A CAUSAL CALCULUS (I)*

Tins paper contains a suggested quantitative explication of probabilistic causality in terms of physical probability.1 The main result is to show that, starting from very reasonable desiderata, there is a unique meaning, up to a continuous increasing transformation, that can be attached to ' the tendency of one event to cause another one '. A reasonable explicatum will also be suggested for the degree to which one event caused another one. It may be possible to find other reasonable explicata for tendency to cause, but, if so, the assumptions made here will have to be changed. I believe that the first clear-cut application in science will be to the foundations of statistics, such as to an improved understanding of the function of randormsation, but I am content for the present to regard the work as contributing to the philosophy of science, and especially to what may be called the ' mathematics of philosophy '. Light may also be shed on problems of allocating blame and credit. I hope to consider applications to statistics on another occasion.2 In a previous note 3 I have tried to give an interpretation of 'an event F caused another event E ' without making reference to time. It was presumably clear from the last three paragraphs, which were added in