This fourth and final volume of the monumental commentary on Wittgenstein's Philosophical Investigations covers pp 428-693 of the book. Like the previous volumes, it consists of philosophical essays and exegesis.

P. M. S. Hacker is Fellow of St. John's College, Oxford. He is author of Insight and Iffusion (1972, revised ed. 1986), Appearance and Reality (Blackwell, 1987) and Wittgenstein: Meaning and Mind (Blackwell, 1990). He edited The Renaissance of Gravure: The Art of S. W. Hayter (1988), Graure and Grace: the Engravings of Roger Vieillard (1993) and co-edited a Festschrift for H. L. A. Hart together with J. Raz. Law, Morality and Society (1977). He has written five books with G. P. Baker, Wittgenstein: Understanding and Meaning (Blackwell, 1980), Wittgenstein: Rules, Grammar and Necessity (Blackwell, 1985), Frege: Logical Excavations (Blackwell and Oxford University Press, New York, 1984), Language, Sense and Nonsense (Blackwell, 1984), and Scepticism, Rules and Language, (Blackwell, 1984).