Wittgenstein is famous for revolutionizing philosophy not once but twice. He claimed to have solved all the problems of philosophy in his Tractatus Logico-Philosophicus, only to return to philosophy ten years later, repudiate many of the central claims of Tractatus Logico-Philosophicus, and reinvent philosophy a second time with the Philosophical Investigations.

Among the central differences between the earlier Wittgenstein of Tractatus Logico-Philosophicus and the later Wittgenstein of the Philosophical Investigations and his various notebook writings is a shift in emphasis regarding the importance of logic. In Tractatus Logico-Philosophicus, logic is given central importance as determining the structure of language and reality, but it receives scarcely a mention in the Philosophical Investigations.

Wittgenstein’s later philosophy abandons the rigidly structured world of Tractatus Logico-Philosophicusin favor of a less pristine and more modest conception of a complex world that resists any simple articulation. While the differences between the earlier and later philosophies of Wittgenstein go deep, significant similarities remain.

The four Core Ideas that follow trace some of the most important points on which Wittgenstein’s position does not change radically throughout his career.

Popular pages: Selected Works of Ludwig Wittgenstein