First Published in 1999. The purpose of this series is to provide a contemporary assessment and history of the entire course of philosophical thought. Each book constitutes a detailed, critical introduction to the work of a philosopher of major influence and significance. Understanding a philosophical doctrine stands close to seeing its strengths and weaknesses, how best it could be defended and how best attacked. The author therefore has tried, not merely to state Russell's philosophical doctrines, but also to appraise them: to determine, if possible, whether they are true, or at least what arguments tell in their favour, and what tell against them.