 It is, for instance, possible to say that a chicken believes a certain sort of caterpillar to be poisonous, and mean by that merely that it abstains from eating such caterpillars on account of unpleasant experiences connected with them. The mental factors in such a belief would be parts of the chicken’s behaviour…  Thus any set of actions for whose utility \(p\) is a necessary and sufficient condition might be called a belief that \(p\)…  (1927a, [FM] 144)