The Basic Works of Aristotle (Modern Library Classics) by Richard Mckeon Page A

as being the natural means by which a physical faculty is realized, but, as we have said, by convention. Yet every sentence is not a proposition; only such are propositions as have in them either truth or falsity. Thus a prayer is a sentence, but is neither true nor false.
    Let us therefore dismiss all other types of sentence but the proposition, (5) for this last concerns our present inquiry, whereas the investigation of the others belongs rather to the study of rhetoric or of poetry. 2
    5      The first class of simple propositions is the simple affirmation, the next, the simple denial; all others are only one by conjunction.
    Every proposition must contain a verb or the tense of a verb. (10) The phrase which defines the species ‘man’, if no verb in present, past, or future time be added, is not a proposition. It may be asked how the expression ‘a footed animal with two feet’ can be called single; for it is not the circumstance that the words follow in unbroken succession that effects the unity. This inquiry, however, finds its place in an investigation foreign to that before us.
    We call those propositions single which indicate a single fact, (15) or the conjunction of the parts of which results in unity: those propositions, on the other hand, are separate and many in number, which indicate many facts, or whose parts have no conjunction.
    Let us, moreover, consent to call a noun or a verb an expression only, and not a proposition, since it is not possible for a man to speak in this way when he is expressing something, in such a way as to make a statement, whether his utterance is an answer to a question or an act of his own initiation.
    To return: of propositions one kind is simple, (20) i. e. that which asserts or denies something of something, the other composite, i. e. that which is compounded of simple propositions. A simple proposition is a statement, with meaning, as to the presence of somethingin a subject or its absence, in the present, past, or future, according to the divisions of time.
    6      An affirmation is a positive assertion of something about something, (25) a denial a negative assertion.
    Now it is possible both to affirm and to deny the presence of something which is present or of something which is not, and since these same affirmations and denials are possible with reference to those times which lie outside the present, it would be possible to contradict any affirmation or denial. (30) Thus it is plain that every affirmation has an opposite denial, and similarly every denial an opposite affirmation.
    We will call such a pair of propositions a pair of contradictories. Those positive and negative propositions are said to be contradictory which have the same subject and predicate. (35) The identity of subject and of predicate must not be ‘equivocal’. Indeed there are definitive qualifications besides this, which we make to meet the casuistries of sophists.
    7      Some things are universal, others individual. By the term ‘universal’ I mean that which is of such a nature as to be predicated of many subjects, by ‘individual’ that which is not thus predicated. Thus ‘man’ is a universal, ‘Callias’ an individual. (40)
    Our propositions necessarily sometimes concern a universal subject, sometimes an individual. [17b]
    If, then, a man states a positive and a negative proposition of universal character with regard to a universal, these two propositions are ‘contrary’. By the expression ‘a proposition of universal character with regard to a universal’, (5) such propositions as ‘every man is white’, ‘no man is white’ are meant. When, on the other hand, the positive and negative propositions, though they have regard to a universal, are yet not of universal character, they will not be contrary, albeit the meaning intended is sometimes contrary. As instances of propositions made with regard to a universal, but not of universal character, we may take the