Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

There is no need to linger over explaining what is understood by the name “science”; it is clear that it means a habit acquired through demonstration and inclining one toward demonstration. Demonstration signifies a certain and evident proof of some truth. Although this certainty and evidence require resolution as far as first principles, which are perhaps found in very few cases and concerning few subjects, this is not due to a defect in science but to a defect in those who know. For most know only with imperfect, almost subalternated science, because they believe principles handed down by another science rather than resolving them within it.

LET THIS, THEN, BE THE CONCLUSION: Logic is truly and properly a science, and at the same time an art, though a liberal one.

Hardly anyone doubts this conclusion, although some have wished to say that Logic is not a science but a mode of science. St Thomas plainly calls it a science in Metaphysics IV, lect. 4¹, and Summa theologiae I–II, q. 57, a. 3, ad 3 and a. 6, ad 3. Likewise he calls it an art in Posterior Analytics I, lect. 1² and Summa theologiae II–II, q. 47, a. 2, ad 3. Finally, in Opusc. 70, q. 5, a. 1, ad 3³ he says that “among the other sciences those are called arts which have not only cognition but some work that immediately belongs to reason itself, such as forming a syllogism and an utterance, counting,” and so on.

THE FIRST PART of the conclusion is proved because Logic has demonstrative acts; therefore it is a scientific habit.

The consequent is evident, and the antecedent is still more evident, because Logic resolves conclusions into indemonstrable first principles. For example, when it proves that contradictories cannot be true together from the principle “Everything either is or is not,” it shows that two contraries cannot be true together, since that would entail that two contradictories were true together; it shows that a syllogism in Darii concludes correctly, because “to be said of every” is perfectly preserved in it, and countless other cases.

THE SECOND PART is proved in the same way, because the definition of art applies to Logic: art is called “the right reason of things to be made.” Hence two things are required for art. First, on the side of matter that can be directed and formed, it must not be wholly determined but possess some indifference; otherwise it could not receive regulation and art, just as acts of seeing and hearing cannot be directed by art. Second, on the side of form, which functions as a directing rule, regulation must proceed by certain and determinate ways. If the means were not certain and determinate but contingent, they would be directed not by art but by prudence, which directs by deliberation rather than art, since it has no certain and determinate rules, but discretionary and prudential ones suited to the circumstances that arise, as St Thomas teaches in Summa theologiae II–II, q. 47, a. 2, ad 3. Not only external works, called “things to be made,” fall under the regulation of art—these are the concern of the so-called mechanical arts, since external works are more servile and subject to command—but also internal works, which are freer and less servile; hence the arts directing them are called liberal arts. In the actions of both kinds there is matter that can be directed by certain and determinate rules, because there is indifference as to whether they are done well or badly, with or without error.⁴

The second part of the stated conclusion is proved from this: the remote matter, or matter that can be directed by Logic, consists in cognitions or operations of the intellect, which, insofar as they attain objects, can proceed with or without error and thus have sufficient indifference to be directed and formed by right disposition and ordering. On the side of form, or rules by which Logic orders, it has certain, determinate and immutable rules, as is clear from what has been taught in the Summulae and what we shall teach in this work, especially in the books of the Posterior Analytics. Therefore Logic has everything required for the nature of an art, and at the same time is a science because of the immutable certainty of its regulation, although its remote matter is indifferent.

THE ARGUMENTS ARE ANSWERED.

Against the first part of the conclusion it is argued that Logic is a mode and instrument of knowing; therefore it is not a science.

The antecedent is a common saying and is taken from Aristotle, Metaphysics II, near the end⁵, and St Thomas, Opusc. 70, q. 5, a. 1, ad 2⁶, where he says that “Logic is not placed under Philosophy as a principal part, but as something subordinated to it, insofar as it supplies its instruments to speculation.” The consequent is proved because an instrument does not have the same primacy as its cause or effect, as is clear in the case of a saw, a brush, and other things, which are not of the same nature as the thing they make or the agent that moves them.

THE ANSWER IS that Logic is called a mode and instrument of knowing objectively, not formally. For it treats as its object the mode of knowing and the instruments necessary for the other sciences, such as syllogisms and propositions; on the side of this object it differs from the other sciences, because they treat things, while Logic treats the mode of knowing. Since the mode of knowing must be known before things, Aristotle therefore said it was absurd to investigate both at once. In the same way St Thomas said that Logic is not contained principally under Philosophy, but as something subordinated to it, namely, as concerning the mode of knowing things, which is a less principal object. The argument’s consequent is answered as follows: first, Logic is not an instrument of the other sciences but of the intellect itself, which uses Logic as an instrument for directing the other sciences. Thus it follows only that Logic is proportioned to the intellect, not to the sciences. Further, it is not incompatible for an instrument to be of the same nature as the thing effected, though this is not always necessary, as one hammer makes another.

Second, it is argued that it is probable that teaching Logic and using it are one and the same habit, as is said in the final article. Therefore the habit of Logic elicits acts of opinion, as is evident in Logic as used, which proceeds topically and probabilistically, as is clear from St Thomas, Metaphysics IV, lect. 4⁷ and Opusc. 70⁸. But a habit that elicits acts of opinion cannot be science. Therefore Logic is not science.

It is confirmed because a being of reason cannot specify a real science, since a being of reason is not per se knowable and consequently not per se scibile, nor does it have true causes through which it may be known or properties that may be known of it. But a being of reason is the formal object of Logic, as we shall say in the next article. Therefore Logic is not truly a science.

THE ANSWER IS that this argument will be treated below, in the final article. For now we say that Logic, insofar as it is used, has an opinionative act not by reason of its formal motive, since it does not rely on fallible and contingent principles, but by reason of the consequent effect: it directs a mode of proceeding opinionatively in topical and tentative disputation, which is not fully resolutive. Hence it has an opinionative act directive rather than elicitive; or, if it elicits one, it does so secondarily and not principally. It is not incompatible, then, for a scientific habit to have an opinionative act secondarily and consequentially, in relation to the topical and opinionative rules that it teaches scientifically.

The confirmation will also be answered in the next article, where we shall show that a being of reason has sufficient knowability and objective truth, grounded in reality and necessarily connected, as science requires—not because it has truth subjectively and transcendentally as a true being, but objectively, as the object of a science.

Finally, it is argued: the nature of art is incompatible with science; therefore one or the other does not apply to Logic.

The antecedent is proved: art deals with singular and contingent things and is in the opinionative part of the soul, as St Thomas says in Summa theologiae I–II, q. 57, a. 4, ad 2, whereas science concerns universals and necessary things and is in the demonstrative part. Likewise, art proceeds compositionally and practically, while science proceeds resolutively and speculatively. Hence St Thomas, Metaphysics I, lect. 1⁹, distinguishes art from speculative reason and places it in the practical part of the intellect.

It is confirmed because the liberal arts are called arts by a certain likeness, as St Thomas says in Summa theologiae I–II, q. 57, a. 3, ad 3. Therefore Logic is not simply and properly an art.

THE ANSWER IS that art is said to concern singular and contingent things on the side of its application to a work, or on the side of its remote matter, which has indifference—not on the side of the rules by which it directs, for these are certain, determinate and universal. Hence art is numbered among the intellectual virtues in Summa theologiae I–II, q. 57, although these do not deal with contingent truth but with what is necessary, to which falsity cannot adhere; otherwise they would not be virtues, as St Thomas teaches in Nicomachean Ethics VI, lect. 5¹⁰. Art is said to be in the opinionative part of the soul either on account of the mechanical arts, or because of its application to a work, or because of the indifference of its remote matter that can be directed—not on account of direction and regulation, in which respect art is an intellectual virtue, something that does not belong to an opinionative habit. Nor is it of the nature of art to proceed compositionally and practically; when its work is speculation, it directs not by composing but by resolving, as will be explained further below.¹¹¹² And when St Thomas distinguishes art from speculative reason, he is not speaking of liberal art but of that which is art in such a way that it is not science.

The confirmation is answered by saying that liberal arts are called arts by likeness on the side of matter that can be directed, not on the side of the directing reason. Since the matter of a liberal art is an internal work of reason, which is less servile, it is consequently less subject to the command and direction of art than the work of a mechanical art, which is wholly servile. Yet on the side of the directing rule, liberal and mechanical art apply univocally. In any case, since we do not say that Logic is an art in just any way, but a liberal art, it has the nature of art precisely in the way that applies to liberal arts.