Some care is needed in using Descartes' argument. "I think, therefore I am" says rather more than is strictly certain. It might seem as though we are quite sure of being the same person to-day as we were yesterday, and this is no doubt true in some sense. But the real Self is as hard to arrive at as the real table, and does not seem to have that absolute, convincing certainty that belongs to particular experiences.

In 1896 he taught German social democracy at the London School of Economics where he also lectured on the science of power in the autumn of 1937. However his books were sold at auction to raise the money. He was a member of the Advisory Council of the British Humanist Association and President of Cardiff Humanists until his death.

Bertrand Arthur William Russell 3rd Earl Russell OM FRS (18 May 1872 – 2 February 1970) was a British philosopher logician mathematician historian and social critic. Whitehead Principia Mathematica an attempt to ground mathematics on logic. ".