Commentaria in Primam Partem Summae Theologiae

A clear title. – In the body there are three parts: first, in which intellect falsity is or is not; second, there: Hac tamen differentia, how falsity is found in that intellect in which it is¹; third, there: Quia vero falsitas, how and when falsity is derived from that intellect into the intellect in which it is not².

II. As to the first, this is the conclusion: Falsity is not in the intellect grasping what a thing is, but in composing and dividing. This conclusion is proved by an argument, and it is made manifest both in itself and in its proof by the proportional likeness of intellect and sense. – The argument, then, is this. A natural thing does not fall short of the esse that befits it according to its form, but it can fall short with respect to its accidents or consequents: therefore a cognitive power does not fall short in knowing that thing whose likeness informs it, but with respect to its accidents or consequents: therefore the intellect is not deceived about what a thing is, but in composing or dividing. – The antecedent is proved inductively in man. The consequence, however, is proved as follows: just as a thing is related to its esse through its form, so a cognitive power is related to knowing through the likeness of the thing known: therefore, if the thing cannot fall short, etc. The second consequence, as to its first part, is proved because the intellect is informed by the likeness of the quiddity. As to the second part: because, in composing, something is attributed to the quiddity that either does not follow from it or is opposed to it.

Now the proportional likeness is this: as the sense of sight is related to its proper sensible object, so the intellect is related to what a thing is; and just as the former is informed directly by the likeness of its proper sensible, so the latter by the likeness of the quiddity. And for this reason falsity is in neither, as such. Likewise, just as sight is related to common and incidental sensibles, so the intellect is related to judging of what follows from the quiddity or is accidental to it—which is done by composing or dividing. And for this reason falsity can be in both.

III. Concerning the antecedent, note that it can be interpreted both well and badly. Badly indeed, if it is understood that the esse of a natural thing cannot fail: for this is not true except in incorruptible things. Well, however, if it is understood that the esse of a natural thing cannot fail while that natural thing itself remains intact: and thus the text intends. Hence it does not say that no natural thing can fail; but it says that it cannot fail from the esse that belongs to it according to its form; as if one were to say that no thing having some form, while it has it, can fail from the esse that accords with that form. And this proposition is self-evident: because esse pertains to the ratio of form, as is clear in Book VII of the Metaphysics³.

IV. Concerning the proof of the consequence, namely the proportional one, just as a thing has being through its proper form, so a cognitive power knows through the likeness of the thing known, note that to know is the very esse of the species of the knowable, when it is truly in act in the genus of the knowable⁴; just as we said⁵ that to understand is the very esse of the intelligible species in act in the genus of the intelligible, and not of something existing in an intermediate way. Thus this is common to every cognitive power, whether of the sensitive or of the intellectual order, namely, that to know is the esse of the species by which it knows, taking that species, whatever it may be, in act in the genus of the knowable; whatever may be said of its esse in act in the genus of beings. And this is very much to be noted for the knowledge of the sensitive part and of the intellect.

V. With respect to according to⁶, the conclusion is this: Falsity is in the composing intellect in two ways, namely formally and objectively. – It is proved, and it is made manifest. It is proved indeed: because truth is in the same intellect in the same ways. It is made manifest, however, from the difference with respect to sense, as is evident.

VI. With respect to the third⁷, a single conclusion is put forward, together with its corollary. The conclusion is: Falsity is in the intellect of what a thing is, per accidens. – It is proved and made manifest. It is proved indeed thus. Falsity is per se in the composition of intellects alone; therefore in the intellect of what a thing is it has its place by reason of the composition mixed in with it; therefore it is found in it per accidens. – All the consequences are evident. For the first rests on this, that from one such thing the rest must be said to be such, insofar as they participate in it, as is clear from I Posterior Analytics⁸. The second rests on this, that it is not of the essence of what a thing is to be composite, which is also evident.

The conclusion is made manifest, however, by distinguishing the two ways in which composition is admitted to the intellect concerning what a thing is. The first consists in the joining of the definition to the thing defined; the second in the joining of the parts of the definition, as is clear from the text. And these ways differ in this, that error in the second makes what a thing is false in itself, whereas the first makes it false with respect to this.

The corollary is that in knowing simple quiddities, the intellect cannot be false; it is either true, or there is no act of understanding at all.

VII. Concerning the first mode of falsity, and this corollary, a doubt arises. First, because the joining of a definition to what is defined lies outside the intellect's grasping what a thing is. For the intellect, in grasping what a thing is of a line, does not say, a line is a length whose extremities are two points; it says only, a length whose extremities are two points. For this is the definition, which alone is acknowledged to pertain to the first operation of the intellect; but that whole statement, a line is a length etc., is uttered by the composing intellect, just as it is also said that the line is curved or straight. Why, then, is the falsity of that joining rather than of this one assigned to the first operation? – Second, because this mode of falsity has its place in simple concepts just as in composite ones: for even the most simple concept can be joined to something to which it does not belong quidditatively. And thus even in simple concepts there can be error per accidens: the opposite of which the text of the corollary seems to state.

VIII. For the clarification of these points, know that, just as a thing is related to its being (esse), so is it related to being known: and therefore, to the extent that the conjunction of the definition with the defined differs from its conjunction with other things, so much does it matter that knowledge of that conjunction be required for what a thing is, and not of its conjunction with others. For the conjunction of the definition with the defined gives the definition its character as what a thing is: for no account is a quiddity except insofar as it is the quiddity of some being (ens). And therefore knowing what a thing is does not come about unless the conjunction of the definition with the defined is known. For if the definition were known without knowing whose thing it is, no quiddity would be known, but only what a name signifies: for one who apprehends such a definition would stand in relation to it as we now stand when forming the concept of a golden mountain, or of any other figment composed of non-impossible elements. The conjunction with the passions and other things, however, does not stand in this relation to what a thing is: since the account of quiddity is preserved without them. Therefore, since what a thing is essentially requires in its being (in essendo) that of which it is the quiddity, though not this or that particular one, it must also require it in being known. Hence, that conjunction pertains to the first operation of the intellect, just as does the conjunction of the parts of the definition; though the latter more so.

And since the conjunction of the definition with the thing defined, if judged in itself, arises from the composition of the thing defined (for if it were not composite, the abstraction of a definition from it would have no place in it, insofar as it is of itself; since nothing abstracts of itself from that which is altogether itself); therefore, if any quiddity is found to be so simple—namely, such that it is the quiddity of a simple thing—no error can arise concerning it on its own part, just as there is no composition. – And by this the answer to the objections is clear.

IX. In response to the first, note that quiddity is said to be the proper object of the intellect because the intellect, in general, is related to quiddity as sight is to color; so that it knows per se and in the first instance what a thing is, and by it alone is it perfected and moved per se primo. The reason for this is assigned, first, because the intelligible species is primarily of quiddity, as is said in the body of the article. Second, because in what a thing is is contained the knowledge of every composition, whether of agreement or disagreement: so much so that if anyone were to penetrate perfectly the quiddities of things, he would understand perfectly in them all propositions concerning their accidents, as will be made clear below ⁹ in the treatise on the Angels. Third, because what a thing is is knowable of itself, whereas composition is not knowable except through what a thing is. In sign of this, we know principles insofar as we know terms, as is said in I Poster. ¹⁰; and all doubts we judge by resolving them into what a thing is.