Note 68 — Chapter XIX · VARIOUS POSSIBLE WORLDS

We may mention that the logicians have often endeavoured to introduce definitions of this sort into mathematics; but in mathematics, as in physics, their attempts have always been condemned. For instance, the definition of an inductive number, also given by Dr. Whitehead, was severely criticised by Poincaré (in “Science and Method”), who remarked that the object of a definition was to define, and that Whitehead’s definition being circular, defined nothing.