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PROPOSITIONAL ATTITUDES IN THE LOGIC OF WALTER BURLEY AND WILLIAM OCKHAM [1] While there is no separate treatise in either Burley or Ockham dealing with propositional attitudes, there are a considerable number ofpassages in the logical writings ofeach ofthe two authors which do in fact deal with propositional attitudes. As may be expected, many of these passages are found in the discussions of modal logic in general , while some appear in other contexts, in particular in those places in which the question of supposition of terms is raised, or in the context ofdiscussion of general inferential relations involving the so-called non-standard (i.e. epistemic and doxastic) modes, or in the theory of formal disputation. [2] By 'propositional attitude' I mean locutions such as 'a knows that p,' 'a believes that p,' 'a doubts that p,' and so on, and their counterparts in the passive voice, presumably equivalent in their logical force to those in the active voice; e.g., 'p is known,' 'p is believed,' 'p is doubted,' and so on. [3] These latter ways offorming such attitudinal claims are much more frequent in both Burley and Ockham than their counterparts in the active voice. Both authors, at least occasionally formulate such claims in an expanded form, e.g., 'p is known by you' or 'p is known by me,' and I shall understand this to be a sufficent indication that Burley and Ockham at least half-consciously assumed an epistemic subject , even though their tendency to use an impersonal passive mode may have prevented them from fully realizing the sui generis character of the epistemic/doxastic logic which they were in fact helping to develop. [4] The study of propositional attitudes constitutes what has be- 32IVAN ??? come known as epistemic or epistemic/doxastic logic.1 In order to be logic, such an enterprise must consider relations among propositions such as compatibility or consistency, inconsistency, implication or entailment , and the like; in order for it to be epistemic/doxastic logic, such an enterprise must consider the logical relations precisely as these are present in virtue of propositional-attitude-functors such as 'is known by a,' 'is believed by a,' etc. [5] Although nowadays epistemic/doxastic logics are sometimes presented as deductive calculi, the late-medievals (as well as the rediscoverers of the discipline in our own century, e.g., J. Hintikka, R. Chisholm and a great many philosophers of recent decades), thought of this enterprise primarily as a critical examination of our ordinary, natural-language uses.2 Thus, if there are cases of natural uses wherein we seem to allow locutions such as 'p, but I don't believe it,' we have to take such cases seriously and then decide whether our current statements of necessary and sufficient condition for knowledge should continue to include the claim that if I know that p, then I must believe that p. [6] The full-fledged developments of epistemic logic seem to have taken place in England during the second quarter of the fourteenth century. As far as we know at this stage of research, the leaders in those development appear to have been William Heytesbury (d.1372/3) [and other Oxford Fellows Richard Kilvington (d. 1361), John Dumbleton (fl. 1340s), Richard Swineshead (fl.1340-55), Ralph Strode (d.1387)] and the distinguished "followers" of the English tradition in 1 In our own century, epistemic/doxastic logic was rediscovered and systematically investigated by Jaakko Hintikka in his Knowledge and Belief (Ithaca &t London: Cornell Univ. Press, 1962). Within the framework of this logic, an especially influential article was that by Edmund L.Gettier, "Is Justified True Belief Knowledge?" Analysis, 23 (1963): 121-23. 2 Cf. Wolfgang Lenzen, Recent Work in Epistemic Logic, Acta Philosophica Fennica, vol. 30, issue 1 (Amsterdam: North-Holland Publishing Co., 1978). In this comprehensive study Professor Lenzen examines many arguments the structure and components of which amply illustrate the reliance of the proponents on our natural language uses. For medievals, the Latin language was of course not natural in exactly the same sense, but even though it was a learnt "scientific" language, it was not an artificial language in the sense in which our schematic and axiomatic languages...

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