This triangle of cogito, religion, and madness is the focus of the polemic between Foucault and Derrida, in which they both share the key underlying premise: that the cogito is inherently related to madness. The difference is that,
for Foucault, the cogito is grounded in the exclusion of madness,
for Derrida, the cogito itself can only emerge through a “mad” hyperbole (universalized doubt), and remains marked by this excess: before it stabilizes itself as res cogitans, the self-transparent thinking substance, the cogito explodes as a crazy punctual excess. 328
Foucault
Foucault’s starting point is a fundamental change in the status of madness which took place in the passage from the Renaissance to the classical Age of Reason (the beginning of the seventeenth century). During the Renaissance (Cervantes, Shakespeare, Erasmus, etc.), madness was a specific phenomenon of the human spirit which belonged to the series of prophets, possessed visionaries, saints, clowns, those obsessed by demons, and so on. It was a meaningful phenomenon with a truth of its own: even if madmen were vilified, they were treated with awe, as if messengers of a sacred horror.
With Descartes, however, madness is excluded; in all its varieties, it comes to occupy a position that was formerly the preserve of leprosy. It is no longer a phenomenon to be interpreted, its meaning searched for, but a simple illness to be treated under the well-regulated laws of a medicine or a science that is already sure of itself, sure that it cannot be mad.
This change concerns not only theory, but social practice itself: from the Classical Age on, madmen were interned, imprisoned in psychiatric hospitals, deprived of the full dignity of a human being, studied and controlled like a natural phenomenon.
Derrida
Through a detailed analysis, he tries to demonstrate that, far from excluding madness, Descartes pushes it to an extreme: universal doubt, where I suspect that the entire world is an illusion, is the greatest madness imaginable. Out of this universal doubt the cogito emerges: even if everything is an illusion, I can still be sure that I think. Madness is thus not excluded by the cogito: it is not that the cogito is not mad, but the cogito is true even if I am totally mad. Extreme doubt, the hypothesis of universal madness, is not external to philosophy, but strictly internal to it, a hyperbolic moment, the moment of madness, which grounds philosophy. Of course, Descartes later “domesticates” this radical excess with his image of man as a thinking substance, dominated by reason; he constructs a philosophy which is clearly historically conditioned. But the excess, the hyperbole of universal madness, is not itself historical; it is the excessive moment which grounds philosophy in all its historical forms. Madness is thus not excluded by philosophy: it is internal to it. Of course, every philosophy tries to control this excess, to repress it―but in repressing it, it represses its own innermost foundation: “Philosophy is perhaps the reassurance given against the anguish of being mad at the point of greatest proximity to madness.
Žižek
… the true point of “madness,” which is not the pure excess of the “night of the world,” but the madness of the passage to the symbolic itself, of imposing a symbolic order onto the chaos of the Real. If madness is constitutive, then every system of meaning is minimally paranoid, “mad.” Recall again … the lesson of David Lynch’s Straight Story: what is the ridiculously pathetic perversity of figures like Bobby Peru in Wild at Heart or Frank in Blue Velvet compared to deciding to cross the US central plane on a lawnmower to visit a dying relative? Measured against this act, Frank’s and Bobby’s outbreaks of rage are but the impotent theatrics of old and sedate conservatives. In the same way, we should say: what is the mere madness caused by the loss of reason compared to the madness of reason itself?
This dark core of madness at the heart of the cogito can also be determined in a more genetic way…. A naked man is the same nonsense as a shaved ape: without language (and tools and …), man is a crippled animal ― it is this lack which is supplemented by symbolic institutions and tools, … How do we pass from the “natural” to the “symbolic” environment?
This passage is not direct, one cannot account for it within a continuous evolutionary narrative: something has to intervene between the two, a kind of “vanishing mediator,” which is neither Nature nor Culture―this in-between is not the spark of logos magically conferred on homo sapiens, enabling him to form his supplementary virtual symbolic environment, but precisely something which, although it is also no longer nature, is not yet logos, and has to be “repressed” by logos ― the Freudian name for this in-between is, of course, the death drive. 334
Upon a closer look, it becomes evident that, for Kant, discipline and education do not directly work on our animal nature, forging it into human individuality: as Kant points out, animals cannot be properly educated, since their behavior is already predestined by their instincts. What this means is that, paradoxically, in order to be educated into freedom (qua moral autonomy and self-responsibility), I already have to be free in a sense much more radical, “noumenal,” monstrous even. The Freudian name for this monstrous freedom is, again, the death drive.
It is interesting to note how philosophical narratives of the “birth of man” are always compelled to presuppose a moment in human (pre)history when (what will become) man is no longer a mere animal but also not yet a “being of language,” bound by symbolic Law; a moment of thoroughly “perverted,” “denaturalized,” “derailed” nature which is not yet culture.
In his anthropological writings, Kant emphasized that the human animal needs disciplinary pressure in order to tame that uncanny “unruliness” which seems to be inherent to human nature―a wild, unconstrained propensity to insist stubbornly on one’s own will, whatever the cost.
It is on account of this that the human animal needs a Master to discipline him: discipline targets this “unruliness,” not the animal nature in man.
In Hegel’s Lectures on Philosophy of History, a similar role is played by the reference to “negroes”: significantly, Hegel deals with “negroes” before history proper (which starts with ancient China), in the section entitled “The Natural Context or the Geographical Basis of World History”: “negroes” here stand for the human spirit in its “state of nature,” they are described as a kind of perverted, monstrous children, simultaneously naïve and corrupted, living in a pre-lapsarian state of innocence, and, precisely as such, the cruelest of barbarians; part of nature and yet thoroughly denaturalized; ruthlessly manipulating nature through primitive sorcery, yet simultaneously terrified by raging natural forces; mindlessly brave cowards. 338-339