‘Grass is red’ is the only premise and is obviously false, so (X) should convince you that there are arguments with merely obviously false premises. On the face of it, there is nothing irrational about being so convinced by (X). But then (X) is a rationally persuasive argument with merely obviously false premises.

A cheap trick you say? Not so, say I — a trick yes, but, I shall argue, far from cheap. In ‘ ‘P, Therefore, P’ Without Circularity,’ Roy Sorensen uses numerous examples like these to suggest, among other things, that there is a missing parameter to argument evaluation, viz. exemplification. I shall argue, however, that understanding these sorts of cases in the way that motivates Sorensen to recommend adding the extra parameter has extremely unpalatable consequences. I shall propose an alternative account that avoids these consequences.