Keywords: Metaphysical Analicity; A Priori; Ayer; Boghossian.
In "Language, Truth and Logic" Ayer explicitly defends the notion of analyticity that is nowadays discussed under the label, introduced by P. Boghossian, of «metaphysical analyticity». According to Ayer, this notion of analyticity is key to defending the empiricist principle that all knowledge of reality stems from and is justified by experience from the objection that some propositions are known a priori. In this paper I argue for two negative claims. The first claim is that even if all a priori knowledge were knowledge of metaphysical analyticities, it would still not follow that it is not knowledge about reality. The second claim is that Ayer's metaphysical analyticity is not a property that any sentence could intelligibly instantiate.