Disputationes metaphysicae

1. The reason for doubt on each side.—This question is proposed chiefly on account of Aristotle, who, Metaphysics IV, c. 3, text 8, taught that that principle, it is impossible for the same thing at the same time to be and not to be, is the first and almost the only one, to which all the demonstrations of this science, indeed also of the other sciences, must be resolved, at least virtually. But on the contrary there seems to be, first, that the proper and intrinsic principles of a science must be taken from the cause or reason on account of which the predicate belongs to the subject; whence the same Aristotle, Posterior Analytics I, teaches that the posterior attribute is demonstrated through the prior, but the first of all either is not demonstrated, but belongs immediately to the subject, or is demonstrated as regards us only through the definition of the subject; but the definition itself is in no way demonstrated, but is known immediately of the subject. So, then, in every science the first principle will be that in which either the first attribute is predicated of the subject or the definition of the thing defined; therefore in the present science too the proper and intrinsic principles will have to be taken from the connection of the first attribute with the notion of being, or of the notion of being with being itself; this, therefore, will be the first principle, everything which is, is one, because one is the first attribute of being, as we have said; or certainly this: every being is that which has an essence. It is not, therefore, that one: it is impossible for the same thing at the same time to be and not to be, because that is very extrinsic, and cannot serve for proper a priori demonstrations, but at most for reduction to the impossible. Add that that principle is reduced a priori to this one: every being is one; for a thing cannot at the same time be and not be for this reason, that it can only be determinately one. In which way many say that it belongs first to being, in so far as it is being, to be divided from non-being, which property they think is included in unity, of which we shall see afterwards. Finally the difficulty is increased, because even among the principles in some way intrinsic and most universal that one does not seem to be the first, because it is negative; but every negation is founded on some prior affirmation; therefore there is another principle prior to it, in which it is founded, such as will be either this one, it is necessary that the same thing be or not be, or this one, one contradictory necessarily destroys the other.

Some more certain pronouncements for declaring the sense of the question

2. Metaphysics needs principles into which it ultimately resolves its conclusions.—In this matter all agree that in metaphysics (as in the other sciences) some first self-evident principles are necessary, by which attributes are demonstrated, whether the discussion is of the transcendental attributes of being as being, or of the more special properties of certain beings as they are within the breadth of the formal object of metaphysics, according to what was said in the prooemial disputation; although, because being as being, in order to this science, is prior to the rest, the attributes adequate to it are also prior, and consequently also the most universal principles, which in some way consist of the transcendentals themselves, are prior to the rest; and therefore we are now dealing especially with them. That such principles are necessary, then, the reason is the same in this science as in the others, because it too proceeds through demonstration, resolving conclusions into principles; in which resolution it cannot proceed to infinity, as is evident from the general doctrine about causes; for in no genus of causes can one proceed to infinity; therefore it is necessary that it stop at principles or self-evident propositions.

3. A single principle does not suffice for this function.—Secondly, from this reason it seems to be concluded that these principles must be not only one, but several, and at least two, at least in so far as they are immediate propositions and indemonstrable a priori. The reason is that nothing can be concluded from one principle alone, as is evident from dialectic; because formal inference requires three terms, which cannot be in one principle; therefore the ultimate resolution is necessarily made to two immediate principles. Because, if one is immediate and the other demonstrable, that which is demonstrable will have to be further resolved and demonstrated; but it cannot be demonstrated through the other immediate principle alone; therefore another must be adjoined; and if that too is demonstrable, another will have to be sought through which it may be demonstrated; lest, then, one proceed to infinity, one must stop at something also indemonstrable; several first principles, therefore, are necessary in this science too. And hence it follows that, if we speak of the first principle in this sense, namely as it expresses only an immediate or self-evident proposition, in this sense a single first principle is not to be sought in this science; nor could Aristotle have spoken in this sense in the place cited, because in truth there is none which is in this way single and only first. In another sense, then, a principle prior to the rest can be inquired into, namely either because it is better known to us, or because in use or causality it is prior and more universal, or because it is in every way more indemonstrable; and in this sense there is a controversy among authors which is the first metaphysical principle.

Various views

4. The first opinion is that that which we reported from Aristotle is not the first, but this one, every being is being. So Antonius Andreae holds, Metaphysics IV, q. 5. And to Aristotle he answers that he called that other one the first principle among those which are circulated as general, such as every whole is greater than its part, etc. But this author does not speak rightly even in his own principles, because that proposition is identical and nugatory; and therefore in no science is it taken as a principle of demonstration, but is outside every art. Otherwise in every science the first principle would be that in which the subject of the science was predicated of itself. And the first principle of one science would be as self-evident as that of another; for every identical proposition is equally known, as mobile being is mobile being, just as being is being. And in this science there would be several principles equally known, although not equally universal, as Substance is substance, Accident is accident. He would therefore speak more plausibly if in place of being he took some definition or description explaining the notion of being, and predicated it of being; for although the definition and the thing defined are the same in the thing, the proposition in which the definition is predicated of the thing defined is nevertheless not identical, but doctrinal, because in it a distinct concept is predicated of a confused one. And in this way the reason for doubting posited at the beginning favours this opinion. It seems, however, to be repugnant to Aristotle, in the said c. 3 of Metaphysics IV, when he absolutely concludes that that principle, it is impossible, etc., is simply the first of all, and that all demonstrations are resolved into it.

5. Others say that not that one posited by Aristotle, but this one, it is necessary that anything whatever either be or not be, is the first principle of all, on account of the reason touched upon above, because this is affirmative, while that other is negative. For it is not true, as Javellus, Metaphysics IV, q. 6, thought, that those two principles signify the same thing in diverse words, and so are not to be reckoned two, but one; for, if the matter is considered more attentively, the things which are signified by those principles are diverse. For just as in contraries, or privative opposites, it is one thing that they cannot belong at the same time to the same thing, another that one of them must necessarily belong, as is self-evident, so also in contradictory opposites these two are formally and rigorously diverse. But these are signified by those two principles; for by that one, it is impossible for the same thing at the same time to be and not to be, the repugnance of contradictory opposites is signified; but by that one, anything whatever either is or is not, their immediacy is signified, namely that no medium can fall between them. And so they are posited as distinct by Aristotle, Metaphysics IV, c. 7, texts 27 and 28, and Book III, c. 2, and Posterior Analytics I, c. 8, texts 26 and 27, where he posits the same principles in dialectical terms: It is impossible for the same thing at the same time to be affirmed and denied of the same thing; It is necessary that the same thing be affirmed or denied of the same thing; which in other words are wont to be said by the dialecticians: It is impossible that two contradictories be at the same time true, and, it is impossible that they be at the same time false; which two it is evident are very diverse, and that the first is founded on that principle, it is impossible for the same thing at the same time to be and not to be; but the second on the other, it is necessary to be or not to be. From these reasons, however, it is at the same time evident, comparing these principles among themselves, that that one about the impossible posited by Aristotle is prior to the other about the necessary. First indeed, because it is more self-evident that contradictories have repugnance among themselves than that they have immediacy. For the former at once shines forth in the terms themselves, but the latter needs some discourse and declaration. Whence the former is common to all opposites, for in so far as they are opposites they fight among themselves; but the latter does not belong to all, as is evident from the chapter on Opposites. Secondly, because it is prior according to reason that two contradictories cannot be at the same time true than that they cannot be at the same time false, just as truth is of itself prior to falsity.

Resolution of the question

6. Two kinds of demonstration and their properties.—In order, then, to answer the question, it is necessary to distinguish a twofold kind of demonstration: one is called ostensive, the other reducing to the impossible. The first is per se and directly required for science; and in it one proceeds from causes to effects and from the essence of the thing to demonstrating attributes; for we are speaking of a priori science and of the reasoned fact; for that which is a posteriori is not resolved into the principles of which we are now dealing, but rather into experience. The second kind of demonstrating is not per se necessary, but is sometimes adjoined on account of the defect, ignorance or obstinacy of man; and it is useful not only for persuading and proving conclusions, but also first principles; which cannot be done in the former mode, because, since they are immediate, they do not have an a priori middle term through which they may be proved; yet by reducing to the impossible their truth can be shown, and the intellect convinced to assent to them. Indeed in every kind of demonstration, although the principles demonstrate the conclusion a priori and are self-evident, the force of the inference is virtually founded on reduction to the impossible, namely because it cannot happen that the same thing at the same time is and is not, or that two contradictories are at the same time true. On account of which Averroes said, Metaphysics II, c. 1, that without that principle posited by Aristotle no one can philosophize, dispute or reason.

7. What the mode of demonstrating a priori in this science is.—It must be said, then, first of all, that for demonstrating a priori the attributes of being of being, the first principles must be taken either from the notion of being itself, or from its first attribute for demonstrating the posterior ones; and the discourse made at the beginning convinces of this. And it is confirmed, for as regards this the reason is the same concerning this science as concerning the others; for since the properties of being are in their own way its attributes, it is necessary that they arise from its intrinsic notion and essence, because this is of the intrinsic notion of a proper attribute; they will therefore be able to be demonstrated through the very essential notion of being, whether this be through the distinction of the things themselves among themselves or in order to our concepts and discourses, so that one is truly the reason of another, which suffices for human science and demonstration. Whence, if the attributes of being are so connected among themselves that one arises from another, that which is first will constitute one principle for demonstrating the others; but if (as can sometimes happen) several attributes are immediately connected with the notion of being, they can be demonstrated of being only through the notion of being itself; but how this is done will be evident afterwards in the course of the science. In this order, then, the first principle will be that in which the notion or essence of being distinctly conceived is predicated of being itself.

8. What the first principle of reduction to the impossible is.—Secondly it must be said that in the other kind or mode of demonstrating through reduction to the impossible, the first principle on which that whole mode of demonstrating rests is: It is impossible for the same thing to be and not to be. This is self-evident, because every reduction to the impossible finally stops at this, that it follows that the same thing at the same time is and is not; and as long as it is not reduced to this, the impossibility has not been sufficiently demonstrated; but after it has been reduced to this, one stops there, as at the last term of resolution and the best-known principle. And although sometimes the impossible can be reduced to another inconvenience, that two contradictories are at the same time false, or that the same thing neither is nor is not, nevertheless this very thing is impossible in so far as it virtually includes the other, namely that at the same time something is denied and not denied of something, which is to affirm and deny the same thing of the same thing.

9. What the absolutely first principle of human science is.—Thirdly it must be said that hence it comes about that that principle, it is impossible for the same thing at the same time to be and not to be, is simply the first in human science, and especially in metaphysics. The reason is that that principle is rightly called first from which the whole of human science takes its firmness; but such is the aforesaid principle, because from it not only conclusions but also first principles are demonstrated. Indeed Fonseca adds, Metaphysics IV, c. 3, q. 1, sect. 3, that through that principle first principles are confirmed a priori. But I do not see why he calls reduction to the impossible a priori, since it is not from a cause, but through an extrinsic middle term. Unless perhaps he understands that through a principle of this kind there is demonstrated a priori not indeed the truth of the other principles, which cannot be done, but the impossibility and repugnance which follows from the opposite; for the ultimate resolution of every repugnance is made to contradiction, to which reduction is made through that principle. This, however, is enough for that principle to be called simply first; for, since human talent does not at once comprehend the other first principles as they are in themselves, it is much helped and confirmed in its assent to them by reducing to the impossible, which in the others can be done through that first one; but that one itself can in no way be shown, even by reduction to the impossible, because nothing more impossible can be inferred than that which is pronounced in it, which is a sign that it is most known and first. I said, however, that the use of this principle is most necessary in this science, because, since being is most simple, it can scarcely be defined, and its notion more distinctly explained and applied to making true demonstrations, so that the propositions assumed are not judged identical.

The opposing reasons are solved

10. To the reason for doubting posited at the beginning, then, as regards the former part, it has already been explained that Aristotle does not call that principle first because metaphysics uses it for its proper and direct demonstrations; for rather the same Aristotle, Posterior Analytics I, c. 8, text 26, says that that principle is not wont to enter formally into demonstration. It is called the first principle, then, for the other reasons already explained; for it is as it were the universal foundation by virtue of which all demonstrations rest, and the other principles can, at least as regards us, be declared and confirmed, although this is always done with some other principle adjoined, either conceded or self-evident. To the first confirmation the answer is that the truth of that principle is not properly founded on unity, but on the opposition and repugnance of contradictories; whence it will not rightly be proved that what is cannot at the same time not be because what is one is only one; both because, as I shall say below, being in so far as it is one is not properly divided from non-being, but from another being, because it is rather divided from non-being in so far as it is being; and also because this very division of being from non-being is founded on this, that the same thing cannot at the same time be and not be, on account of the formal repugnance of these terms. To the last confirmation it is said, first, that it can indeed happen that some affirmative proposition, in so far as it is simpler than a negative, is prior to it in the order of generation or composition, and yet that in the notion of self-evident truth it is not so manifest, nor equally first; and so it can be said of that principle; for although its whole truth is founded on the nature of being itself, which of itself excludes not-being, nevertheless this very thing is explained through that principle, although negative, most evidently and most aptly for founding demonstrations reducing to the impossible.

11. What the first principle is in the genus of morals, and a comparison with the first in the genus of nature.—And hence many arguments are easily solved which are wont to be made against the opinion of Aristotle about this first principle, such as that it consists of many words, neither most universal nor very known, such as simul, idem, which signify relations, which are posterior to absolute things. Likewise, that it is a modal proposition, which supposes a prior one de inesse. For to these and similar arguments it is said that at most they prove that this is not the first proposition or combination which the intellect forms, but not that it is not the first principle, because for this it is not necessary that it be the first proposition, but only that the science of all other truths depend in a certain way on it, while it itself is so true, known and indemonstrable that it does not depend on another; but these belong to that principle, as has been shown. That principle, however, could be reduced to simpler terms by saying: No being is and is not; for so it is made up of simple terms, and of the most universal and first ones, which is necessary in the first principle, so that it can be common to all sciences, as St. Thomas noted, I-II, q. 94, a. 2. Where he notices that this principle is first in speculative matters; for in practical or moral matters there is another first, namely, every good is to be done and evil avoided; for, because all moral actions are concerned with good and evil, therefore the first moral principle had to consist of those terms; yet, because practical things are founded on speculative, therefore what is the first principle in speculative matters is simply and absolutely first. But whether this principle is so known that it can be denied in the mind by no one, although he seem to contend with the voice; likewise by what modes it is to be persuaded against one who obstinately denies it, either by refuting him from what he has conceded, or by reducing him to inconveniences repugnant to the senses, Aristotle treats at length, Metaphysics IV, cc. 3, 4 and 5, in which places the expositors can be seen, because there is no reason why we should linger further on this matter.