ABSTRACT
IT is quite possible to develop the mathematical theory of probability and also the logical foundations of this theory without giving much attention to the definition of "probability"; different definitions may cause slight modifications in the development but nothing fundamental. This does not mean that all definitions are equivalent but that the development is not fully rigorous. The importance of finding the correct definition is partly theoretical, but it also bears on the scope of probability. A prime condition that the definition must obey is that it shall be compatible with the mathematical theory and its logical foundations.
