ABSTRACT
Sentences may be interrogative, optative, exclamatory, or imperative; they may also be indicative. Throughout most of the remainder of our discussions, we may confine ourselves to indicative sentences, since these alone are true or false. In addition to being true or false, indicative sentences have two other properties which are of interest to us, and which they share with other sentences. The first of these is that they are composed of words, and have a meaning derivative from that of the words that they contain; the second is that they have a certain kind of unity, in virtue of which they are capable of properties not possessed by their constituent words.
