1. The present paper was read, in various stages of development, to seminars at Stanford University, Cornell University and the Universities of Massachusetts, Lancaster and Durham. I am indebted to those who took part in those discussions, and to my fellow symposiasts at Helsinki, for much valuable criticism and stimulation. In particular I am indebted to Professors Stalnaker, Aune and Kanger and to Dr. P. J. Fitz-Patrick.
2. The line of thought explored in this first section was suggested by corresponding explorations of von Wright in the area of deontic logic. Over the years von Wright has wavered between reading a formula of deontic logic such as ‘Op’ as ‘one ought to do p’ and reading it as ‘it ought to be the case that p’. (See, for instance, ‘Deontic Logic Revisited’, Rechtstheorie 1973, p. 37). A way of reading ‘Op’ which he sometimes adopts is ‘it is obligatory to see to it that p’ (An Essay in Deontic Logic and the General Theory of Action, Amsterdam 1968, p. 37). My suggestion here is in the same spirit; but I prefer the expression ‘bring it about that p’ because ‘bring it about that’ does not carry the suggestion of intentionality, of purposively bringing it about that p, which to my ear’ see to it that p’ does.
3. Here I am indebted to Dr. P. J. FitzPatrick.
4. “He can speak Spanish or Portuguese” as Prof. A. Brod has pointed out to me, may mean “Either he can speak Spanish, or he can speak Portuguese; I don’t know which”.
5. For the distinctions used in the table, see F. R. Palmer, A Linguistic Study of the English Verb (London 1965); B. Aune, article ‘Can’ in The Encyclopedia of Philosophy; J. L. Austin, ‘Ifs and Cans’ in Philosophical Papers (Oxford 1961); P. Nowell-Smith, ‘Ifs and Cans’, Theoria 26 (1960) 85-101; M. R. Ayers, The Refutation of Determinism (London 1968); R. Gibbs, ‘Real Possibility’, American Philosophical Quarterly 7(1970) 340-348; A. M. Honoré, ‘Can and Can’t’, Mind 73 (1964) 463-479; J. P. Snyder, Modal Logic and Its Applications (New York 1971) and G. H. von Wright, An Essay on Modal Logic (Amsterdam 1951).