(a) The attributes which we affirm of substance, other than the notes constitutive of its essence, are divided into proper accidents, or properties in the strict sense (ἴδιον, proprium), and common accidents, or accidents in the more ordinary sense (συμβεβηκός, ac-cidens). A property is an accident which belongs exclusively to a certain class or kind of substance, and is found always in all members of that class, inasmuch as it has an adequate foundation in the nature of that substance and a necessary connexion therewith. Such, for instance, are the faculties of intellect and will in all spiritual beings; the faculties of speaking, laughing, weeping in man; the temporal and spatial mode of being which characterizes all created substances.[254] When regarded from the logical point of view, as attributes predicable of their substances considered as logical subjects, they are distinguished on the one hand from what constitutes the essence of this subject (as genus, differentia, species), but also on the other hand from those attributes which cannot be seen to have any absolutely necessary connexion with this subject. The latter attributes alone are called logical accidents, the test being the absence of a necessary connexion in thought with the logical subject.[255] But the former class, which are distinguished from “logical” accidents and called logical properties (“propria”) are none the less real accidents when considered from the ontological standpoint; for they do not constitute the essence of the substance; they are outside the concept of the latter, and super-added—though necessarily—to it. Whether, however, all or any of these “properties,” which philosophers thus classify as real or ontological accidents, “proper” accidents, of certain substances, are really distinct from the concrete, individual substances to which they belong, or are only aspects of the latter, “substantial modes,” only virtually distinct in each case from the individual substance itself,—is another and more difficult question ([69]). Such a property is certainly not really separable from [pg 238] its substance; we cannot conceive either to exist really without the other; though we can by abstraction think, and reason, and speak, about either apart from the other.[256] Real inseparability is, however, regarded by scholastic philosophers as quite compatible with what they understand by a real distinction ([38]).
A common accident is one which has no such absolutely necessary connexion with its substance as a “property” has; one which, therefore, can be conceived as absent from the substance without thereby entailing the destruction of the latter's essence, or of anything bound up by a necessity of thought with this essence. And such common accidents are of two kinds.
They may be such that in the ordinary course of nature, and so far as its forces and laws are concerned, they are never found to be absent from their connatural substances—inseparable accidents. Thus the colour of the Ethiopian is an inseparable accident of his human nature as an Ethiopian; he is naturally black; but if born of Ethiopian parents he would still be an Ethiopian even if he happened to grow up white instead of black. We could not, however, conceive an Ethiopian, or any other human being, existing without the faculties (not the use) of intellect and will, or the faculty (not the organs, or the actual exercise of the faculty) of human speech.
Or common accidents may be such that they are sometimes present in their substances, and sometimes absent—separable accidents. These are by far the most numerous class of accidents: thinking, willing, talking, and actions generally; health or illness; virtues, vices, acquired habits; rest or motion, temperature, colour, form, location, etc.
(b) The next important division of accidents is that into mere extrinsic denominations and intrinsic accidents; the latter being subdivided into modal and absolute accidents, respectively.
An absolute accident is one which not merely affects its substance intrinsically, giving the latter an actual determination or mode of being, of some sort or other, but which has moreover some entity or reality proper to itself whereby it thus affects the substance, an entity really distinct from the essence of the substance thus determined by it. Such, for instance, are all vital activities of living things;[257] knowledge, and other acquired habits; quantity, the fundamental accident whereby corporeal [pg 239] substances are all capable of existing extended in space; and such sensible qualities and energies of matter as heat, colour, mechanical force, electrical energy, etc. Such, too, according to many, are intellect, will, and sense faculties in man.
There are, however, other intrinsic determinations of substance, other modifications of the latter, which do not seem to involve any new or additional reality in the substance, over and above the modification itself. Such, for instance, are motion, rest, external form or figure, in bodies. These are called modal accidents. They often affect not the substance itself immediately, but some absolute accident of the latter, and are hence called “accidental modes”. Those enumerated are obviously modes of the quantity of bodies. Now the appearance or disappearance of such an accident in a substance undoubtedly involves a real change in the latter, and not merely in our thought; when a body moves, or comes to rest, or alters its form, there is a change in the reality as well as in our thought; and in this sense these accidents are real and intrinsic to their substances. Yet, though we cannot say that motion, rest, shape, etc., are really identical with the body and only mentally distinct aspects of it, at the same time neither can we say that by their appearance or disappearance the body gains or loses any reality other than an accidental determination of itself; whereas it does gain something more than this when it is heated, or electrified, or increased in quantity; just as a man who acquires knowledge, or virtue, is not only really modified, but is modified by real entities which he has acquired, not having actually possessed them before.
Finally, there are accidents which do not affect the substance intrinsically at all, which do not determine any real change in it, but merely give it an extrinsic denomination in relation to something outside it ([60]). Thus, while the quality of heat is an absolute accident in a body, the action whereby the latter heats neighbouring bodies is no new reality in the body itself, and produces no real change in the latter, but only gives it the extrinsic denomination of heating in reference to these other bodies in which the effect really takes place. Similarly the location of any corporeal substance in space or in time relatively to others in the space or time series—its external place (ubi) or time (quando), as they are called—or the relative position of its parts (situs) in the place occupied by it: these do not intrinsically determine it or confer upon it any intrinsic modification of its substance. Not, [pg 240] indeed, that they are mere entia rationis, mere logical fictions of our thought. They are realities, but not realities which affect the substances denominated from them; they are accidental modes of other substances, or of the absolute accidents of other substances. Finally, the accident which we call a “real relation” presupposes in its subject some absolute accident such as quantity or quality, or some real and intrinsic change determining these, or affecting the substance itself; but whether relation is itself a reality over and above such foundation, is a disputed question.
From these classifications of accidents it will be at once apparent that the general notion of accident, as a dependent mode of being, superadded to the essence of a substance and in some way determining the latter, is realized in widely different and merely analogical ways in the different ultimate classes of accidents.
67. Real Existence of Accidents. Nature of the Distinction between Accidents and Substance.—It would be superfluous to prove the general proposition that accidents really exist. In establishing the real existence of substances we have seen that the real existence of some accidents at least has never been seriously denied. These are often called nowadays phenomena; and philosophers who have denied or doubted the real existence of substances have been called “phenomenists” simply because they have admitted the real existence only of these phenomena; though, if they were as logical as Hume they might have seen with him that such denial, so far from abolishing substance, could only lead to the substantializing of accidents ([63]).