Bertrand Russell Speaks at University of Illinois

Daily Illini March 15, 1944

Russell Discusses Probability Theory

Noted Author to Give Second Talk Tonight

By KAY HOUSE

"What grounds have I for believing the world was existent yesterday, the sun will rise tomorrow, and there are sound waves?" questioned Bertrand Russell, noted philosopher and author, at the beginning of his talk in Lincoln hall last night.

Discussing the principles of probability and inference, Russell divided the field of probability into two kinds: that definable in terms of frequency, and that representing the degree of doubtfulness. Such organizations as insurance companies proceed on the assumption that the future will resemble the past, but the frequency theory cannot be established except by knowing the truth of each instant, and since this may not be known by mortals, frequency is not the fundamental theory of probability.

As opposed to the frequency theory in the 'degree of doubtfulness' concept, an estimate is made, and in case of two conflicting premises, the one having the smaller probability is discarded. In either of these cases, all our knowledge appears only probable though the risk of error is less in some parts of knowledge than in others.

Another lecture, applying probability to the philosophy of physics and sciences, will be given by Russell tonight. He is the author of some 70 volumes, including the famed "Principia Mathmatica ," a technical work in which he proves mathematics nothing more than logic. Many of his books have been translated into other languages, some 17 having been translated into German, for instance.

The theory of probability, according to Russell, was originally invented by mathematicians for the enlightenment of wealthy patrons who wished to know the odds in gambling. Later, it was used in the kinetic theory, the quantitative theory, and in statistics for sociology. The whole of modern science is impregnated with this concept of probability.