SINCE the inception of the International Congresses of Philosophy in 1900, it was arranged that such gatherings should be an opportunity for philosophers and men of science to meet on common ground for discussion. Nowadays, philosophers cannot claim to have a complete system unless they account for the various branches of science in their synthetic explanation of things. They must understand what men of science have found out for themselves and give a value to their discoveries in their theories of knowledge. It is quite appropriate then that they should be helped in their efforts by the searching analysis scientific workers have made of their own labours. There cannot be any antagonism between philosophy and science; one completes the other and each is strengthened by the support of the other.