously discovered “truth” that everything is in motion, light and objects give off tiny vibrations and these vibrations press upon various areas of the eye. This then causes the vibrations to move through the eye to stimulate a series of hollow nerves through which essential brain fluids flow. Much like the automata from St. Germain, Descartes envisioned that these brain fluids flowed through the nerves that were stimulated to constrict or expand by the vibrations of the objects being viewed in such a way that a sort of stamp was of what was seen was created in the brain. Reasoning that because we have two eyes but only seem to perceive any object we are viewing as singular, he further concluded that there must be a center in the brain in which the vibrations from both eyes meet to create a singular image. For Descartes, this area was the Pineal gland because it was roughly centered in the brain and not lateralized like the rest of the brain. It was also here, he concluded, that the soul resided (Fancher, 1979, chap. 1).

Although much of how Descartes reasoned the mind to work was incorrect, some of the basic ideas proved to be fundamental for future work on perception and physiological psychology. Among the important ideas are Descartes’ graphing of the visual field of perception which showed that each eye not only perceives what is directly in front of it, but also receives sense information from the outer field of the opposite eye (essentially that we see much in the left side of our visual field with our right eye and vice versa). Also, though he was wrong about the vibrations and hollow nerve tubes, he was basically correct in reasoning that there must be some center in the brain where the images from both eyes are combined into a singular image to be consciously dealt with by the mind.

It is evident that Descartes had a profound impact on ways of thinking about the world and that this impact is still seen in much of modern psychology. However, these ideas in and of themselves did little to further the cause of Psychology, for Descartes’ method of ascertaining the truth by reason alone left out an entire realm of discussion that dealt not with how the senses perceived, but what the senses perceived. Indeed, the tenets of rationalism stated that sensory information was likely to be false and unreliable and summarily dismissed it from further discussion. There was a second group of thinkers, however, who viewed sensory information and actual experiences as the only accurate measurements of and indicators of “truth.” This group was referred to as the empiricists. Compare the following basic precepts of rationalism with those of empiricism:

Basic rationalism precepts:

1. Don’t trust senses, since they sometimes deceive; and since the “knowledge” they provide is inferior (because it changes).

2. Reason alone can provide knowledge. Math is the paradigm of real knowledge.

3. There are innate ideas, e.g., Plato’s Forms, or Descartes’ concepts of self, substance, and identity.

4. The self is real and discernable through immediate intellectual intuition (cogito ergo sum).

5. Moral notions are comfortably grounded in an objective standard external to self — in God, or Forms (LaFave, 2002).

Basic empiricism precepts:

1. Senses are the primary, or only, source of knowledge of world. Psychological atomism.

2. Mathematics deals only with relations of ideas (tautologies); gives no knowledge of world.

3. No innate ideas (though Berkeley accepts Cartesian self). General or complex ideas are derived by abstraction from simple ones (conceptualism).

4. Hume — there’s no immediate intellectual intuition of self. The concept of “Self” is not supported by sensations either.

5. Hume — no sensations support the notion of necessary connections between causes and effects, or the notion that the future will resemble the past.

6. Hume — “is” does not imply “ought”. Source of morality is feeling (LaFave, 2002).

Although both of thee schools of thought believed that truth was attainable, they disagreed about the role that the senses played in discovering this truth. The rationalists employed a priori reasoning, reasoning that does not depend on experience to inform it (for example concepts and constructs such as bachelor or death that do not require certain experiences to be understood) to attain truths. The empiricists utilized a posteriori reasoning, reasoning that depends upon experience or contingent events in the world to inform it (that George Bush, Jr. is president in 2004 cannot be determined by examining the concepts of “president” and “George Bush”) for its answers (McCormick, 2001). This disagreement over which type of reasoning was superior continued until the 1780’s when Emmanuel Kant, a German philosopher, began publishing his most influential works.

Kant’s work was primarily a reaction against the work of the empiricist David Hume. He found problems with both the empiricists and the rationalists, however. Essentially Kant proposed that neither rationalism nor empiricism were sufficient, or correct, in determining absolute truths for there were truths that neither of these two schools could prove as such by only using a posteriori and a priori reasoning. Moreover, both modes of thought contained flaws that allowed two contradictory statements, or antinomies, to both be accepted as true and valid.

Kant argues that while both rationalism and empiricism assume that it is possible to obtain knowledge of how things really are, as opposed to how they seem to us, they overlook the fact that the human mind is limited. The human can experience and imagine only within certain constraints; the human mind has a hand in constructing and shaping our reality as we perceive and think about it. Specifically, these constraints are synthetic and a priori. Synthetic a priori truths, which include location in space and time, causality, experiencing self, thing-ness, and identity, do not depend on experience to be realized but also cannot be arrived at by the same kind of logical reasoning used by the rationalists. Neither of the two schools of thought was equipped to deal with these kinds of truths (McCormick, 2001).

The solution to this problem, Kant argued, was to understand that the world we experience must be distinguished into two categories—the noumenal, or external world, and the phenomenal, or internal world. The noumenal world consists of “things-in-themselves,” objects, as they exist in their pure and unfiltered form. However, Kant warns, the noumenal world can never be known directly because once it is perceived by the human mind it passes into the phenomenal world. What humans experience is not the actual world, but a re-creation, an interactive experience, of the world (Fancher, 1979, chap. 3). In this way, Kant argues that the mind is an active agent in how we perceive and interact with the world; it creates reality just as much as it perceives it.

Through this argument, Kant creates a melding of the two schools of thought—rationalism and empiricism. He verifies the methods of the empiricists in his agreement that everything that we perceive, think about, and thus know, is filtered through our senses and experience. Empiricism is complicated however, when Kant also insists that our mind creates and interprets experience and “reality” as it perceives it, and therefore rational reasoning must also be employed to ascertain a great number of truths. It is only through combining these two methods that the great majority of truths may eventually be realized.

The extensive contributions of Descartes and the rationalists provided many of the ideas and distinctions that necessarily predicated Kant’s philosophical works. Especially important was the mind/body distinction and the development of the idea that mind and body could interact with one another. Kant, by arguing that a cohesive and valid science would not be possible unless the conditions of his synthetic a priori reasoning were met, encouraged, if not forced, the melding of the rationalist and empiricist modes of thought into one that allowed for both sensory experiences and reasoning, together, to provide the basis of “truth.” However, perhaps the most important contribution to psychology is that all of this culminated in the new idea that the mind creates reality just as much as it perceives it. This idea paved the way for, indeed, created the need for a more exact study of the mind. With these new ideas in hand, and the previous obstacles to thinking removed, it would be less than a hundred years later that the first experimental psychology labs would be established and psychology would begin to flourish as a science.

References

Balz, Albert G. A. (1952). Descartes and the Modern Mind. New Haven: Yale University Press.

Descartes, René. (1960). Discourse on Method, in Discourse on Method and Meditations (Laurence J. Lafleur, Ed., and Trans.). New York: Library of Liberal Arts.

Fancher, Raymond E. (1979). Pioneers of Psychology. New York: W. W. Norton & Company.

LaFave, Sandra. (2002). Kant: The ”Copernican Revolution” in Philosophy. Retrieved February 18, 2004, from http://instruct.westvalley.edu/lafave/KANT.HTM

McCormick, Matt D. (2001). Immanuel Kant (1724-1804) Metaphysics. In The Internet Encyclopedia of Philosophy. Retrieved February 18, 2004, from http://www.utm.edu/research/iep/k/kantmeta.htm#Rationalism

Turner, Merele B. (1965). Philosophy and the Science of Behavior. New York: Appleton-Century-Crofts.