The Problems of Philosophy
Bertrand Russell


PREFACE

In the following pages I have confined myself in the main to those
problems of philosophy in regard to which I thought it possible to say
something positive and constructive, since merely negative criticism
seemed out of place. For this reason, theory of knowledge occupies a
larger space than metaphysics in the present volume, and some topics
much discussed by philosophers are treated very briefly, if at all.

I have derived valuable assistance from unpublished writings of
G. E. Moore and J. M. Keynes: from the former, as regards the
relations of sense-data to physical objects, and from the latter as
regards probability and induction. I have also profited greatly by
the criticisms and suggestions of Professor Gilbert Murray.

1912



CHAPTER I
APPEARANCE AND REALITY

Is there any knowledge in the world which is so certain that no
reasonable man could doubt it? This question, which at first sight
might not seem difficult, is really one of the most difficult that can
be asked. When we have realized the obstacles in the way of a