Page 310 - Encyclopedia of Philosophy of Language

Language and Logic
information (including misinformation), and prop- ositions are taken to be the principal values of all the various currencies of information.
The theoretical status of propositions can be seen in at least two ways. First, propositions might be considered theoretical posits: entities which one believes in precisely because they explain talk of what people say, believe, hope, and so on, and because they explain central features of the processes of com- munication and psychological inference. If this is right, then empirical facts about the use of prop- ositional attitude sentences (see Sect. 6 below) and about communication and inference, will count as data to which a theory of propositions must be adequate—it is an empirical task to discover what propositions are. Second, propositions might be thought of as theoretical constructs which allow the organization and unification of theoretical explana- tions of the various semantic, mental, and other phenomena. Seen in this way, one is oneself in control of what propositions are; what is open to empirical question is rather their theoretical utility.
2. Propositions, Sentences, Meanings, Facts
Since it is possible to say the same things with different words, and even in different languages, the things people say, propositions, are not simply the sentences they utter; nor, clearly, are they the utterances them- selves (statements, in the case of assertion). Neither are propositions the meanings of sentences: the sen- tence 'I am hungry' has just one meaning when you and I utter it, but you express a proposition about yourself, and I do not. The relationship seems to be this: a statement consists of a speaker assertively utter- ing a sentence with a certain meaning, thereby express- ing a certain proposition, and taking on a commitment to its truth. Other forms of utterance, includingques- tions and commands, involve propositions in parallel ways.
Propositions often are distinguished not only from sentences and statements, but also from facts and states of affairs. A proposition might be true or false, whereas facts can only exist, and states of affairs can either be the case (alternatively: hold, be factual) or not. These distinctions are important only in certain theories, like situation semantics, which make use of more than one of these kinds of entity.
Propositions and truth conditions are at the very least intimately related. A proposition is an abstract claim that things are a certain way. Truth conditions (of a statement, sentence, proposition, or whatever) are simply the conditions that must hold if the thing under consideration is to be true. The conditions that must hold and the abstract claim that they do in fact hold are difficult to tell apart, so many theorists stipu- late that propositions simply are their truth con- ditions, and are as well the truth conditions of statements, beliefs, and so on. Others havepreferred
to hold that propositions have their truth conditions essentially, but are not identical to them.
Even among the philosophers and linguists who agree that propositions ought to play a crucial theor- etical role, there is little agreement about precisely whattheyare.Amongthemanydifferent conceptions of proposition relevant to the study of language, the most prominent include Frege's 'thoughts' (based on Platonic universal entities he calls 'senses'), Russell's 'structured propositions' (whichcontain concrete ob-
jects as well as universals; this conception is explained well in Soames 1987), and Carnap's 'intensions' (based on the notion of a complete description of the world in an ideal language). Refined versions of Carnap's conception survive in theories of possible worlds (Lewis 1986; Stalnaker 1984) and in early situ- ation theory (Barwise and Perry 1983). One's choice of a particular conception of proposition should be motivated by considerations about what kinds of en- tities are suited to the roles propositions play, and how they must be individuated (distinguished from one another).
3. Individuating Propositions
It is usually agreed that if propositions are to be bear- ers of truth and objects of attitudes like belief, then simply by the indiscernibility of identicals, it follows that they must be individuable by a truth test and by a belief test: if/? is true (or might have been true) and q is false (or might then have been false), then p and q cannot be the same proposition; if p is an object of belief for an agent and q is not, then p and q cannot be the same proposition. These tests, it may seem, can provide data to be explained by a theory of what propositions are.
3.1 Talking about Propositions
As important and as legitimate as these tests are, how- ever, their application in any particular case is by no means straightforward, largely because of difficulties concerning the logical form of devices for talking about propositions, and accompanying difficulties in securely hanging on to p and q from the premises to the conclusions of the tests. For instance, one might have thought it clear that, since Tom can believe the proposition that Cicero was an orator while not believing the proposition that Tully was an orator, then the proposition that Cicero was an orator must be different from the proposition that Tully was an orator, in spite of the fact that Cicero is the same person as Tully. But even given the truth of the prem- ises about Tom's beliefs (for some philosophers doubt that these premises can possibly be true), the con- clusion follows only if one assumes (a) that the belief reports used in the premises have a very straight- forward logical form (say, reporting simply that the belief-relation holds between Tom and a specified
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