If the concept of probability and the formulae of the theory of probability are used without a clear understanding of the collectives involved, one m… - Richard von Mises

Mass phenomena to which the theory of probability does not apply are, of course, of common occurrence.

Apart from this older generation, there is scarcely a modern mathematician who still adheres without reservation to the classical theory of probability. The majority have more or less accepted the frequency definition.

I do not want to defend the occult sciences; I am, however, convinced that further unbiased investigation of these phenomena by collection and evaluation of old and new evidence, in the usual scientific manner, will lead us sooner or later to the discovery of new and important relations of which we have as yet no knowledge, but which are natural phenomena in the usual sense.