A second condition of its being well set out is, that it shall contain neither equivocal term nor equivocal or amphibolical proposition. Thus, if the thesis declares, To perceive is the proprium of an animal, it is equivocal; for it may mean either to have sensible perception, or to exercise sensible perception actually. You may apply the test to such a thesis, by syllogizing from one or both of these equivocal meanings. The respondent will make good his defence, if he shows that there is no such equivocation: as, for example, if the thesis be, It is a proprium of fire to be the body most easily moved into the upper region; where there is no equivocation, either of term or proposition.208 Sometimes the equivocation may be, not in the name of the proprium itself, but in the name of the subject to which it is applied. Where this last is not unum et simplex but equivocal, the thesis must specify which among the several senses is intended; and, if that be neglected, the manner of setting out is incorrect.209

Another form of the like mistake is, where the same term is repeated both in the predicate and in the subject; which is often done, both as to Proprium and as to Definition, though it is a cause of obscurity, as well as a tiresome repetition.210 The repetition may be made in two ways: either directly, by the same term occurring twice; or indirectly, when the second term given is such that it cannot be defined without repeating the first. An example of direct repetition is, Fire is a body the rarest among bodies (for proprium of fire). An example of indirect repetition is, Earth is a substance which tends most of all bodies downwards to the lowest region (as proprium of earth); for, when the respondent is required to define bodies, he must define them — such and such substances.211 An example free from objection on this ground is, Man is an animal capable of receiving cognition (as proprium of man).

Another mode of bad or incorrect setting out is, when the term predicated as proprium belongs not only to the subject, but also to all other subjects. Such a proposition is useless; for it furnishes no means of discriminating the subject from anything; whereas discrimination is one express purpose of the Proprium as well as of the Definition.212 Again, another mode is, when the thesis declares several propria belonging to the same subject, without announcing that they are several. As the definer ought not to introduce into his definition any words beyond what are required for declaring the essence of the subject, so neither should the person who sets out a proprium add any words beyond those requisite for constituting the proprium. Thus, if the thesis enunciates, as proprium of fire, that it is the thinnest and lightest body, here are two propria instead of one. Contrast with this another proprium, free from the objection just pointed out — Moist is that which may assume every variety of figure.213

A farther mistake is, when the predicate declaring the proprium includes either the subject itself or some species comprehended under the subject; for example, when we are told, as a proprium of animal, that animal is a substance of which man is a species. We have already seen that the proprium ought to be better known than its subject; but man is even less known (posterior in respect to cognition) than animal, because it is a species under the genus animal.214

Again, our canon — That the Proprium should be better known than its subject, or should make the subject better known — will be violated in another way, if the proprium enunciated be something opposite to the subject, or in any other way simul natur as compared with the subject; and still more, if it be posterius natur as compared with the subject. Thus, if a man enunciates, as proprium of good, that good is that which is most opposite to evil, his proprium will not be well or correctly set out.215

Perhaps, again, the thesis may enunciate as proprium what is not constantly appurtenant to the subject, but is sometimes absent therefrom; or, intending to enunciate an occasional proprium, it may omit to specify the qualifying epithet occasional. In either case the proprium is not well set out, and a ground is furnished for censure, which ought always to be avoided.216

Moreover, the proprium will not be well set out, if it be such as does not necessarily belong to the subject, but is only shown by the evidence of sense to belong thereunto. In this case, when the subject is out of the reach of sensible perception, no one knows whether the supposed proprium still continues as its attribute. Thus, suppose the thesis to enunciate as a proprium of the sun, that it is the brightest star borne in movement above the earth: the fact that it is so borne in movement above the earth is one that we know by sensible perception only; accordingly, after the sun sets and we cease to see it, we cannot be sure that it continues to be borne in movement. If a proprium knowable as such by sense be chosen, it ought to be one which is also knowable independently, as belonging to the subject by necessity. Thus, if a man enunciates, as proprium of superficies, that superficies is what first becomes coloured or first receives colour, this is a proprium well set out. For we know clearly that it must always belong to a superficies; though we may also obtain the additional evidence of sense, by looking at some perceivable body.217

Perhaps too the thesis may enunciate the Definition as if it were a Proprium; which is another ground for objecting that the proprium is not well set out. Thus, the thesis may enunciate, as proprium of man, that man is a land animal walking on two feet. Here what is given as proprium is the essence of man, which never ought to be affirmed in the proprium. To set out the proprium well, the predicate ought to reciprocate and to be co-extensive with the subject, but it ought not to affirm the essence thereof. A good specimen of proprium well set out is the following, Man is an animal by nature gentle; for here the predicate is co-extensive with the subject, yet does not declare the essence of the subject.218

Lastly, the proprium, to be well set out, though it does not declare the essence of the subject, yet ought to begin by presupposing the generic portion of the essence, and to attach itself thereunto as a constant adjunct or concomitant. Thus, suppose the thesis to enunciate, as proprium, Animal is that which has a soul; this will not be well set out, for the predicate is not superadded or attached to the declared generic essence of animal. But, if the thesis enunciates, as proprium of man, Man is an animal capable of acquiring cognition, — this will be a proprium well set out, so far as the present objection is concerned. For here the predicate declares first the generic essence of the subject, and then superinduces the peculiar adjunct thereupon.219

Thus far Aristotle has pointed out certain conditions to be attended to in determining whether a Proprium is well set out or described, without determining whether it be really a Propium or not. It may perhaps be truly predicated of the subject, and may even admit of a better description which would show it to be a proprium of the subject; but the description actually set out is defective, and the assailant is entitled to impeach it on that ground. He now proceeds to a larger discussion: What are the conditions for determining whether the supposed Proprium be really a Proprium at all, in respect to the subject of which it is predicated? Assuming that the description of it is not open to impeachment on any of the grounds above enumerated, are there not other real grounds of objection, disproving its title to the character of Proprium?220

1. Suppose your respondent to set up A as a proprium of B: you will examine first whether A can be truly predicated of B at all; next, if it can so be, whether it is truly predicable of B qu B, or of every thing that comes under B qu B. Thus, if he contends that not to be deceived by reason is a proprium of scientific men, you will be able to show that this does not hold in geometry, since geometricians are deceived by pseudographemes or scientific paralogisms. Or, should the respondent deny that A is a proprium of B, you will succeed in refuting him, if you can prove that A is truly predicable of every B and qu B. Thus, it is a proprium of man to be an animal capable of acquiring knowledge; because that attribute is truly predicable of every man qu man.221

2. Again, suppose your respondent affirms a given proprium A of B: you will examine whether A can be truly predicated of every thing called B, and whether B can be truly predicated of every thing called A; if not, the alleged proprium will not hold. Thus the affirmation, A god is an animal participant of knowledge, is a true affirmation; but it would not be true to say, A god is a man: wherefore, to be participant of knowledge is not proprium of man; and, if this be the proprium which the respondent undertakes to maintain, you will be able to refute him. On the other hand, if what he undertakes is the negation of a proprium (A is not a proprium of B), you will establish the affirmative against him by showing that of every thing respecting which A can be truly affirmed B can be affirmed also, and vice versÂ. You will thus show that A is a true proprium of B.222

3. Again, the respondent may perhaps affirm the subject itself as a proprium of something inherent in the subject. You may refute this by showing that, if it were so, the same thing would be a proprium of several things differing from each other in species. On the other hand, the respondent may perhaps deny that something inherent in the subject is a proprium: you may then refute him by showing that it is truly predicable of the subject only, and not truly predicable of any thing else.223

4. The respondent may perhaps affirm as a proprium something contained in the essence of the subject: if so, you will refute him by showing this. On the other hand, if he denies something to be a proprium, you will refute him by showing that, though it is not contained in the essence of the subject, it is nevertheless predicable co-extensively therewith.224

5. The respondent may affirm as a proprium that which is not a necessary concomitant of the subject, but may either precede or follow it. Or, on the other hand, he may deny something to be a proprium which you can show to be a constant and necessary concomitant of the subject, without being included either in its definition or differentia. In each case you will have a ground for refuting him.225

6. The respondent may affirm as a proprium of the subject what he has already denied of the same subject under some other name; or he may deny of it what he has already affirmed of it under some other name. You will have grounds for refuting him.226

7. If there be two subjects (e.g., man and horse) the same with each other in species, the respondent may affirm respecting one of them a proprium which is not the same in species with the proprium of the other. Thus, it is not a constant proprium of horse to stand still spontaneously; accordingly neither is it a constant proprium of man to move spontaneously; these two propria being the same in species, and belonging both to man and to horse quatenus animal.227 If, therefore, the respondent affirms the one while he denies the other, you have an argument in refutation. On the other hand, he may propound as thesis the denial of the one proprium, while he affirms or admits the other. Here too you will be able to make good the counter-affirmation against his denial, on the ground of that which he admits. Thus, if it be proprium of man to be a walking-biped, it must also be proprium of bird to be a flying-biped. The two pairs, man and bird, walking and flying, are the same in species with each other, since both pairs are subordinates under the same genus: man and bird are species, flying and walking are differentiÆ, under the same genus animal. This locus, however, is not universally applicable; for perhaps one of the two predicates may not be of exclusive application to the subject, but may belong to other subjects also. Thus walking-biped designates only one variety — man; but walking-quadruped designates several — horse, ass, dog, &c. Walking-quadruped therefore is not a proprium of horse.228

8. There is some difficulty in discussing the proprium, when the respondent is assailed by a sophistical dialectician who avails himself of the equivocal application of Idem and Diversum: contending that Subject with an Accident becomes a different subject — e.g., homo albus, a subject different from homo (so that, when a proprium has been shown to belong to homo, it has not been shown that the same proprium belongs to homo albus); and that the Abstract is a different subject from the Concrete — e.g. cognition, from the cognizing man (so that what has been shown as proprium of cognition has not been shown as proprium of the cognizing man). If the respondent shall himself set up these negatives, leaving to you the task of establishing the proprium against him, you will meet him by saying that homo is not a subject absolutely different and distinct from homo albus, but that there is only a notional distinction, the same subject having here two names each with a distinct connotation: homo has its own connotation; homo albus has also its own connotation, embodying in one total that which each of the terms connotes. And, when the Sophist remarks that what is a proprium of scientia cannot be predicated also as a proprium of homo sciens, you will reply that it may be so predicated, only with a slight change of inflection. For you need not scruple to employ sophistical refutation against those who debate with you in a sophistical way.229

9. The respondent may perhaps intend to affirm as proprium something which by nature belongs to the subject; but he may err in his mode of stating it, and may predicate it as always belonging to the subject. Thus, he may predicate biped as a proprium always belonging to man. Under this mode of expression, you will be able to show that he is wrong; for there are some men who have not two feet. On the other hand, if the respondent denies biped to be a proprium of man, relying upon the statement that it is not actually true of every individual, you will be able to show against him that it is so in the correct phraseology of belonging to man by nature.230

10. That which is affirmed as a proprium may belong to its subject either primarily and immediately, or in a secondary way — relatively to some prior denomination of the same subject. In such cases it is difficult to set out the proprium in terms thoroughly unobjectionable. Thus, the superficies of a body is what is first coloured: when we speak of corpus album, this is by reason of its white superficies. Album is a proprium true both of body and of superficies; but the explanation usually given of Proprium will not hold here — that, wherever the predicate can be affirmed, the subject can be affirmed also. Album is proprium of superficies; and album can be truly affirmed as also proprium of body; but superficies cannot be truly affirmed of body.231

11. The respondent who is affirming a Proprium may sometimes err by not clearly distinguishing in what mode, and in respect to what precise subject, he intends to affirm it. There are ten different modes, in one or other of which he always proposes to affirm it:—232

a. As belonging to the subject by nature. E.g., Biped is by nature a proprium of man.

b. As belonging to the subject simply — in some way or other. E.g., To have four fingers, belongs to Koriskus or some other individual man.

c. As belonging to the species. E.g., It belongs to fire to be the most subtle of all bodies.

d. As belonging absolutely (?p???, ?a??pe? ???? t? ???) — in virtue of the essence of the subject — per se.233

e. As belonging to the subject by reason of some primary intervening aspect or attribute thereof. E.g., Prudence is a proprium of the soul, looked at quatenus reasonable or intellectual.

f. As belonging to that primary attribute or special aspect, logically distinguished and named separately from the subject. E.g., Prudence is a proprium of the logistikon or rationale.

g. As belonging to the subject viewed as possessing or holding in possession. E.g., The scientific man possesses that acquired mental habit which renders him incapable of having his convictions farther altered by discussion.

h. As belonging to some possession held by a possessing person. E.g., Science is unalterable by discussion; where science, a possession of the scientific man, is assigned as subject of the proprium, unalterable by discussion.

i. As belonging to a subject which is partaken or held in participation by another subject lying behind. E.g., Sensible perception is a proprium of the genus animal which genus is partaken or held in participation by this individual man, that individual horse, &c.; whence it may be predicated not only of animal but also of man, as thus participant.

k. As belonging to the ultimate subject partaking. E.g., To live is a proprium of this particular man or horse, participant in the genus animal, in the way just indicated.

Now each of these varieties of the Proprium is liable to its own mode of erroneous setting out or description. Thus the corresponding errors will be:—234

a. Not to add the qualifying words by nature.

b. Not to state the proprium as simply belonging, when it does only belong to the subject now, and may presently cease to belong.

c. Not to state the proprium as belonging to the species. If he omits these words, he may be told that it belongs to one variety alone among the species (e.g., should it be a superlative) and not to others: perhaps it may belong to some conspicuously, and to others faintly. Or perhaps, if he does add the express words — to the species, he may err, inasmuch as there exists no real species properly so called.

e. f. Not to distinguish whether he means to affirm it of B by reason of A, or of A directly: he will lay himself open to the objection that his proprium, and the subject term of which he declares it to be a proprium, are not co-extensive in predication.

g. h. Not to distinguish whether he intends as subject the person possessing, or the possession. If he leaves this undetermined, the objector may attack him on one ground or the other.

i. k. Not to distinguish whether he means as subject the partaker, or the genus which is partaken. Here too the objector will have ground for attack either from one side or from the other.

In case the respondent should enunciate his proprium in any one of the above defective ways, you will thus know where to find objections against him. But, if you undertake yourself to enunciate a proprium, you will avoid laying yourself open to the objections, by discriminating under which of these heads you intend to affirm it.235

12. Again, the respondent may perhaps affirm as proprium a predicate really identical with the subject, though under a different name. Thus, he may declare to t? p??p?? to be a proprium t?? ?a???: you may then refute him by showing that p??p?? is identical with ?a???. If he is on the negative side, denying A to be a proprium of B on the ground that A is identical with B, you will make out the affirmative against him by showing that A is not identical with B, but only co-extensive and reciprocating therewith. Thus, you may show that animated substance is not identical with animal, but a proprium of animal.236

13. Where the subject is homoeomeric, the respondent may declare as proprium of the whole what cannot be truly affirmed as proprium of a part separately; or he may declare as proprium of a part separately what cannot be truly declared as proprium of the whole. In either case, you have a plausible argument for refuting him; but your refutation will not be always conclusive, because there are various cases in which what is true of each homoeomeric part is not true of the whole; and vice versÂ. If your position in the debate is affirmative, you will select as illustration some case in which what is by nature true of the whole is also true of each separate part: e.g., The earth as a whole, and each of its parts, tend by nature downwards. This is a proprium of the earth.237

14. Respecting Opposita, there are different loci for different varieties.

a. Contraria. — Suppose the respondent to affirm A as proprium of B: you will examine whether the contrary of A is proprium of the contrary of B. If it be not, then neither is A proprium of B. Thus, if best is not a proprium of justice, neither can worst be a proprium of injustice. If the respondent is on the negative side, you may prove the affirmative against him by showing that the contrary of the alleged proprium is a proprium of the contrary of the alleged subject.238

b. Relata. — Suppose the respondent to affirm a relatum A as proprium of a relatum B, you may refute him by showing that the correlate of A is not proprium of the correlate of B. Suppose him to deny the same, you will refute him by proving the affirmative between correlate and correlate.239

c. Habitus et Privatio. — Suppose the respondent to affirm an attribute of the habitus B, as proprium thereof: you may refute him by showing that the corresponding attribute of the privatio correlating with habitus B, is not proprium of that privatio. Suppose him to take the negative side, you will refute him by proving the affirmative of this latter proposition.240

15. Respecting Contradictory Propositions (affirmation and negation of the same), more than one mode of dealing may be stated. Wherever the affirmation is a proprium of the subject, the negation cannot also be a proprium thereof; and vice versÂ. If the affirmative predicate be not a proprium of the affirmative subject, neither can the negative predicate be proprium of the negative subject; and vice versÂ. If the affirmative predicate be proprium of the affirmative subject, the negative predicate will also be proprium of the negative subject. The same predicate cannot be proprium both of the affirmative subject and of the negative subject.241

241 Ibid. p. 136, a. 5-b. 2. This locus is declared by Aristotle to furnish arguments for refutation only, and not for proof.