P.M.S. Hacker is the leading authority on the philosophy of Wittgenstein. He has also written extensively on philosophy of neuroscience and philosophy of language. He is Emeritus Research Fellow at St John's College, Oxford and holds an Honorary Professorship at University College London's Institute of Neurology. He has held both British Academy and Leverhulme Senior Research Fellowships and visiting chairs in North America. He is author of more than twenty books and over 160 papers, including the preceding three volumes in the Human Nature tetralogy: Human Nature (2007), The Intellectual Powers (2013), and The Passions (2018).