‘The Unity of the Proposition’ is a label for a problem which has intermittently intrigued philosophers but which for much of the last century lay neglected in the sad, lightless room under the stairs of philosophical progress, along with other casualties and bugaboos of early analytic philosophy such as the doctrine of internal relations, the identity theory of truth, and Harold Joachim. Yet it was while struggling with this problem (among others), that Bertrand Russell built one of the first steps on the staircase by creating what came later to be called the theory of descriptions.1 According to that theory, statements containing definite descriptions are true only if there exists a unique thing satisfying the description. So nothing one says about ‘The Problem of the Unity of the Proposition’, for example, can be true unless there is one and only one such problem. Yet, as we shall explain below (§1), on the one hand it is unclear that there is any such problem at all, while, on the other, if there is a problem, there seem to be several. One might conclude, then, that everything we say in this paper is likely to be false. But perhaps the paper could be, in the context, appropriately treated as a ladder, to be kicked away after climbing. For Wittgenstein, too, was concerned with the problem: ‘At the centre of Wittgenstein’s project was the task of explaining the unity of the proposition’, says Michael Potter, for example.2 Wittgenstein had inherited the task from two of his philosophical mentors, Russell and Frege. Yet while Russell’s series of failed accounts of propositions, and then judgments, each of which was meant to resolve the problem, seemed ultimately to serve only as a sort of negative inspiration for him,3 Frege’s response to the problem proved a deep influence. We will outline Frege’s position as a backdrop to Wittgenstein’s below (§§2 and 3). As we will argue, one of the most important ways in which Wittgenstein’s position resembles Frege’s is precisely that his (Wittgenstein’s) solution to the problem of unity required treating his own book as an attempt to say the unsayable...