P. M. S. Hacker is the leading authority on the philosophy of Wittgenstein. He is author of the four-volume Analytical Commentary on the Philosophical Investigations (1980-96), the first two volumes co-authored with G.P. Baker, and of the epilogue Wittgenstein’s Place in Twentieth Century Analytic Philosophy (Blackwell, 1996). He has written extensively on philosophy and neuroscience--Philosophical Foundations of Neuroscience (Blackwell, 2003) and History of Cognitive Neuroscience (Wiley Blackwell, 2008), both co-authored with M.R. Bennett. He has published three volumes of a tetralogy on human nature: Human Nature: The Categorial Framework (Blackwell, 2007), The Intellectual Powers: A Study of Human Nature (Wiley Blackwell, 2013), and The Passions: A Study of Human Nature (Wiley Blackwell, 2018). He is currently completing the final volume - The Moral Powers: A Study of Human Nature (forthcoming). Together with Joachim Schulte, he has produced the fourth edition and extensively revised translation of Wittgenstein’s Philosophical Investigations (Wiley Blackwell, 2009). They are currently working on a new edition and translation of Wittgenstein’s On Certainty.