In this paper, I examine the grammatical nature of Wittgenstein's private language argument (PLA). On my interpretation, the definition of private language implies that the private speaker has no natural expressions for his sensations. This in turn implies that he has no criterion of correctness for using his sensation‐words. This then implies, together with the grammatical rule that a word is senseless without a criterion of correctness for its use, that private sensation‐words are senseless, and hence also that private language (...) is senseless. So in my analysis, Wittgenstein succeeds in dissolving the problem of private language through a grammatical investigation, and therefore, his treatment of private language is consistent with his metaphilosophy. I further explain that Wittgenstein provides a diagnosis of the error of the philosopher who thinks that private language is possible and that he also offers a therapy consisting of analogies or objects of comparison. I also make a comparison with previous studies on the PLA and discuss a number of novelties in my interpretation. (shrink)