'ground' why it is what it is. As such they are logically 'prior' to the conclusion, forming as they do the indispensable presupposition of the conclusions reached in science.[1]
To understand more fully the nature of the premises from which the necessary truths of science are deduced, there are certain terms which must be defined, (1) When a proposition is said to be true 'without exception' (κατὰ παντός), we mean that it is true of every member of a class, and of every member of that class at all times. Thus, if it is true that "every man is an animal," it is also true that every person who can be called "man," may also be called "animal"; and if at any given moment he is the one, he must also at the same time be the other. (2) By 'essential' (καθ' αὑτό) it is meant that a certain element is included in the very conception or definition of a thing. Aristotle distinguishes two cases in which this principle holds good; for either a certain property is 'essential' to the definition of the subject, or the subject to the definition of the property. We cannot define a 'line' without including the 'point,' and we cannot define 'straight' without including the 'line.' Again, when a property is predicated of an individual, it is said to be predicated 'essentially' whereas a property which is not predicated of an individual, but of something which presupposes an individual, is said to be predicated 'accidentally.' In the judgment, "Socrates walks," the predicate belongs to the subject; but in the judgment, "the white walks," the predicate does not belong to the subject, but to something else not expressed—ultimately, an individual. In the one case we have 'essential' predication, in the other 'accidental.' Lastly, that is said to be 'essential' which involves a causal connection; as, e. g., when a victim dies by the stroke of the sacrificial knife. These two last cases do not satisfy the requirements of strict science. The former only yields judgments which predicate a property of the individual, and from singular judgments no universal conclusion, such as science demands, can be derived. The latter, again, only gives us judgments which are conditionally necessary, whereas strictly scientific judgments are true at all times. Thus, as Aristotle himself
- ↑ Post. Anal., 71b 9 ff. Cf. 72b 5 ff.
