English Semantics

A traditional way of defining a sentence is ‘something that expresses a complete thought.’ This definition is a rather strange way of explaining since it assumes that we know what a complete thought is and with this knowledge can determine whether something is or is not a sentence. But surely the procedure must be the reverse. Sentences are more knowable than thoughts. In spite of individual differences speakers of a language generally agree about what is or is not a sentence in their language. Who can say what a complete thought is? Compare these language expressions:

1a We walk in the park.
1b our walk in the park
1c for us to walk in the park

We call the first a complete sentence, and in writing we begin with a capital letter and end with a period. We say the other two are not complete sentences. But all three expressions have the same semantic content, the same relation to an action or possible action performed in a certain place by two or more people, one of whom is the speaker or writer. The difference is grammatical. The first expression asserts something, makes a statement. The other two expressions can be parts of statements, as for instance:

We enjoyed our walk in the park.
It’s not too late for us to walk in the park.

but they do not make assertions by themselves. The formal differences among these three expressions—we, our and us, for example—are a matter of grammar, not semantics.

The semantic content shared by the three expressions is a proposition. A simple statement like We walk in the park expresses asingle proposition, something presented as a fact and therefore subject to verification; generally speaking, one can find out if the proposition is true or false. We don’t walk in the park is the negation of this proposition, and Do we walk in the park? is a question about it.