||The logical form of a sentence (or class of sentences) is the way the sentence is constructed out of a stock of basic vocabulary items, including a stock of distinguished logical constants (such as the familiar sentential connectives and quantifiers). A sentence's logical form determines its formal inferential relations to other sentences, and it is often thought to be important for accounting for the way the meaning of the sentence is determined by the meanings of its parts. The logical form of a sentence is not always apparent from its surface form, and there is a tradition of thinking of the logical form of a sentence as reflecting the structure of the extra-linguistic fact or state of affairs to which it corresponds. Questions about the "true" or "underlying" logical forms of some relevant class of sentences are often taken to be important for deciding issues in metaphysics and (especially) ontology. The notion of logical form is sometimes applied to propositions or mental state contents, as well as to sentences.