According to Bertrand Russell, the phrase “theory of knowledge” has two meanings. One kind of theory, the lesser, accepts whatever knowledge science presents and seeks to account for it. Russell’s concern is with the wider kind, which embraces all problems of establishing the nature and validity of all knowledge. Confining his attention in this work to empirical knowledge, he undertakes to discover two things: (1) What is meant by “empirical evidence for the truth of a proposition”? (2) What can be inferred from the fact that there sometimes is such evidence?
Russell brings to the problem of a theory of empirical knowledge the full force of its counterpart, logical knowledge, to whose modern development he is a foremost contributor. He attacks the problems of his general task by translating their elements into formal logical symbols so as to achieve a precision lacking in the language in which the problems are usually couched. Yet the book does not consider problems of logic as such, except when they are relevant to epistemology.