Philosophy must distinguish sharply between absolute truth and absolute knowledge of that truth. Whereas the former concept serves as the crucial regulative principle for any rational worldview, the latter concept negates rationality itself. Any philosophy that denies the existence of absolute truth also denies the existence of error, and thereby repudiates any possibility of error correction: that is, of rational criticism and progress. And yet a similar problem arises for any philosophy that, in addition to guarding the concept of absolute truth, endorses the concept of absolute knowledge of absolute truth. For such a philosophy denies human fallibility, thereby denying again the possibility of human error and hence of error correction. So, it is critical that we regard absolute truth and absolute knowledge of absolute truth as fundamentally distinct concepts. Rationality can survive only if we accept one while rejecting the other, for to either accept or reject both concepts together would negate the concept of error correction, without which the higher-level concepts of reason and progress would become meaningless.