What makes communication by language possible?

1. What makes communication by language possible? “What makes the task [of understanding others] practicable at all is the structure the normative character of thought, desire, speech, and action imposes on … interpretation of .. speech and explanations of … actions” {Davidson, 1990}.

2. A sentence is an arrangement of words constructed according to the syntax of a language. Sentences are absract objects that do not have locations or other concrete properties. An utterance is an event with a time and place; utterances have can be short or long, soft or harsh. A proposition is something that can be true or false; and propositions have their truth values essentially. Sentences are the things which are uttered, and propositions are the things utterances express. What do you utter? Sentences. What do utterances express? Propositions.

3. Different utterances of a single sentence can express different propositions. Example: “It is raining today” utterances of different sentences express the same proposition, e.g., “It will rain tomorrow” [uttered on Tuesday] “It is raining today” [uttered on Wednesday] “It was raining yesterday” [uttered on Thursday]

4. Striking fact (a) If someone utters a sentence and you know which proposition her utterance expresses, then it’s likely that you will also understand which propositions other utterances of the same sentences express. Conversely, if you don’t understand one utterance of a sentence, it is likely that you won’t understand other utterances of it either. Portability. Sentences enable us to communicate in ways that, to a very large extent, are independent of context and background knowledge. Re-usability. Sentences can be re-used on different occasions and by different people to communicate the same information.

5. Hypothesis 1 Sentences have meanings. Users of a language know the meanings of sentences in that language. Knowing the meaning of a sentence someone utters enables one to know which propositions her utterance expresses. Each sentence has an X. Users of a language know the X of sentences in that language. Knowing the X of a sentence someone utters enables one to know which propositions her utterance expresses. The meaning of a sentence is whatever property knowledge of which enables us to know which propositions utterances of that sentence express.

6. Striking fact (b) Linguistic abilities are systematic—someone who understands an utterance of “Leo ate John” can probably also understand an utterance of “John ate Leo” Systematicity “there are definite and predictable patterns among the sentences we understand. For example, anyone who understands ‘The rug is under the chair’ can understand ‘The chair is under the rug’” {Szabó 2004}. Striking fact (c) Linguistic abilities are productive—we can understand utterances of an indefinitely large range of sentences we have never heard before. Example: “John ate Leo who ate Ayesha who ate …” Productivity we can understand utterances of an indefinitely large range of sentences we have never heard before.

7. Hypothesis 2 (i) Languages are compositional: that is, sentences are composed of words arranged according to syntactic rules, and the meaning of a sentence is determined by the meanings of its constituent words and their arrangement (ii) We know the meanings of words and the rules governing how they can be arranged into sentences. This enables us to know the meanings of sentences.

8. If Hypothesis 2 is correct, we can explain productivity. Consider an utterance of the novel sentence “Leo ate John who ate Ayesha.” According to Hypothesis 2, 1. we know the meanings of the individual words of this sentence and the rules of composition; and 2. the meanings of the individual words together with rules of composition determine the meaning of the sentence uttered And from Hypothesis 1: 3. Knowing the meaning of the sentence enables us to understand the meaning of the utterance In this way, Hypothesis 2 explains productivity.

9. We now have a pair of functional characterisations: • meaning of a sentence: whatever it is knowledge of which enables language users to understand utterances of that sentence (that is, to know which proposition the utterer expresses) • meaning of a word: whatever it is knowledge of which, together with knowledge of rules for composition, enables language users to know the meanings of sentences containing the word.