JMC : The Metaphysics of the School / by Thomas Harper, S.J.

Chapter II. Possible Being.


No one will venture to deny, that the idea of possibility is common to all men in every age. There is not another, perhaps, which occurs more frequently in the practical concerns of life. Indeed, mankind in general is so habituated to it, that the term serves for a customary ejaculation of surprise. There will be no difficulty, therefore, in admitting that there must be, and is, a corresponding reality in the order of things, which serves as an objective foundation for such an idea. Every one is conscious to himself that, in gauging the possibility or impossibility, say, of some future event or course of action, he is not dealing with either a phantom of the imagination or a purely logical figment. It is a matter of prudence to determine, before undertaking a work, the possibility of accomplishing it. So again, the credibility of a witness, or even of witnesses, to some unwonted occurrence, is frequently measured by the supposed possibility or impossibility of the story. But it is mere folly to contend that, in these and like cases, possibility and impossibility are simple creations of the mind, and that they are destitute of any real foundation. It must, then, be allowed that the concept of the possible has some sort of an objective basis. The question is, what may that objective basis be?


It will be well to see, whether the derivation of the word can assist towards a clearer and more precise understanding of the nature of possibles. The word, possible, virtually includes the idea of some Power or Faculty (posse, potentia, possibile). Now, Power is either active or passive; and both kinds find their place, only after a different fashion, in the concept of possible Being. For, in the first place, as a merely possible Being does not yet exist, though it might exist, if so be; the possibility of its future existence must depend upon some active efficient Power which is capable of actuating it. This, however, is not enough; since, if the supposed constituents of this possible Being were to exhibit in their combination a manifest contradiction, all the conceived possibility would at once cease, and the general verdict of common sense would pronounce the existence of such an entity an impossibility, quite irrespective of its referribility to an external and efficient cause. Thus, for instance, if one were to suppose a human soul composed partly of granite, partly of certain members of a bird, the mind would at once recognise the intrinsic impossibility of such a Being, and would never think of troubling itself with the further question (which would in the given case be otiose, nay repugnant), as to whether there was a power capable of producing it. 'It is an idle and silly question,' would be the natural reflection; 'seeing that the thing is in itself an impossibility.' In this second way of viewing a thing as possible, the mind conceives in the possible Being a kind of passive or receptive power, by which it admits of concordant elements in its essential constitution. This intrinsic possibility, regarded as inherent in the possible Being itself; is of course logical; yet it must be founded in some reality.


Possibility is, therefore, twofold; internal and external. Internal possibility is that aptitude or capacity of a Being for existence, which is simply due to the concord, or absence of contradiction, in the essential notes by which it would be constituted, if it were to exist. External possibility is the aptitude or capacity of a Being for existence, owing to the presence of a cause which is able to produce it. The distinction will be more clearly understood, perchance, by an example. Let a wall be supposed thirty feet high. A question arises as to the possibility of a man's jumping it. Now there can be no question as to the intrinsic possibility. For a wall five feet high has been jumped; and there is nothing in the addition of feet to make the jump a contradiction in terms. But it is externally impossible; because there are no men now existing who are able to make such a jump. But, if one of the Brobdignagians could be borrowed for the occasion, the possibility of the feat would then admit of no reasonable doubt.


There are two methods by which the idea of possible Being is acquired. The easiest, and first in order of time, is a posteriori; by considering actually existing or once existing entities. Thus: having seen a great number of cats, a man has no difficulty in conceiving the possibility of cats existing in the future. So again, as the Dodo once existed, and there are stuffed specimens to be seen in the Museums of Zoology; though it is now supposed to be extinct, there can be no difficulty in conceiving the possibility of its future reappearance. Again; there have been so many eclipses of the sun in foregone years, that no one could doubt the possibility of an eclipse next year. Hence that proverb, so well known in the Schools, derives its force; 'ab esse ad posse valet illatio,' which may be freely translated, 'If a thing is or ever was, it is fair to infer that it can be.' But the same concept of possible Being may be acquired also a priori. For the human intellect can to a certain extent measure the capacity of finite efficient causes; and knows thus much at least of the first efficient Cause, that Its energy is infinite and can, therefore, produce whatever is producible. So far, then, as external possibility is concerned, there is no difficulty. But how, on a priori grounds, is it possible to determine the internal possibility of a given being, as constituted ideally with such and such essential notes or characteristics? It has been maintained that, if these notes are to human ken concordant and compossible, there is herein sufficient motive for pronouncing the possibility, -- if they are seemingly repugnant, for pronouncing the impossibility, -- of the object. To the first member of this statement there may, perhaps, be no reasonable objection; but the second needs revision or, at least, greater precision. For the natural light of human reason is incompetent to decide on the absolute and objective repugnance of essential attributes or characteristic notes with each other; and that which appears repugnant to us, may prove quite consistent in the order of nature. The word, repugnant, is too vague and general. That Being alone, therefore, can be safely judged impossible, whose constitutives are absolutely contradictory; for then it is not Being at all, and no efficient causality, even Infinite, can terminate in no thing. Thus, God could not create a man to be a lobster. Why? Because it is a contradiction in terms. If the thing is a lobster, it is ipso facto not a man; and the same thing cannot at the same time be and not be. Hence, St. Thomas justly remarks that it is more correct to say, These things cannot be created, than that God cannot create them. The a priori concept, then, of internal impossibility is derived solely from a manifest contradiction in the essential notes of the object; where this contradiction is not apparent, the object may be deemed intrinsically possible.


It is plain that, as all finite Being is contingent and all contingent Being includes in its nature an antecedent possibility of Being or not Being; the mind may make abstraction of the fact of existence in any or every such case, and consider finite Being as possible. There is, accordingly, only one Being Whom possibility can in no way near; and He is the Infinite. But, in the present discussion, it is purely possible Being that is the direct and formal object; and the purely possible directly and explicitly excludes existence. And this is the reason why the purely possible and the actual or existent have been frequently treated as the primordial determinations of Being, while others have claimed that place for the Infinite and Finite. It has been deemed more conducive, however, to clearness and scientific order, as has been already stated, that the former binary should be considered here under the general question of Being: first, because all real Being includes in one way or another the idea of Existence; secondly, because after-investigations will be facilitated by an accurate knowledge of these two Transcendentals; and, thirdly, because confusion is likely to arise from the close juxtaposition of the two Binaries aforenamed, since their respective lines of demarcation intersect. Existence includes Infinite and Finite; while the Finite includes the actual and possible.


External Possibility assumes a twofold phase, according to the nature of the referribility of the possible object to its presumedly efficient cause. For, it is either physically within the reach of that cause, and then it is said to be possible de potentia absoluta; or it is likewise morally within the reach of that cause, and then it is said to be possible de potentia ordinata. In like manner, a thing may not be morally within the reach of a cause, it is then said to be impossible de potentia ordinata; if it is physically out of the reach of the cause, then it is impossible de potentia absoluta. It remains to explain what is meant by the expressions that a thing is morally within, or morally beyond, the reach of a cause. If a free efficient cause can, or cannot, do a thing, having regard to the moral order, the fitness of things, or the principles of right and justice; that thing is said to be morally possible, or impossible, for the given cause. Consequently, a thing may be possible de potentia absoluta, which is impossible de potentia ordinata. Thus, a man can steal physically, but not morally. So again, God de potentia absoluta could make a man with his head where his feet ought to be; but He could not do it de potentia ordinata. So, a king, or his minister, can seize the territory of a less powerful neighbouring state without cause de potentia absoluta; he cannot do it de potentia ordinata. But no cause, Infinite or other, de potentia absoluta can produce an extended spirit.


The doctrine developed in the preceding Prolegomena corresponds in every particular with the teaching of the Angelic Doctor, save in the comparatively unimportant point of terminology. That which here goes by the name of intrinsic Possibility, St. Thomas calls Absolute; while extrinsic Possibility is denominated by him Relative, forasmuch as it includes the idea of relation to an efficient cause. A summary of what he has taught on this subject shall be given by way of confirming and elucidating the preceding pages, following as nearly as possible the order of the Prolegomena. 'The Possible has a twofold signification, as the philosopher teaches (Metaphys. V). One includes relation to some power; as that which is subject to human power, is said to be possible for a man. The other is absolute, having regard to the simple congruity of the terms. . . . A thing is said to be absolutely either possible or impossible on account of the relation of the terms to each other. It is said to be absolutely possible, forasmuch as there is no repugnance between the Predicate and Subject; as, for instance, that Socrates is seated. On the other hand it is said to be absolutely impossible, forasmuch as there is a repugnance between the Predicate and Subject; as for instance, that man is an ass.'{1} St. Thomas understands by repugnance contradiction; as will be seen by the following quotation. 'According to the philosopher (Metaphys. V) there are three meanings of the words Possible and Impossible. One is in relation to some active or passive power; as it is said to be possible for a man by virtue of his locomotive power to walk, but impossible for him to fly. The second has no relation to any power, but is inherent in the thing itself; just as we call a thing possible, whose existence is not impossible, and call a thing impossible, which necessarily cannot exist.' (The third meaning is omitted, as belonging exclusively to Mathematics.) 'Be it known, then, that in the sense in which no relation to any power is connoted but there is exhibited that which is simply inherent in the thing itself', an entity is called impossible, by reason of a certain discoherency of the terms. Now, all discoherence in the 'terms exhibits some sort of opposition. But in all opposition are included affirmation and negation; (as is proved in Metaphys. X). Hence, in every Impossible of such kind, there is implied an affirmation at once and a negation. But nothing of this sort can be attributed to an active power; as is proved. For, every active power or faculty follows the actuality and entity of the being to which it belongs. Now, every agent naturally produces action like itself; hence every action of an active faculty is terminated to Being. . . . But the existence of affirmation and negation has neither the nature of Being nor of no thing; because the Being does away with the not Being, and the not Being does away with the Being. Hence, neither primarily nor consequently, can it become the term of any action whatsoever of any active power.'{2} This is explained more clearly in the following passage. 'Whatever cannot have either the nature of thing or of no thing, cannot be possible; and, therefore, that anything should at the same time be and not be, is in itself impossible; because what is at once thing and no thing, is neither thing nor no thing.'{3} In the words that follow St. Thomas applies the idea of antecedent possibility to the existing universe in accordance with the doctrine contained in the fifth Prolegomenon. 'For it was possible for created Being to have existed before it really did, by the power of that Agent by which it began to be, or by reason of the connection of the terms in which no repugnance is found. In this latter sense, it is not called possible in reference to any power. . . . For the predicate, Exists, is not repugnant to the subject, The World or Man, . . . and so it follows that it is not impossible to be, and, consequently, that it is possible for it to have been before it was, even though there were no power in existence';{4} i.e. its intrinsic possibility would persist. Lastly, St. Thomas thus explains external Possibility de potentia absoluta and de potentia ordinata, though with special reference to God, as the nature of his subject-matter demanded. 'Since, in those who act with liberty of will, the action of the power follows the mandate of the will and order of reason, it behoves us to consider, when anything is ascribed to the Divine power, whether it be attributed to that power considered in Itself?, for then It is said to be capable of that (posse illud) de potentia absoluta; or whether it be attributed to It in relation to His Wisdom and Foreknowledge and Will; for then It is said to be capable of that de potentia ordinata. One must necessarily, then, attribute to the power itself absolutely regarded, (seeing that It is Infinite), the possibility of whatever is in itself something and does not imply a deficiency of power. I say advisedly, What is in itself something, because a union of affirmation and negation is nothing; and (to take an example), to say in one breath that something is at the same time a man and not a man, does not excite any intelligible idea. Wherefore, the power of God does not extend to the point of causing that an affirmation and negation should be verified at the same time. And the same may be said of all those cases which include a contradiction. . . . When, then, to this power absolutely considered is attributed anything which He wills to do and His Wisdom has it in intention to do, then He is said to be capable of that secundum potentiam ordinatam; but when His power extends itself' (i.e. is conceived as extending itself) 'absolutely considered, to that which is attributed to It, although His Wisdom and Will have it not in intention that it should be so done, then It is said to be capable of it de potentia absoluta only.'{5}

Suarez has the same teaching; but he calls external, positive; internal, negative possibility.{6}

Having thus defined the nature and species of possible Being, it is now time to institute a careful examination of the concept, and to determine the ultimate basis on which it rests. This will be done with greater scientific precision, if the progressive analysis of the idea is presented to the reader under the form of a series of Propositions.

{1} XXV, 3, in c.

{2} De Potentia, a. I, a. 3, in C; cf. 1ae, xlvi, I, ad 1m. Sentt. d. xlii, Q. 2, a. 3, in c.

{3} Sentt. d. xlii, Q. 2, a. 2, 3, in C; cf. De Potent. Q. iii, a. 14, in c.

{4} c. Gent. L. II, C. 37, v.f.

{5} Sentt. d. I, Q. 2, a. 3, in C. The whole corpus articuli, as it is called, is worth consulting.

{6} Metphysica, Disp. xxx, § 17, nn. 10-14; Disp. xlii, § 3, n. 9.

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