It is both desirable and plausible to treat natural language itself as a "knowledge representation (KR) formalism. Every KR formalism has syntax and support certain inferences. The syntax of a KR formalism specifies the form in which knowledge must be encoded, and its inference mechanism depends on its syntax. If natural language is a formalism for representing knowledge, then its syntax provides specifications of well-formed formulae. In addition, reasoning must be done directly on the basis of syntax, as in any artificial KR scheme. In this respect, existing syntactic theories are inadequate, because syntax in these theories does not support reasoning. In this paper I present a new conception of the syntax, semantics, and inference mechanism of natural language. The central ideas are (1) that word use determines the forms of sentences, and (2) that these forms are used to express meaning and perform inference. Syntax, semantics, and inference are seen as an integrated whole, rather than separate and autonomous fields as in many existing studies of natural language.