Although Descartes’s cogito is created as a concept, it has presuppositions. This is not in the way that one concept presupposes others (for example, “man” presupposes “animal” and “rational”); the presuppositions here are implicit, subjective, and preconceptual, forming an image of thought: everyone knows what thinking means. Everyone can think; everyone wants the truth. Are these the only two elements—-the concept and the plane of immanence or image of thought that will be occupied by concepts of the same group (the cogito and other concepts that can be connected to it)? Is there something else, in Desc-artes’s case, other than the created cogito and the presupposed image of thought? Actually there is something else, somewhat mysterious, that appears from time to time or that shows through and seems to have a hazy existence halfway between concept and preconceptual plane, passing from one to the other. In the present case it is the Idiot: it is the Idiot who says “I” and sets up the cogito but who also has the subjective presuppositions or lays out the plane. The idiot is the private thinker, in contrast to the public teacher (the schoolman): the teacher refers constantly to taught concepts (man—rational animal), whereas the private thinker forms a concept with innate forces that everyone possesses on their own account by right (“I think”). Here is a very strange type of persona who wants to think, and who thinks for himself, by the “natural light.” The idiot is a conceptual persona. The question “Are there precursors of the cogito?” can be made more precise. Where does the persona of the idiot come from, and how does it appear? Is it in a Christian atmosphere, but in reaction against the “scholastic” organization of Christianity and the authoritarian organization of the church? Can traces of this persona already be found in Saint Augustine? Is Nicholas of Cusa the one who accords the idiot full status as conceptual persona? This would be why he is close to the cogito but still unable to crystallize it as a concept. In any case, the history of philosophy must go through these personae, through their changes according to planes and through their variety according to concepts. Philosophy constantly brings conceptual personae to life; it gives life to them.
The idiot will reappear in another age, in a different context that is still Christian, but Russian now. In becoming a Slav, the idiot is still the singular individual or private thinker, but with a different singularity. It is Chestov who finds in Dostoyevski the power of a new opposition between private thinker and public teacher. The old idiot wanted indubitable truths at which he could arrive by himself: in the meantime he would doubt everything, even that 3 + 2 = 5; he would doubt every truth of Nature. The new idiot has no wish for indubitable truths; he will never be “resigned” to the fact that 3 + 2 = 5 and wills the absurd—this is not the same image of thought. The old idiot wanted truth, but the new idiot wants to turn the absurd into the highest power of thought—in other words, to create. The old idiot wanted to be accountable only to reason, but the new idiot, (loser to Job than to Socrates, wants account to be taken of “every victim of History”—these are not the same concepts. The new idiot will never accept the truths of History. The old idiot wanted, by himself, to account for what was or was not comprehensible, what was or was not rational, what was lost or saved; but the new idiot wants the lost, the incomprehensible, and the absurd to be restored to him. This is most certainly not the same persona; a mutation has taken place. And yet a slender thread links the two idiots, as if the first had to lose reason so that the second rediscovers what the other, in winning it, had lost in advance: Descartes goes mad in Russia?
Deleuze G., Guattari F. What is Philosophy? NY, 1994. P. 61-63.