Philosophical Investigations

Wittgenstein died in 1951 without publishing it, and it appeared in 1953, edited by G. E. M. Anscombe and Rush Rhees with Anscombe's English translation. The first part, numbered remarks 1 to 693, was the portion he regarded as close to ready. The second part, originally called Part II and later titled Philosophy of Psychology: A Fragment in the fourth edition, consists of later material that he had not integrated. The fourth edition, edited by P. M. S. Hacker and Joachim Schulte in 2009, revised the text and translation, and scholars now cite which edition they use because remark numbering and wording differ.

The book opens with a passage from Augustine describing how a child learns words by being shown objects, and Wittgenstein treats it as an expression of a primitive picture in which words name things and sentences combine names. He argues that the picture fits only a narrow range of uses and ignores the many different functions words have. Through the builders' game and other examples, he shows that naming already presupposes a practice within which naming makes sense. The picture also underlies the Tractatus, which makes the opening a self-critique as well as an attack on a tradition.

Wittgenstein asks what makes it the case that someone applies a rule correctly, and argues that no interpretation can fix its own application, since any interpretation can be reinterpreted. He concludes that following a rule is a practice, not an act of interpreting. Saul Kripke's Wittgenstein on Rules and Private Language, published in 1982, read this as a skeptical paradox answered by a community-based solution. Critics including Gordon Baker and Peter Hacker, and later John McDowell, rejected Kripke's reading as a misrepresentation, arguing that Wittgenstein's target is a mistaken picture of understanding, not meaning itself.

In the remarks on a private language, Wittgenstein considers whether someone could keep a diary naming a private sensation with a sign, defined only by inner concentration. He argues that there would be no criterion distinguishing correct from merely seeming-correct use, so the sign would not have meaning. The argument is taken to undermine Cartesian pictures of inner objects known only to their owner. Interpreters disagree about its scope and about whether it denies the privacy of experience or only a particular theory of how we name it. Commentators such as Norman Malcolm and Anthony Kenny offer differing readings.

Using the example of games, he argues that no single feature is common to everything we call a game, and that the term holds together through overlapping similarities, like the resemblances among members of a family. This challenges the assumption, found in the Tractatus and in much earlier philosophy, that a general term must pick out an essence. The notion has been influential in cognitive science, in prototype theory associated with Eleanor Rosch, and in aesthetics. Critics have asked whether family resemblance can explain why some cases are excluded, and Wittgenstein's remarks leave that question open.

A common misreading holds that Wittgenstein defends relativism or behaviorism, so that meaning is whatever people do or inner life does not exist. He rejects both: the book treats rules as constraints within shared practice and insists that denying a particular picture of inner states is not denying the states. Another misreading takes the slogan that meaning is use as a crisp definition, when he presents it as a corrective for particular cases. Because the text proceeds through examples and questions without announcing doctrines, quoting single remarks as theses risks distorting its method.