Peter Hacker is the leading authority on the philosophy of Wittgenstein. He is Emeritus Fellow at St John's College, Oxford University, where he was a Tutorial Fellow in philosophy from 1966 to 2006 and he holds an honorary professorship at the Institute of Neurology, University College, London. He has held visiting chairs in North America and both British Academy and Leverhulme Senior Research Fellowships. He is the author of twenty four books and over 160 papers, and has written extensively on the philosophy of Wittgenstein, the history of analytic philosophy, philosophy of language, philosophy of mind, cognitive neuroscience, and has recently completed a tetralogy on human nature.