One of Berkeley's best-known arguments for the view that there are no material objects is the so-called Master Argument. There are several good critical discussions of it. That invites the question: is there anything new to say? Well, it will be argued, there are a few things to say. First, although refutations by logical analogy have been advanced against the Master Argument, the strongest such refutation, one which demonstrates its incoherence, has not been. It is here. Second, there are few formal reconstructions of the Master Argument – the great majority of discussions treat it discursively – but a formal reconstruction, and one not found elsewhere, is offered here. Third, the formal reconstruction makes possible identification of the essential mistake of the argument. That mistake is equivocation. The common complaint that Berkeley illicitly introduces the act of conceiving into the content of the concept conceived is not quite correct; but to the extent that it is correct, it's explicable in terms of an underlying equivocation. Fourth, the article presupposes no acquaintance with Berkeley's work and is written in a conversational, easy-to-read style. Given that Berkeley himself wrote in a similar style, he could at least agree that the fourth point is a merit of the article.

We can find in the passages that set out the Master Argument a precursor to the paradox of knowability. That paradox shows that if all truths are knowable, all truths are known. Similarly, Berkeley might be read as proposing that if all sensible objects are (distinctly) conceivable, then all sensible objects are conceived.