The Cartesian Paradigm

Lecture 12.  October 2 and 8.

Afterthoughts.  I talked about a Cartesian Paradigm, or Framework, that would guide scientific psychology for much of the twentieth century.  Here I want to amplify two aspects of the paradigm that will be especially important and trouble-making as we move through the rest of the course.

The first aspect is Descartes’ consideration of the mind-body problem and his particular solution to it, interactive dualism.  Most people share an intuition that there is something unique about people that sets us off from things and from the other animals, and we have seen how the Greek philosophers articulated this intuition in different ways.  However, Cartesian dualism is different from Greek dualisms, especially Aristotle’s, in important ways, and I want to stress here how Descartes’ situation is different from Aristotle’s (or all premodern thinkers) not so much because of his conception of mind or soul, but because of the new conception of matter as machine ushered in by the Scientific Revolution.

The key distinction for Descartes is between the soul and the machine-body, but for Aristotle (and the Bronze Age Greeks, too) the key distinction to be drawn was between the living and the nonliving.  For Aristotle, soul was the presence of life, in plants, animals, and humans alike.  The soul was not a thing apart from the living body, but defined the essence of each kind of creature, animated it, and gave it purpose: Soul was form, body was matter.  Soul was life-process, and what distinguished each grade of soul were the processes unique to it: animals had sensation and movement, to which humans added the ability to formulate universal truths.

Descartes, however, had to jettison the idea that plants and animals had souls, because in Christian thought only humans have souls, and he came to regard all physical things, including plant, animal, and human bodies, as machines whose various movements could be explained in the same mechanical terms as the movements of a clock or of the new Newtonian clock-universe.  For Aristotle on the one side there was unformed, unanimated matter and on the other was defining, change-giving form, or soul; for Descartes, on one side were machines, capable of motions of their own, having mechanical causes, and on the other was disembodied nonphysical soul.  Animal behavior had mechanical causes, as seemed clear from Vaucanson’s Duck and other clever automata.  Most importantly, animals had internal cognitive-mechanical processes too, responsible for sensation, awareness, imagination, memory, and learning, things traditionally associated with soul.  But for Descartes, these were no longer life-processes of the soul, as for Aristotle, but mechanical processes of the presumed reflexive gears, springs, and wheels of the nervous system and brain.  Soul was limited to one arena, consciousness, and found in only kind of creature, human beings.

The second critical aspect of the Cartesian Paradigm was the creation of the private realm of consciousness that flowed from the new scientific withdrawal of soul from the material world.  Ideas existed in consciousness only (and animals did not and could not) have them.  Because there seemed to be a New World of consciousness, it invited exploration and study with a special tool for making the voyage, introspection.  Thus was created the idea of a science devoted to consciousness, psyche-logos, the science of the soul.

Forethoughts.  We will soon see the problems raised by this new definition of human science; indeed, we have already met one in Princess Elizabeth’s observations about the difficulties of claiming that a machine can act on spirit and spirit on a machine, the problem of interaction.  What I want to point out here is a more basic problem for psychology defined according to the Cartesian framework: It makes doing psychology as a science nearly impossible, especially as science, especially physiology advances, and as the enterprise of science itself becomes more precisely formed in the nineteenth century.  

So little is left to soul in the Cartesian view that it will become tempting to simply eliminate the concept altogether and say that men are machines as are all animals, albeit more complicated ones.  If one takes this step, then since there is no psyche there can be no psyche-logos anymore then there can be Zeus-logos.  

On the other hand, if one retains the idea of consciousness, other problems arise.  If consciousness is real, but does not interact with body (the view of psycho-physical parallelism we’ll soon meet), then one can have a disciplined study of consciousness, but its point becomes unclear, especially when science is linked to application.  If consciousness exists but does not do anything, its study can have little, if any, practical pay-off.  In addition, introspection is necessarily a private exploration of one person’s consciousness, and even if it’s done in a lab with the best intentions and the tightest methodological controls, the resulting data are tainted with subjectivity, including the possibility of individual differences, the powers of suggestion and expectation, and the difficulties of verifying the accuracy of introspective reports.  While disputes of course arise in any science over the validity of data, the data of introspection will seem especially dodgy, and the enterprise of psyche-logos, while logically possible, will seem to many not to be worth the effort.

Note that these problems would not have arisen for an Aristotelean psyche-logos, because in Aristotle there is no private world of non-physical ideas populating a non-physical soul.  There is, of course, experience in Aristotle’s psychology, but experience is the process of sensation and perception; it is not the collective set of ideas present at some moment in consciousness.  There are no ideas needing description and reduction to lawful order.

That is why my last slide on Descartes said that while he invited the creation of psyche-logos, he made its practice impossible, even paradoxical.


Psyche and Psychology

Lecture 4.  September 2 and 8.

Afterthoughts.  The deepest problems of biology and psychology began with explaining the difference between the living and the non-living by positing the existence of an entity, the psyche, that inhabits the bodies of living creatures.  In biology, this line of thought led to vitalism, the idea that living tissue possesses a vital “spark of life” making it absolutely and decisively different from mere matter.  In psychology (note we still call our field after the breath of life), it leads to the problem of dualism.  It is clear that animals and people are material beings in some sense like rocks–drop me and a rock off of a tall building and we both break.  And it is also clear that animals and people are different — I move sense the world and respond to it, the rock does not.  The problem arises when we explain the difference by saying I (or an animal) possess a secret thing inside, a psyche,  responsible for my sensing and behavior.  If the psyche is a thing, rather than a process, we immediately want to know what it looks like, how it works, how it controls the body, whether it can exist without a body, and so on, and these questions become the subject matter of psyche-logos, the study of the soul.  But suppose that there is no such thing?  Can there be a science about nothing?

Forethoughts.  The problems posed by dualism will be important in understanding Plato and Aristotle. Plato will follow Pythagoras and accept the idea that the soul can exist without the body, that it ought to exist without the body, and, going past the Bronze Age definition of psyche as a breath of life, hold that the soul is the essence of each individual person, and that all, not just a few, are eternal.  This point of view will help give Plato’s philosophy its rather religious, otherworldly, and puritanical cast: The Good is not to be found in this life but in heaven (Plato’s upward hand in Raphael’s painting).  Aristotle, on the other hand, will to a large degree accept the Bronze Age collection of mini-souls, but will resist the notion that souls are things, preferring to see them as life-processes rather than as indwelling entities.  Moreover, Aristotle does not see the body as a dangerous tomb wherein the soul is stored between happy existences in heaven, but as the proper and necessary condition of living a full life (Aristotle’s downward gesture in The School of Athens).  Aristotle’s psychology could have avoided the problems that will plague dualism (and psychology) well into the twentieth century, but, as we will learn, dualism trumps naturalism in the history of psychology.

Evolution of Psychological Systems: What is science?


During its short formal history, psychology has proclaimed itself to be a science, though this claim has sometimes been disputed (as we’ll see) and what goes after the intro text definition “Psychology is the science of ….” has changed.  However, it’s rarely the case (outside Division 24 types) that psychologists tackle the question of what science is and how it works.  There’s a huge literature on this (it’s called philosophy of science), but as Thomas Kuhn observed about sciences in general, scientists consult this literature only during periods of doubt and crisis.  This literature is the focus of the first 2 weeks’ classes, though I try to tame it by focussing on one important question: What is scientific explanation? Thus we also will ask, can psychology give scientific explanations of the same type given in other sciences?  Should it?

Afterthoughts on class of August 21.  On our first day, I took up the question of scientific explanation, and covered the most traditional way of treating it, associated with positivism and logical positivism. The positivist movement is of great importance in philosophy of science, because it basically created the field.  Positivists saw science as a uniquely (in the strong sense) successful human institution, and strove to distill the essence of science into a content-free set of methods that could be applied to any topic whatsoever, from the movements of the planets to the question of god’s existence.  As it did so, positivism began to influence the practice of science, especially those sciences, such as psychology, that were uncertain of their status as sciences (we’ll get to this historical part later).

Positivists proposed a very precise definition of scientific explanation, the deductive-nomological model, that I covered in the first lecture.  Critical to the the D-N model are these ideas: laws of nature, explanation as deduction, and explanation as prediction.

Forethoughts.  In the next class, we will consider criticisms of the D-N model and alternatives to it, most importantly the causal approach and the semantic conception of theories.  One thing to do before class is to think about the term “model” as you have encountered it in psychology and the use of the term “model” in the economics paper I have asked you to read.  Of course, that paper’s authors are writing for fellow economists, so their definition is implicit (though, as we’ll see, closer to the formal meaning in philosophy of science) and thus hard to grasp.  But I hope the exercise in encountering a mysterious, even alien, scientific, culture, will help in achieving one of my major goals for the course: Seeing psychology from the outside.