Cartesian skepticism abstracts away from all sensation but smuggles in the logic of intuition. Thus even as Descartes calls into question all claims to knowledge, even the claim that such a calling into question is itself possible, he discovers that there is only so far the skeptical moment can go before it collapses in a profound insight of pure knowledge. The Evil Genius thought-experiment is designed to topple not only any and all possible propositions but even the form of proposition itself. That is, Descartes begins from the zero-point of absolute skepticism, that is, from the perspective of what we might call the ‘perfect nihilist’. The perfect nihilist is committed to no beliefs except that it exists (not that it is alive). The only judgment the perfect nihilist is responsible for is its assertion or disposition that judgment is possible, which is premise we may call ‘the actuality of judgment’. If the nihilist is unable to make judgments, then it does not exist. It is important to recognize that the skeptical position Descartes is having us consider is effective only for beings for whom there is a distinction between seeming and being, that is, for beings who can conceive of negation. An animal, who is unable to think the difference between appearance and reality in this way is related to negation only in death. Thus, rationality is a prerequisite for both skepticism and nihilism. When someone declares “I do not exist” (as do many schizophrenics) we therefore can be certain that what they are trying to articulate is an experience lacking in properties that are otherwise inferentially nested within the concept of ‘existing’ or ‘being’ when the latter are used as predicates, for example, the feelings of ‘me-here-now’-ness and embodiment described by Patricia Churchland, or even Kundera’s unbearable lightness of being, or the nausea of existence described by Sartre. It doesn’t matter ‘what it feels like to exist’ or ‘what it’s like to be an I’ as long as its like something enough to give the I something to work with, something to notice and to judge. Some intuition. This I take to be one of Hegel’s main reasons for emphasizing the vital importance of the feeling of “fear” or “dread” trembling in “the very fibres of [one’s] being” in one’s coming to self-consciousness. Even in the case where one loses his faith in his epistemic connection towards the world, or his ability to exert his will upon it, his self-doubt can only go so far down. That is, doubt cannot pass beyond the depths of first-person awareness, which is nothing other than the presentation to the ‘I think’ of a judicable object. This object can be an ‘intelligible nothing’ so long as it yields to the form of an object in space and time. Finding the noumenon allows the rational subject to think the form of thought apart from any of its particular, passing contents. In fact, the schizophrenic’s utterance proves the plausibility of Cartesian hyper-skepticism and thus, its rightful place as the fons et origo of philosophy. There is a minimal phenomenological structure that must be in place in order for thought (not reducible to experience) of any kind to get off the ground.
What is commonly known as the Cartesian circle refers to Descartes’ deriving God by clear and distinct argument but then justifying his clear and distinct ideas by presupposing God’s existence. Thus, his conclusion justifies his starting premise and leads into a vicious circle. The notion of clear and distinct ideas refers to those ideas whose contradiction cannot be thought, that is, those whose truth requires no external justification. Logico-mathematical truths and the cogito are of course typical examples. If one understands arithmetic, its truths are indubitable. Ditto geometry. As for the cogito, Descartes points out that it is not via inference that one assents to the “je pense, donc je suis” but by realizing that insofar as there is thinking going on, I am the one doing it. This is because thinking is something that constitutes the I; it is not merely a property of a substance. In other words, thinking is teleological; it is goal directed and proceeds necessarily according to rules of inferential warrant which change the premises of each further thought as thought proceeds. Yet to do this, it must think in categories of temporal intuition. Postulating the dream allows Descartes to purify his thoughts down to their formal constitution. Revisiting Descartes is by no means a waste of time if we are interested in studying the limits of empiricism. Interestingly, what Descartes appeals to when he appeals to God’s goodness to underwrite his beliefs is functionally speaking not much different than what pragmatists like Rorty and Brandom appeal to when they appeal to the reliability of the intersubjective space of reasons to underwrite their own judicial commitments. With Descartes, Kant grounds our reason in our idea of God: “everything that thinks has a god” while the pragmatists might as well say the same though substituting “god” with “linguistic community”.
Eliminative Materialist theses which seek to reduce the cogito to an illusion of introspective transparency (or etiological anosognosia brought on by neuronal informatic neglect) are the newest avatars of Descartes’s Evil Genius thought experiment. Thus, examining books such as ‘Being-No-One’ by Thomas Metzinger and ‘Neuropath’ by R. Scott Bakker can help us think anew the scope and limits of skepticism. Our thesis will be that, reversing a phrase made by Metzinger himself, “there can be no neuroscience only neurophilosophy.”
Descartes’ skepticism is Humean and Quinean. Descartes’ asks ‘how could I know that what are clear and distinct ( a priori) ideas to me are necessarily faithful to the way the world is independent of my attempt to think it?’. In other words, Descartes’ asks how one could know that the form of thought is formally isomorphic to the structure of being. Inherent in this question (which is the nascent form of Heidegger’s question of the meaning of Being) is the notion of knowledge as thought that hits its target. Thus, implicit in the concept of knowledge is the concept of intentionality, which is the world-directedness of our thoughts occurring inside the mind to objects or states of affairs taking place outside of it. Thus, in order to draw the distinction between thinking and being, we must be able to avail ourselves of the concept of the world-in-itself and be able to apply that concept against that of the world-for-us. It is important not to overestimate what the concept of the in-itself is being used to represent. In order for us to make intelligible the possibility that the way we have determined the world in our thought (i.e., the set of predicates we’ve ascribed to it) is wrong, we need to represent the world which our thoughts are about as itself conforming to the structure of predication, albeit one harbouring different content. This will be the only way for us to acquire the ability to think the negative. Only a predicate can negate another predicate. If there is a way the world really is then there are predicates that can be fixed to it truthfully. That is, if it is possible to represent a thought as false then there must be something which it is false of. A world that can be represented incorrectly is also a world that can be represented correctly.
We may have trouble understanding why this is the case. We may believe instead that the world-in-itself might be of such a nature that it is beyond all predication, that there is no way at all to represent the in-itself with even the barest fidelity. To claim this would be to claim that the in-itself has a structure that is beyond reasoned conception. In other words, that the actual is not rational. This is the view that defines the in-itself as unthinkable as opposed to merely unknowable. This kind of hyperbolized skepticism calls into doubt not only the content of our judgments about the world (e.g., that this object is red and not green) but also the form of our judgments about the world (e.g., that there are objects with properties) in general. The in-itself is not merely an inverted world, it is not even a world. Hyperbolic skepticism asks us to consider the possibility that thinking is itself an illusion. That this is indeed what the skeptic is proposing follows from the premise, noted above, that the in-itself is here represented as bearing no relationship to the unity of judgment (or the judicable) which is a formal requirement for any predication to take place whatsoever. A world that does not bear a predicable unity therefore abides by none of the logico-mathematical laws that dictate the movements of thought which only determine the determinable. On this view, thought is its own Matrix and the mind itself is its own demon. To think that you are or ever have been thinking anything is to fool yourself. Thinking, which represents its object as existing independently of the mind, is inherently in error, not because it misrepresents its object, but because according to the first premise of such radical skepticism, there is no object and there is no representation, these both being entirely empty concepts, empty because all conception is empty. That such a position is born already contradicting itself does not faze the skeptic, for she is convinced that she has already won the argument by forcing us to entertain the necessary possibility of a world entirely alien to thought. She is not doubting the a priority of the laws according to which rational thought proceeds. These laws, she is willing to grant, may be internally consistent without at all having the power to hook onto the world-in-itself. Her point is that Truth, which is the order of thought, bears no relation to Reality, which is the order of Being. Thus, the skeptic holds onto the concept of negation in order to think the negation of all conceptuality. Thus, by interrogating the negative, we can discover the hidden premise on which the skeptic builds her argument. We will argue that thinking negation requires the ability to think time. Representing certain thoughts as true and others as false requires the ability to keep track of rules of material inference, that is, the rules of exclusive predication of one object changing in time. Failing to represent time in thought precludes the representation of negation.