We’ve been talking about the law of non-contradiction (LNC), which says that the statements p and not-p cannot both be true. (In symbolic notation: ~ (p • ~p) ) We briefly noted Aristotle’s view that skepticism about LNC cannot be made a coherent position. Let’s now consider a famous remark on the subject by the Islamic philosopher Avicenna or Ibn Sina (c. 970-1037). In The Metaphysics of the Healing, he says of such a skeptic:
As for the obstinate, he must be plunged into fire, since fire and non-fire are identical. Let him be beaten, since suffering and not suffering are the same. Let him be deprived of food and drink, since eating and drinking are identical to abstaining. (Quoted in the SEP article “Contradiction”)
Is this merely an expression of frustration with the skeptic? Or is there an argument here? Not quite either, I think. The use of “must” and “since” indicates that Avicenna does suppose that inflicting such pain on the skeptic should convince him of the error of his ways even if nothing else does. Hence there is more here than just a desire to punish the obstinate skeptic. Avicenna seems to think the pain should correct him. But it can’t be that Avicenna supposes that his remark amounts to a further argument for LNC. That the defender of LNC holds that fire is not the same as non-fire, suffering not the same as not suffering, etc. is something the skeptic already knows. These examples by themselves don’t add anything argumentation-wise to less harrowing examples that will no doubt already have been presented to the skeptic (e.g. that something can’t be both a cat and a non-cat, can’t both be a carrot and not be a carrot, and so on).
Obviously there is something about the unpleasant nature of the specific examples Avicenna uses that is supposed to be doing the work – and in particular, something about actually inflicting this unpleasantness on the skeptic that would do the work, rather than merely having him tranquilly contemplate the thesis that fire is not non-fire.
What is going on, I suggest, is that Avicenna takes the defect in the skeptic to lie in the will, not in the intellect. It is not that the skeptic’s intellect needs further argumentation in order for him to see that his position is mistaken. All the necessary argumentation is already present; in particular, all a properly functioning intellect should need to know is that denying LNC is simply incoherent. Rather, the skeptic is being willful – pretending, as it were, that there is really some serious doubt about LNC when in fact there is none. And his will accomplishes this by not allowing the intellect to dwell on the incoherence, thereby facilitating its focusing instead on the fact that we can say things like “Perhaps LNC is not true,” as if this expressed a real possibility rather than mere verbiage.
Literally thrusting the skeptic into the fire, Avicenna is (I suggest) saying, would nullify the will’s distraction of the intellect, and force the intellect to see reality. Under intense pain it could no longer maintain the pretense that the fire it feels might at that same moment and in the same sense be non-fire.
Another way to put it is that what the skeptic needs is not rational argumentation, since his delusional position of its very nature makes him incapable, while he is entertaining it, of listening to reason. Rather, what the skeptic needs is a kind of treatment or therapy – indeed, something like shock therapy to bring him back to reality and cease clinging to his foolish and merely verbal quibbles.