ACCIDENT. This term has a perplexing variety of mean ings, which are, however, not entirely disconnected when con sidered historically. The meaning of the term varies with the antithesis intended. To this, accordingly, attention must be paid in any context in which "accident" occurs. The following account deals with the principal antitheses and attempts to indicate the way in which the term "accident" acquired its various meanings.
(I) Accident and Substance.—Perhaps the oldest use of the term "accident" was by way of contrast with the term "substance" or "thing." "Substance" means the basic reality which has vari ous qualities, stands in various relations, etc. These qualities, relations, etc., on the other hand, need a basis or support to qualify—they are "accidents," accessions to something that is there to bear them (substance). Among the schoolmen, accord ingly, almost any quality was commonly called an accident ; and this usage was fairly common even in the 17th century—"acci dent" and "substance" corresponding roughly to "quality" and "thing" respectively, as these terms are commonly used.
(2) Accident and the Self-existing.—In the strict sense of the term, as distinguished from its more usual meaning even among philosophers, the term "substance" means that which exists in itself and through itself, and when so interpreted its familiar contrast with "accident" naturally prompts the application of the term "accident" to anything that is dependent on some other thing. In this case, even what are commonly called "things" or "substances" will be classed among "accidents." Thus for Spino zism there is only one Substance, namely God, who alone is self existing, while all finite things and even the so-called "infinite modes" (such as motion) are really "accidents," or dependent existents. Cartesianism, too, made this admission, or one very like it to all intents and purposes, but allowed the name "sub stance," in a qualified sense (that is, in the popular sense) to finite bodies and to souls.
(3) Real Accidents.—The antithesis between "accident" and "substance" just explained (2), clearly cuts across the distinction between "quality" and "thing," with which, according to one usage, it coincided more or less Now, some of the schoolmen maintained that there are certain sense-qualities of things which are not dependent on the substances with which they are some times combined, but can exist by themselves, apart from such substances. These alleged independent or self-existing qualities they called "real accidents." (4) Accident and Essence.—The distinctions between "sub stance" and "accident" explained in (I) and (2) naturally led people to regard an "accident" as something less important than substance, as something not essential to substance ; and so the term "accident" was contrasted with whatever is not really essen tial to anything. Thus in logic, for instance, the so-called fallacy of accident is the erroneous assumption that a claim to know any thing or anybody implies a knowledge even of all that is non essential in relation to it or him. Similarly, in the doctrine of the Predicables (q.v.), as commonly expounded in books on logic, the predicable "accident" is contrasted with the other four pred icables in the sense that any predicate asserted of a subject but not essential to it is called an "accident" of it, whereas any pred icate essential to the subject of which it is affirmed belongs to one or other of the remaining predicable's: (5) Accident, Necessity and Design.—The kinship between what is "essential" and what is "necessary" has prompted the common use of "accident" for what is otherwise called a "chance" occurrence. And by a somewhat similar extension of its meaning the term "accident" has come to be applied in law to any occur rence or result that could not have been foreseen by the agent (because not necessarily involved in his action), or to a result not designed (and, therefore, presumably not foreseen), and lastly, to anything unexpected.
(6) "Essential" and "Accidental" Accidents.--One curious con sequence of the multiplicity of meanings of "accident" is that by using the noun in the sense explained in (I) and the adjective in the sense explained in (4) the schoolmen distinguished between "essential" accidents and "accidental" accidents (i.e., qualities).