Perfect Science and the Knowability Paradox

In The Limits of Science [5], N. Rescher embraces a logical argument known as the Knowability Paradox, according to which, if every true proposition is knowable, then every true proposition is known, i.e., if there are unknown truths, there are unknowable truths. Rescher argues that the paradox, providing evidence of a limit of our knowledge (the existence of unknowable truths), could be used for arguing against perfected science. In this article, we present two criticisms of Rescher’s argument. The first one points out that Rescher is ambiguous on the meaning of “impossibility of a perfected science”: it could be interpreted in at least two different ways, one of which is plainly unproblematic compared with the Knowability Paradox. In the second criticism, we argue that the kind of unknowability involved in the paradox is semantic, rather than epistemic. Therefore, it is not a real problem for science. The final conclusion of the paper is, if our criticisms are correct, that the paradox leaves open the possibility of a perfected science. The paper is divided into three parts. In the first one, we give an account of the paradox and our reading of Rescher’s argument. In the second and third parts, we point out our criticisms. If our arguments are correct, Rescher’s conclusion, according to which the Knowability Paradox constitutes a problem for perfected science, is mistaken