Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

Around prior knowledge, the Philosopher lays down four points. First, as the foundation and root of the others, that every intellectual learning proceeds from prior cognition. It is called intellectual to distinguish it from sensory cognition; not every sensory cognition proceeds from prior cognition, for then the process would continue to infinity. Rather, it stops at the cognition of the external senses, which does not arise from some prior cognition.

Second, the things that must be presupposed before every learning and teaching are three: the subject, the attribute, and the premises or principles. For demonstration is constructed from these: we demonstrate an attribute of a subject through certain principles that are better known. Prior knowledge—that is, what must be known beforehand about such preknown things—is twofold: whether something exists and what it is. But because principles are complex and not simple, one does not know beforehand of them whether they exist or what they are, but that they are true. For the principles of demonstration must be true, since they not only infer but also establish the truth of its conclusion.

Third, there is an order among prior cognitions—not on the side of the subject and attribute, but on the side of the principles or premises, because the major premise can be known earlier in time than the conclusion, while the minor is known at the same time as it.

Fourth, a conclusion cannot be known beforehand formally, since it is demonstrated; it can be known only virtually, because the premises are known beforehand, and the conclusion is contained in them virtually.

We need not dispute here the last two points. The fourth presents no difficulty, and we shall discuss the third in article 3. Therefore, only the first two points remain to be explained.

Concerning the first, two things should be observed. FIRST: Authors disagree about what is meant by “intellectual teaching and learning”—whether it refers to every kind of cognition without qualification, or only to discursive or scientific cognition. One might understand that every intellectual cognition arises from another, insofar as the second operation arises from the first and the first apprehension from sensory cognition. Yet that does not serve the Philosopher’s purpose. He speaks only of cognition that proves by rational and discursive means, whether scientifically or probabilistically, as the passage is understood by St. Thomas, 1. Poster., lect. 1.¹ “Teaching” is cognition itself insofar as it teaches and makes us know; “learning” is the reception of cognition from another.

The reason is that Aristotle’s sole purpose is to show how something can be newly known, or cognition acquired, without either an infinite regress in proofs or a circle in which one thing is proved through another and conversely. For this purpose it was relevant to speak only of cognition acquired through proof and inference: cognition that is proved and proving, inferred and inferring. A proving cognition need not itself arise from some earlier proving cognition, because a cognition can be self-evident and not derived from another proof. Every cognition that is proved or demonstrated, however, presupposes another prior cognition from which it is proved or demonstrated. Whether cognition in us must arise from another cognition—namely, sensory cognition—not because it proves or is proved but simply because it is intellectual, is not relevant here. This discussion is not about whether the intellect depends on sense, but whether learning and teaching depend on some prior cognition.

SECOND, observe that Aristotle proceeds in explaining the generation and acquisition of our knowledge in the same way as he does in the Physics concerning the generation of natural things. Just as he proves there, against certain philosophers, that forms do not preexist actually, hidden within matter, but are drawn out from matter’s potency and thus acquired anew, so knowledge is acquired in us concerning conclusions—not because the conclusions are presupposed as already known in act and are said to become newly known only by recollection, as Plato held, but because they are known virtually and potentially in the principles, while the conclusions are made actually known and proved from those very principles.

From this the basis of Aristotle’s proposition is clear: every teaching and learning proceeds from prior cognition. That is, every unknown conclusion is deduced from some better-known principle, in which that conclusion is unknown in act but known virtually and potentially—just as things are generated in act not from nothing but from something in which they are contained potentially, namely matter. The Philosopher, then, speaks of knowledge acquired in the human way through principles and inference, which pertains to discourse.

Concerning the second point, carefully distinguish the grounds from which it follows both that something must be known beforehand for us to acquire knowledge and that there should be only three preknown things and two kinds of prior knowledge. The necessity of knowing or presupposing something beforehand arises from the principle that there can be neither an infinite regress nor a circle in demonstrations. It necessarily follows that we must stop at some cognition that is not proved through another; and, consequently, that cognition is presupposed or known beforehand in order to prove or demonstrate other things, but is not itself proved or known through another.

That the preknown things are three follows from the very object that can be demonstrated: a conclusion in which a proper attribute is predicated of a subject and demonstrated to belong to it. Aristotle therefore assigns preknown things only for demonstration, although they can readily be adapted proportionally to nondemonstrative syllogisms. Thus St. Thomas gathers these preknown things in 1. Poster., lect. 2.²: “We must know,” he says, “that what is sought to be known through demonstration is some conclusion in which a proper attribute is predicated of a subject, and this conclusion is inferred from certain principles. Since cognition of simples precedes cognition of composites, before one has cognition of a conclusion one must know in some way both the subject and the attribute. Likewise, one must know the principle from which the conclusion is inferred, since the conclusion becomes known through cognition of the principle. There are two modes of prior knowledge for these three things—the attribute, the subject, and the principle—namely, whether they exist and what they are. But it was shown in 7. Metaph.³ that complexes are not defined: there is no definition of a white man, and much less of any proposition. Since a principle is a proposition, then, one cannot know beforehand of it whether it exists, but only whether it is true. One can know what an attribute is, but since its quiddity depends on the subject in which it exists, one knows the attribute through demonstration as an inferred conclusion, while one knows beforehand what it is only as to the signification of its name; for one cannot know whether something exists unless one knows what its name signifies. A conclusion does not show what its subject is, much less whether it exists. One must therefore know beforehand of the subject what it is and whether it exists, since its definition supplies the principle for demonstrating that the attribute belongs to it.” Thus far St. Thomas.

From this teaching one can clearly infer the number of preknown things and what must be known beforehand about each. This is derived from a single principle: to infer a conclusion from principles, those principles must be presupposed before the demonstration—that is, known beforehand. Principles are propositions composed of terms; therefore, the terms themselves must all the more be known beforehand. There are three terms that concur in a demonstration: the subject and attribute in the conclusion, where they are joined to one another; and the subject and attribute in the premises, where they are joined in the middle term. By the force of that middle term, they are inferred as connected to one another. The middle term is the very quiddity of the subject, because every necessary connection among attributes arises from the necessary connection of quiddative predicates.

Therefore, only the subject and attribute need to be known beforehand insofar as they are presupposed in the premises and later joined in the conclusion. The same applies to the principles themselves, which contain the quiddity or definition of something; consequently, what is known beforehand in them is the middle term, namely the essential predicate in the definition, by reason of which the proper attribute belongs to the subject. It follows that what is known beforehand about the principles themselves is that they are true, since they are propositions.

What must be known beforehand about the subject itself is what it is, because the subject’s quiddity is not demonstrated but is the basis from which demonstration proceeds, and so is presupposed. A fortiori, one knows beforehand of the subject whether it exists, since the question whether it exists is presupposed to the question what it is. One cannot know what something is unless one presupposes that it exists. By “whether it exists,” we mean not merely its actual existence, which accrues contingently to its quiddity, but also its possibility—that is, whether something can be given in its genus, either in reality or in reason. In a word, the question whether it exists asks about the thing, not its cause: whether the thing exists or is given, but not why it is given. It asks whether the thing exists not according to contingent and accidental existence—which does not block the way to knowing what it is—but according to its proper concept, as Cajetan rightly notes in 2. Poster., cap. 7: whether it can be given.

Finally, we cannot know beforehand of an attribute what it is or whether it is such an attribute, because both are concluded through demonstration, which shows that the attribute belongs to the subject and, consequently, is found in and possessed by it—its existence—and depends on the subject in its intrinsic account—its quiddity. It remains, then, that we know beforehand only what the name signifies, because this cannot be demonstrated.

ARGUMENTS ARE SOLVED.

Against the first point, one may argue that Aristotle’s proposition, “Every teaching and learning, etc.,” either applies universally to every cognition or only to discursive and probative cognition. If the first, consider the cognition of angels, whose most perfect knowledge does not arise from prior cognition but apprehends principles and conclusions in a single intuition. Consider also our own case: since there can be no infinite regress, we must arrive at some cognition that does not arise from another prior cognition. If the second, the Philosopher’s proposition is not true, because discourse includes not only the conclusion but also the premises; therefore such discursive cognition does not arise from prior cognition but from itself, insofar as the conclusion is deduced from the premises it includes.

This is confirmed because the proposition does not answer Plato’s argument that we learn nothing new. Either we know what we seek, Plato argued, or we are ignorant of it. If we know it, then we already know it; if we are ignorant of it, even if it comes before us, we will not find it—just as someone will not find a person unknown to him. The same argument holds if every teaching proceeds from prior cognition: no matter how much prior cognition I have, if it does not show me what I seek, I will never find it; if it does show me, there is no further need to seek.

I ANSWER from what has been said: the Philosopher’s proposition is understood of cognition obtained through some proof, since this is properly teaching and learning: what we intend to learn is what we acquire through proof. What is not proved through another but apprehended immediately in itself is not learned and is not an object of learning. Thus there is no objection from the angel, who sees without proof the thing proved and without inference or discourse the thing inferred. Nor is there an infinite regress: we stop at a proving cognition that is not proved from another prior cognition, as with first principles, although ultimately this is resolved into cognition of the senses.

As for the claim about discourse, the answer is that if “discourse” is taken adequately to include both premises and conclusion, then it is true that discourse proceeds from prior cognition: from cognition of the principles in themselves, as grasped precisely through the habit of principles, we proceed to cognition of them as inferring, and consequently to the conclusion. If, however, discourse is not taken so adequately but as the cognition proved through discourse—which is the conclusion, and the only thing to which teaching and learning properly belong—then that cognition proceeds from prior cognition, namely, from the cognition of the premises that proves it. We might say, then, that every teaching—that is, every cognition proved through discourse, or discursive insofar as it is proved—proceeds from prior proving cognition.

The reply to the confirmation is that the Philosopher’s proposition answers Plato’s argument. If every learning proceeds from prior cognition, the conclusion is known virtually and generally in that prior cognition, insofar as it is contained in the premises, but is unknown formally and particularly. Thus cognition of it in potency gives rise to cognition of it in act; actual knowledge of it is not presupposed, as Plato held.

Second, one may argue against the second point, both against the number of preknown things and against the distribution of kinds of prior knowledge.

Against their number: the goodness of the inference to the conclusion must also be known beforehand, but the Philosopher does not list it here. Further, the middle term is known before the conclusion, since the conclusion is inferred by its force; therefore not only the subject and attribute should be known beforehand.

Against the distribution of prior knowledge: sometimes we inquire about the subject itself, whether it exists and what it is, in a given science—as when we inquire in theology whether God exists, and in physics whether motion or generation exists, and so on. And when something is defined, there is often controversy over whether it is defined well or badly, all of which is settled through science and discourse. Therefore we do not know the subject beforehand in the way Aristotle asserts.

Moreover, that “whether it exists” which is presupposed concerning the subject and attribute must refer either to existence or to truth. It cannot refer to truth, because then one would know beforehand of the subject the same thing as of principles: that it is true. But it cannot refer to existence either, because existence is not required for the subject to be knowable, since the object of science abstracts from existence. If one says that the existence presupposed is possible existence, there are two objections: first, science is given even of a being of reason—namely, Logic—and yet its possibility is not presupposed, since it is not a possible being; second, possible being is the same as not being fictitious, but true; thus what is presupposed would be whether it is true, not whether it exists.

Finally, it is wrong to say that only the name of an attribute is presupposed, for one also presupposes whether the attribute exists. Further, one cannot presuppose what a name signifies unless one presupposes whether the attribute signified by the name exists. Further, from the fact that an attribute belongs to some account, one infers that it belongs to the subject, as when we say: “Everything rational is capable of laughter; every human being is rational; therefore every human being is capable of laughter.” Here “capable of laughter” is posited in the premises as belonging to the rational, and from that one infers that it belongs to the human being. Therefore, one presupposes in the premises whether the attribute exists—and indeed also what it is, namely, that it belongs to what it flows from and to which it belongs per se. So of the attribute one does not presuppose only what its name signifies. Nor do we prove an attribute through the signification of its name, but through its fittingness to the subject; what is presupposed about the attribute is that through which it is proved.

I ANSWER the first part of the argument: Aristotle does not count the goodness of the inference among the preknown things because it is not a posterioristic preknown thing but a prioristic one, which he had treated in the books of Prior Analytics. As for the middle term, it is indeed known beforehand, but not separately from the principles, because the principles must be formed from the middle term so as to infer the conclusion. The subject and attribute, however, are known beforehand separately from the principles, because they belong to the conclusion as its matter, of which the conclusion is composed; they are not found precisely in the principles as the middle term is.

To the second part of the argument, the answer is that one always presupposes whether the subject exists in the science that treats it as its proper and adequate subject, in such a way that this is not proved through an intrinsic middle term. Yet one can sometimes prove in a science whether some subject exists and what it is, not through an intrinsic and a priori middle term, but either a posteriori or from principles borrowed from another science rather than from its own, or because that science is subalternated to another and proves its principles through it. Thus theology proves that God exists by borrowing arguments from Metaphysics; and Logic likewise proves from Metaphysics that a being of reason is given. The physicist, however, does not prove that motion in general, or mobile being, is given, since that is the adequate subject; he can prove that generation is given, which is an inadequate and partial subject.

To the third part of the argument, the answer is that the question whether something exists does not refer to existence but to possibility. A being of reason, too, has its possibility—not in order to exist, but to be cognized. The possibility of a thing is not presupposed as a formal and complex truth in the manner of an assertoric statement, as is presupposed of principles; rather, it pertains to transcendental and subjective truth. Possibility is said to pertain to the question whether something exists when it is considered not in signate act, as a quiddative predicate of essence distinguishing it from an impossible or fictitious being and expressing the causes of such possibility, but insofar as it simply exercises an order toward existence, which is extrinsic to quiddity, without considering the causes of such possibility.

Finally, to the last argument, the answer is that some hold that one knows beforehand whether an attribute exists because the attribute’s being follows on the being of the subject. But since that being follows through some middle term, by reason of which the attribute belongs to the subject and is proved of it, it is not presupposed but demonstrated. Therefore, when one knows what the name signifies, one does not know whether the thing signified exists, but only whether it exists in signification—or, rather, in the being of what is signified. Likewise, since an attribute is an accident whose being is understood through its order to a subject, even if in the premises it is understood to belong to some middle term, by reason of which it belongs to and is convertible with the subject, it is not yet understood formally and explicitly in relation to the subject, but only virtually, insofar as it is contained in that middle term. Therefore it is not presupposed as to whether it exists, but is proved, since the attribute’s being is understood through its order to the subject and its fittingness to it, even if it belongs to the subject through some middle term. If whether it exists is not presupposed, much less is what it is. The attribute is not inferred to belong to the subject from the signification of its name alone, though that signification is known beforehand, but from its connection with the middle term, which is also known beforehand in the principles.