 Causation. Causation is dealt with in several of Broad’s works (beginning as early as his first book, Perception, Physics and Reality, 1914). The logic of conditions formulated in (1930b) would square well with some version of the regularity theory of causation. However, in several works rather penetrating criticism of that theory is offered (e.g., in Ch. 3, 1925). In (1933) he tries to formulate an alternative. Causality involves something between regularity and logical entailment; there is some form of necessity, but not the kind involved in logical entailment. The latter is an absolute necessity. Consider the proposition ’Anything that has shape would have extension’. This is not only true in the actual world: it is true in all logically possible worlds; there could not have been a world in which there were things that had shape but lacked extension. Now compare the proposition ’Anything that had inertial mass would have gravitational mass’. There could not be things in the actual world which had inertial mass but lacked gravitational mass. But there could have been a world in which there were things that had inertial mass but lacked gravitational mass. The kind of necessity involved here is a contingent necessity. (Cf. 1933, pp. 242–3.) Broad is, however, rather skeptical of the alternative he has sought to formulate. He says with characteristic candor that the notion of a necessity which is contingent might very well be “sheer nonsense”.