No principle has enjoyed more abject fealty in the annals of Western philosophy than the principle of contradiction. From Aristotle onward, almost all philosophers have invoked this hallowed principle to support their philosophical systems or to embolden skepticism of them all. Whether identified in Aristotle's formulation or in Kant's revision, the principle of contradiction has yielded the same outcome: reason's search for truth has been banished from the territory in which contradiction is encountered.

For Aristotle, there are no regrets. The principle of contradiction is the fundamental first principle of reason and only on its basis can philosophy achieve any positive results. For Sextus Empiricus, our refuge from dogmatic philosophy depends upon it. The principle of contradiction is the implicit foundation of his ancient skepticism, which can thereupon confidently suspend judgment whenever argument can be shown to fall into contradiction. For Kant, the principle of contradiction is the guarantor of both logical coherence and metaphysical restraint. Although the principle provides certainty of consistency, rather than truth, it saves us from following our natural inclinations to think the unconditioned and pretend that we could attain truth through reason.

Only Hegel calls into question acceptance of the allegedly irrefutable principle of contradiction. He suspects that any skepticism that depends upon it is not skeptical enough, whereas any philosophical system that pays it homage cannot possibly be valid.

Aristotle on Contradiction

The fateful embrace of the principle of contradiction finds its classic expression in Aristotle, who turns to it tellingly in pursuit of a first principle of reason. To know truth without qualification, Aristotle acknowledges, philosophy must be the freest, most sovereign discipline. Instead of being captive to any particular condition or perspective, philosophy must uncover what is most universal and fundamental, for nothing can be comprehended in truth unless that without which nothing can be or be known is grasped. To overcome bondage to given phenomenon and given standpoints, philosophy must uncover that which is presuppositionless, that which is by nature rather than by convention, that which is immediate rather than mediated by some contingent condition. What is immediate can serve as an ultimate foundation for being and knowing provided it not only rests on nothing else but is that from which all else emerges and can be intelligible.