So internalized is the representational view that one can forget that it didn’t have to be this way. The history of psychology is, like all histories, full of contingencies and precipitous forks in the road. In the study of the history of Western philosophy we call the 17th and 18th centuries the “Early Modern” period, and the contemporary idea that we live in our heads, experiencing only a mental representation of the world, dates from this period. It was an incredibly fertile period for European philosophy: if we take, as most do, Descartes to be the first canonical Early Modern philosopher and Kant to be the last, the whole period is a scant 154 years (from the publication of The Discourse on Method in 1637 to the publication of The Critique of Pure Reason in 1781).
The adjective “Cartesian” literally means that an argument or position reflects the ideas of Descartes, but it has become through usage a more general term that alludes to representational theories of mind, particularly those theories that entail that we must worry about the relationship between the external world and a perceiving subject’s representation of the world – theories that “explain” perception as the formation of representations. This is not entirely fair to Descartes, who wrote in his Dioptics that it would be a mistake to take the inverted image observable on the retina as evidence that there were pictures in the mind, “as if there were yet other eyes in our brain.”
Even if the real Descartes was not someone who today we would call a Cartesian, he can certainly be held responsible in large part for the conspicuous lack of naturalism about psychology in modern philosophy: he was a metaphysical dualist, he thought that humans’ rational capacity comes not from nature but from God (notoriously he made this argument after arguing that he could prove God’s existence through the exercise of rationality), and he was a human exceptionalist who took language as evidence that humans are essentially different from the rest of the natural world. But the real “Cartesian” in the sense of the true ancestor of modern representational theory is Kant.
Kant’s explicit project was to block the naturalization of psychology. He was alarmed by what he saw as the atheistic, amoralist implications of Hume’s empiricism (implications emphasized by Hume himself). Hume’s whole oeuvre can be read as a sustained attack on the very idea of rationality: there are no “rational” proofs of anything, no “rational” reason for believing in anything. Beliefs are the product of “habituation,” the conditioning effect of regularities of experience. Thus there was no basis, on Hume’s view, for asserting the existence of God, of human freedom, or even of the human mind if by that was meant something over and above the contents (the “impressions”) of thought processes, which were the products of experience. Kant seems to have been intuitively certain that these radical conclusions were false, although he was criticized (by Nietzsche for example) for a programmatic development of foreordained conclusions.
Hume’s psychology was inadequate. Like Locke before him he thought that mental content could be naturalized if it was explained as the result of a physical process of perception: interaction with the environment was the physical cause of the impression, a physical effect. This strategy led the empiricists to emphasize a rejection of innate content, which they regarded as a bit of bad rationalist metaphysics. The problem was compounded by a failure to distinguish between innate content and innate cognitive ability. To some extent this failure reflected a desire to strip psychology down to the simplest perception/learning theory possible in the interest of scientific method, coupled with a lack of Darwinian ideas that can provide naturalistic explanations of innate traits (I will address the skeptical, “phenomenalist” reading of Hume, that I think is incorrect, in Chapter Three).
Kant saw this weakness and was inspired to develop the argument of the Critique of Pure Reason. Hume claimed that all knowledge was the result of experience. Kant’s reply was to ask, “What is necessary in order for experience to be possible?” The greatness of Kant is in his effort to backwards-engineer the mind. He is best read today as a cognitive scientist. However people forget how radical Kant’s conclusions were, and how influential they have continued to be, one way or another, to virtually all philosophers and psychologists since the late 18th century. From the persuasive argument that the mind must somehow sort and organize the perceptual input (that’s the part of psychology that the empiricists’ ideology led them to neglect), Kant goes on to argue that space, time, cause and effect relations and the multiplicity of objects are all part of the “sensible” frame that the mind imposes on our experience of the world. The world of our experience is the phenomenal world, and it is that world that is the subject of natural science; the world-in-itself is the noumenal world (and quite the bizarre, Parmenidean world it is!).
Two points are important here. First, Kant’s aim was to protect human psychology (and religion and ethics) from a godless, amoral, reductive natural science and in that he succeeded to an alarming extent. The world of natural science on the Kantian view is the world as it is conceived by the rational mind, and as such the rational mind itself cannot be contained in it. Second, Kant’s biggest contribution of all is easy to miss precisely because it is so basic to his whole line of argument: the phenomenal world is a representation, made possible by the framing structure of rational conception, just as the drawing on the Etch-a-Sketch depends on the plastic case, the internal mechanism and the knobs of the toy.
The defender of Kant will argue that the Kantian phenomenal world is not a representation at all: it is the world presented to us in a certain way. It is also only fair to point out that Kant, unlike his modern descendents, shared with Plato the view that all rational minds were identical to the extent that they were rational. Kant would not have been amused by 20th century philosophers’ pictures of a world where each language, culture and individual were straying off, like bits some expanding universe, into their private “conceptual schemes,” ne’er the twain to meet. Nonetheless Kant needs mental representation (and any conceptual schemata is representational), because he needs to protect freedom, rationality, God and ethics. Thus a deep skepticism is intentionally built in to Kant’s system (as it is not in Descartes’). While Kant is right in a great many things and any student of philosophy or psychology must read and understand him, on these two points his influence is ultimately pernicious.
I dilate on the Kantian history of the representational theory because once we see that the issues that confront us in philosophy of mind continue to be essentially metaphysical we also see that they are very old issues, and ones that connect up with many other perennial philosophical problems. Too many people in contemporary philosophy of mind and cognitive science fail to appreciate this and the discussion is very much the poorer for that. Furthermore it’s important to see that things didn’t have to be this way. The idea that we are stuck in our heads with our “representation” of the world forever mediating between us and “reality” is actually a very strange idea, but it has been so deeply internalized by so many that we can fail to appreciate how strange it is. This is something to bear in mind as we think about how modern physicalist philosophy of mind has struggled with the problem of mental representation.