Propositions

Different sentences can carry the same meaning, as in (1.12a–c).

Proposition is the term for a kind of core sentence meaning, the abstract idea that remains the same in cases such as (1.12a–c). Propositions in this technical sense are very abstract, not tied to particular words or sentences: the proposition carried by (1.12a, b) can be expressed without using the verb hunt, as shown in (1.12c). A young child who is unsure about which are seals and which are sharks could, while watching a (somewhat gory) nature program, point at sharks and seals, respectively, for the two occurrences of these in (1.12d) and, without using any of the words in (1.12a–c), bring the same proposition into play.

The only feature that all propositions have – and this is a litmus test for propositions – is that it is reasonable to wonder whether they are true or false. I am not saying that anybody need be well enough informed to know for certain whether or not a given proposition is true, just that propositions are, in principle, either true or false. I have been told that the proposition in (1.12a–c) is true. I think it is, but notice that we have to know what is being spoken or written about before we can judge whether a proposition is true or false. The proposition expressed by a sentence is not known until an explicature has been worked out for it: reference and ambiguities both cleared up using contextual information. The explicatures for generic sentences such (1.12a–c) are relatively easy to get at: something like ‘for all typical sharks and all typical seals, when they are engaging in typical behavior, the former hunt the latter’. That is why I presented generic sentences to start with. But with (1.12d) you would need to know what is referred to by “These” and “these others” before it becomes sensible to ask whether it is true, and that is going to require information about the particular context in which an utterance based on the sentence is used.

The sentences in (1.12) are declaratives, the sentence pattern on which statements (utterances that explicitly convey factual information) are based. Once they have been explicated, it is easy to see that they express propositions, because reactions such as the following can reasonably be made to them: “Yes, that’s true” or “That’s a lie” or “Is that really true?” Utterances based on some other sentence patterns cannot comfortably be reacted to like this. Try imaginary conversations in which such responses are made to examples like those in (1.13) (for example: A “What’s your name?” B “That’s a lie.”).

Even though most conceivable explicatures of the sentences in (1.13) would not express propositions, they nonetheless involve propositions. The question in (1.13a) carries a proposition with a gap ‘addressee’s name is ___’ and cooperative addressees supply their name to fill the gap. The request (1.13b) presents a proposition ‘addressee help sender’ and the sender hopes that the addressee will act to make that proposition come true.

Ambiguities are another reason for needing the concept of propositions. Example (1.14) can express, at least, two different propositions because right is ambiguous: ‘correct’ or ‘right-hand’.