page 152 note * Printed in the Mathematical Gazette, July, 1922.

page 153 note * I do not know whether Mr. Keynes has considered and rejected a definition of irrelevaance which, prima facie, would be simpler then his. He does not state definitely whether every pair of propositions has some probability-relation, but I think he does not hold this view. I think he would say, e.g. that there is no probability-relation between the propositions “ 2+2= 4 ” and “ Napoleon disliked poodles ” If so, it would seem natural to define h as irrelevant to a when a/h does not exist.

page 158 note * I take this opportunity to protest against Mr. Keynes’'s practice of alluding to Principia Mathematics as though I were the sole author. Dr. Whitehead had an equal share in the work, and there is hardly a page in the three volumes which can be attributed to either of us singly.