The protagonists of post-Enlightenment relativism and perspectivism claim that if the Enlightenment conceptions of truth and rationality cannot be sustained, theirs is the only possible alternative.

Post-Enlightenment relativism and perspectivism are thus the negative counterpart of the Enlightenment, its inverted mirror-image. Where the Enlightenment invoked the arguments of Kant or Bentham, such post-Enlightenment theorists invoke Nietzsche’s attacks upon Kant and Bentham. It is therefore not surprising that what was invisible to the thinkers of the Enlightenment should be equally invisible to those post-modernist relativists and perspectivists who take themselves to be the enemies of the Enlightenment, while in fact being to a large and unacknowledged degree its heirs.

Alasdair MacIntyre, Whose Justice? Which Rationality?