The main theme of this book is Wittgenstein’s later diagnosis of the confusion underlying the picture theory of the proposition. This leads to a re-interpretation of Wittgenstein’s method of philosophy in
Philosophical Investigations. Wittgenstein’s method is diagnostic to an extent that has not been realized, and thus not clarified. Wittgenstein’s practice of dissolving a philosophical problem, by showing how that problem arises, is much more predominant than most realize.