Introduction 1. Truth and necessity in mathematics 2. The thesis that mathematics is logic 3. Mathematics without foundations 4. What is mathematical truth? 5. Philosophy of physics 6. An examination of Grünbaum's philosophy of geometry 7. A philosopher looks at quantum mechanics 8. Discussion: comments on comments on comments: a reply to Margenau and Wigner 9. Three-valued logic 10. The logic of quantum mechanics 11. Time and physical geometry 12. Memo on 'conventionalism' 13. What theories are not 14. Craig's theorem 15. It ain't necessarily so 16. The 'corroboration' of theories 17. 'Degree of confirmation' and inductive logic 18. Probability and confirmation 19. On properties 20. Philosophy of logic Bibliography Index.