The Problems of Philosophy is a 1912 book by the philosopher Bertrand Russell, in which the author attempts to create a brief and accessible guide to the problems of philosophy. He introduces philosophy as a repeating series of attempts to answer the same questions: Can we prove that there is an external world? Can we prove cause and effect? Can we validate any of our generalizations? Can we objectively justify morality? He asserts that philosophy cannot answer any of these questions and that any value of philosophy must lie elsewhere than in offering proofs to these questions. Wittgenstein suggested further that these questions are empty and the value of philosophy is as an assistant to science.Focusing on problems he believes will provoke positive and constructive discussion, Russell concentrates on knowledge rather than metaphysics: If it is uncertain that external objects exist, how can we then have knowledge of them but by probability. There is no reason to doubt the existence of external objects simply because of sense data.