If it works for you

Lewis wrote in a time when, among the educated British public if not among their professional philosophers, there was considerably more agreement than there is now about what constitutes a valid and rational argument for a given case. Lewis might have paid more attention to Screwtape in the very first letter where Screwtape says that the time has passed in which “the humans still knew pretty well when a thing was proved and when it was not.”

Lewis’ apologetic works, “presuppose, and rarely make any argument for, the criteria for rationality.” Almost fifty years later, ‘deconstructionism’ and ‘anti-foundationalism’ have done their wasting work. Under the tutelage of today’s academy, unbelievers are skeptical about the very notion of ‘evidence,’ and they chatter cleverly about ‘plausibility structures’ and ‘paradigm shifts,’ leading them to offer the relativistic response to the most convincing of arguments: “That’s great if it works for you.” Or as it is said in England, “You are right if you think you are.”

The Second Coming of C. S. Lewis -- First Things, November 1994
Alan Jacobs (Wheaton College)