In Probability and Evidence Ayer also criticised the frequency interpretation of probability, noting that under this interpretation the probability of an event will change with any change in the reference class to which that event is assigned. The frequency interpretation itself cannot determine whether the choice of one reference class over another is better for the determination of the relevant probability, and so suffers from a critical defect if it is to be of any use in solving problems associated with inductive inference. (For further discussion of Ayer’s views on probability and induction see Bela Juhos 1969, and Foster 1985, pp.198–227.)