Among modal claims, claims that involve the notions of broadly logical possibility and necessity, one that seems almost trivial is this: that if some proposition is possible, then it is possibly true. However, there is an argument, due in its essentials to the medieval philosopher and logician Jean Buridan, to the effect that this seemingly trivial claim is, in fact, untrue. ;Briefly put, the argument is this. Let Q be the proposition that Quine does not exist. Since Quine's existence is (...) contingent, Q is possible. But, propositions are ontologically dependent upon their constituents, and Quine is a constituent of Q. So, necessarily, were Quine not to exist, neither would Q exist. And, a necessary condition of a proposition's being true is that it exist. Hence, there are propositions, such as Q, that are possible, but not possibly true. I call this conclusion, together with certain other similar claims, 'Buridanism'. ;My main topic is the evaluation of the argument for Buridanism, and the exploration of the consequences of Buridanism for modalist theories of possible worlds and for modal logic. I begin by examining the two crucial premises in the argument for Buridanism: N-dependency, according to which propositions expressed by sentences containing proper names are singular propositions that depend ontologically upon the referents of those names, and Buridan's Thesis, according to which a proposition can be neither necessary, nor possible, nor true, unless it exists. ;Robert Adams has argued that accepting Buridanism forces us to revise the modalist conception of possible worlds as maximal and consistent propositions or sets of propositions. I show that this is not the case, and provide an analysis of a proposition's being true relative to a world that allows us to maintain the modalist account while embracing Buridanism. ;Standard systems of quantified modal logic are prone to several related problems that I refer to as the problems of contingency. These systems often include as theorems formulas that seem to presuppose that everything that exists, exists necessarily. I develop a system of modal logic, BML, based upon Buridanism, that is able to overcome these difficulties. (shrink)

In spite of alleged differences in purpose, descriptive and computational linguistics share many problems, due to the fact that any precise study on language needs some form of knowledge representation. This constraint is mostly apparent when interpretation of sentences takes into account elements of the so-called “context”. The parametrization of context, i.e. the explicit listing of features relevant to some intepretation task, is difficult because it requires flexible formal structures for understanding or simulating inferential behaviour, as well as a large (...) amount of information about conventional structures in the given language. This paper aims at illustrating major difficulties in these two fields, in relation with the necessity of a contextual approach. It offers a (clearly partial) enumeration of open problems inthe reperesentation of commonsense knowledge and languages-dependent structures, with some attempt to delineate future solutions. (shrink)