Propositions, Propositional Attitudes and Belief Revision.
Rohit Parikh · 1998
In this paper I will propose a new approach to certain semantic puzzles due to Frege, Kripke and others, and the question of propositional attitudes, via the notion of belief revision. The principal logical tool used for setting up the solution is the notion an individual theory. I shall suppose that each individual has his or her own theory consisting of the sentences the individual accepts. It is this theory, which together with the individual’s preferences leads to a choice of some actions over others; it is this theory out of which the individual communicates; and it is this theory which is revised when a communication, in the form of a sentence uttered by another, is heard or otherwise received. The theory may also be revised as a result of an experience with the “world ” as might happen when someone without an umbrella gets wet and adds “It is raining ” to his theory. There is also a community theory Tc which consists of sentences which we all accept and which, in the varous puzzles, has a different notion of possibility from that of the individual’s theory. Thus there is conflict between these two theories not only about what is true or what is known, but even about what is possible. It turns out that most of the puzzles considered in the literature are puzzles about reconciling these two theories. A crucial aspect of this way of looking at the puzzles is that the central role of truth conditions as the determinants of meaning is rejected and more flexible, purely syntactic tools are used. It will be argued that the truth theoretic view of meaning is not an adquate tool for semantics, and abandoning it makes the problems much more amenable. This need not imply abandoning truth, but merely dethroning it from its central role as a foundation for semantics.