Immediately upon its posthumous publication in 1953, Ludwig Wittgenstein's Philosophical Investigations was hailed as a masterpiece, and the ensuing years have confirmed this initial assessment. Today it is widely acknowledged to be the single most important philosophical work of the twentieth century.
In this definitive new en face German-English edition, Wittgenstein experts Peter Hacker and Joachim Schulte have incorporated significant editorial changes to earlier editions of Philosophical Investigations in order to reflect more closely Wittgenstein's original intentions. Notable revisions include the placement of Wittgenstein's notes - Randbemerkungen - into their designated positions in the text, some corrections to the originally published German text, and the numbering of all the remarks in what was Part 2 and is now named Philosophy of Psychology - A Fragment. Extensive modifications and corrections have also been made to G. E. M. Anscombe's original English translation. Detailed editorial endnotes have been added to illuminate difficult translation decisions and to identify references and allusions in Wittgenstein's original text.

Peter Hacker is the author of the four-volume Analytical Commentary on the Philosophical Investigations (Blackwell, 1980-96) the first two volumes co-authored with G. P. Baker (Second Editions, 2003, 2009) and of Wittgenstein’s Place in Twentieth-century Analytic Philosophy (Blackwell, 1996). He has also written extensively on philosophy of mind, including Philosophical Foundations of Neuroscience (Blackwell, 2003) and History of Cognitive Neuroscience (Wiley-Blackwell, 2008), co-authored with M. R. Bennett, and Human Nature: The Categorial Framework (Blackwell, 2007), the first volume of a trilogy on human nature.

Joachim Schulte edited the authoritative critical-genetic edition of Wittgenstein’s Philosophische Untersuchungen (2001). He is author of  Wittgenstein: An Introduction (1989), Chor und Gesetz: Wittgenstein im Kontext (1990), Experience and Expression: Wittgenstein’s Philosophy of Psychology (1993), and of many dozens of philosophical papers.