The question of the content of the book was more difficult. There is a vast range of topics which could be discussed under the heading of ‘philosophy of psychology’, and a great many different approaches to those topics could be taken. For scientific psychology is itself a very broad church, ranging from various forms of cognitive psychology, through artificial
intelligence, social psychology, behavioural psychology, comparative psychology, neuro-psychology, psycho-pathology, and so on. And the philosopher of psychology might then take a variety of different approaches, ranging from one which engages with, and tries to contribute to, psychological debates (compare the way in which philosophers of physics may propose solutions to the hidden-variable problem); through an approach which attempts to tease out philosophical problems as they arise within psychology (compare the famous ‘under-labourer’ conception of the role of the philosopher of science); to an approach which focuses on problems which are raised for philosophy by the results and methods of psychology.