Collected Works

Arguments concerning logic. Namely, whether propositions that are not universal are vain and superfluous.

The way in which the Stoics wished logic to be a part of philosophy. For they divided universal philosophy into practical, speculative, and instrumental. But the Academics said that logic in itself is not a part of philosophy: but is rather a tool, as an instrument. The Peripatetics, however, agree with this, that it is an instrument and a part, just as a tool is an instrument of the human body.

of the parts of philosophy. We shall add the exposition later. ¶ And hence, the deceptions that arise regarding such a question are vain and superfluous: vain, because there is no opposition in these terms; for each one of them understands something different by philosophy. Superfluous, indeed, because concern regarding such matters provides no benefit. ¶ And this species of speculation is called logic, which is the contemplation of the aforementioned things through which one arrives at the cognition of the unknown and of that which follows from them, from the fact that they are useful for this purpose alone.

a What logic is.

b The perfection of man lies in that he is to know the truth for its own sake and the good, so that he may act.

the perfection of man
Since, from the fact that man possesses intellect (as will be shown later in its proper place), it was his [nature] to know the truth for its own sake and the good for the sake of doing it and acquiring it; yet the first nature and the beginning of man was only slightly useful for this, and whatever more he has of this is not had except by acquisition; and this acquisition is the acquisition of the unknown if the one acquiring the unknown has [it as] known.

c The necessity of logic.

ᶜ Then it is necessary that man first begins to know how the unknown is had through the known; and what the disposition of known things is, and their order in themselves, so that he may progress toward the cognition of the unknown. That is, [either] when they have been distinguished in the mind, as is said; and the forms of those known things have rested in him in the order in which they ought: so that the mind may be moved from them to the unknown being sought, and recognize it.

A thing is known in two ways. One way by simple apprehension. The other by belief or doubt.

¶ Just as a thing is known in two ways: one, so that it is understood only, such that its name—by which it is called—represents its intent to the mind (even though there is no truth or falsehood there, just as when "man" is said, or when it is said "do this"; therefore, when you have grasped the intention of that which is said to you, you have already understood).

¶ The other, as when there is belief in the intellect: just as when it is said to you that "every whiteness is an accident," from which you will not only understand the intention of this phrase, but also believe that it is so.

Doubt is not about that which is not understood.

But when you have doubted whether it is so or not, you have already understood what was said to you; for you do not doubt about that which you do not understand, nor about that which you do not know; yet you have not yet believed it.

Belief presupposes understanding, and not the other way around.

For all belief is with understanding and is not sought [otherwise]. The intellect, in this intention, helps you to work in the mind with the forms of this composite and those from which it is composed: just as [of] whiteness and accident. But belief regarding that which is held in the mind is a comparison of this form to that which it accompanies.

A thing is unknown in two ways. Namely, by simple understanding. The other way by belief.

¶ But measurement original: "mētiri" — here likely referring to the process of evaluation or syllogistic reasoning differs from this, just as a thing is unknown in two ways: one according to the intellect, the other according to belief. But each of these is not made known except by acquiring it. It is not acquired, however, except from something previously known and from the affection and property which that known thing has, because of which the mind is moved from the knowledge of the known to the knowing of the unknown.

Things that are usually provided to know that whose understanding is unknown, and why they do not agree in one common definition.

¶ Therefore, here is something that usually is useful for knowing that whose intellect is unknown; it is not, however, a custom that the intention containing this—according to the fact that its knowledge is useful for the knowledge of understanding—is called "common"; or perhaps it has not yet reached us as one. For one of these is definition, another is description, and another is example, and another is that which is a sign, and another is a name, as will be declared later. But that in which they agree does not have a common name. That which is opposed to it, however, is made known; then through that, the other is known in the manner of believing it.

The division of reason.

¶ Whatever it may be, it is called [by a name]. One reason is a syllogism, another is induction, and another is analogy, and another is something else.

The end of logic.

¶ But the end of the science of logic is

to be useful entirely for knowing these two things only: that is, so that a man may know how the phrase giving understanding—which brings the knowledge of the truth of the essence of a thing—ought to be; and what kind is the one which also shows it, even though through it one may not arrive at the truth of its essence; and what kind is the vicious [phrase] which seems to do this but does not; and also so that a man may know what kind of phrase is that which makes faith original: "fidem" — here meaning 'belief' or 'credence' in a necessary truth, so that it cannot be weakened; and what kind is the one making faith in verisimilitude; and how it is of such a mode that it is thought to be one of the two modes, when it is not so, but is false; and what kind is such that it compels one to opine and bends the mind, and suffices without the most certain faith; and what kind is the phrase working in the soul for that which faith works—namely, negation and affirmation, and prohibition and expansion, and constriction—not from the fact that it makes faith, but from the fact that it makes verisimilitude. For many verisimilitudes are compared in this way, that faith works.

¶ For when you have said that honey is a yellow humor that nature receives, who would not believe it in no way? Or would it thus deform if there were faith there, or a likeness which is almost faith? And what are the differences between those modes, and why were they so?

¶ Whoever, however, learns this doctrine, so that through it he may tend toward these two intentions, needs propositions through which he comes into the cognition of these two intentions; and this doctrine is logic.

¶ It happens, however, to a man that sometimes a definition is manifested to him naturally, giving him understanding, and a reason making faith; and from this, the thing is not doctrinal, nor is it so true that it does not sometimes fail.

The necessity of logic.

¶ But if nature and intellect suffice for this without doctrine, as happens in many, there would not occur in opinions such great diversity and contradiction; nor would one man sometimes contradict himself, and sometimes not, when he proceeded according to his own intellect.

That nature and human intellect do not suffice without doctrine to acquire a definition giving understanding to itself and a reason making faith.

Human nature, however, is insufficient for this—that it does not acquire doctrine—just as it is insufficient in many other reasons; for it would often happen that it makes a correct [judgment], just as the correct shot of a blind man.

¶ But when doctrine is acquired with all human virtue, it is not, however, sufficient for itself everywhere, so that it does not fail in any way; for sometimes one declines from doctrine in many dispositions.

By what causes doctrine does not prevent us from error.

¶ For it is not in itself a thing holding back and prohibiting from error, for many reasons. First, because the agent has not attained the doctrine perfectly. Second, because he has affected it, but for the most part he omits them and abounds in his own sense. Third, because it often happens that one is lazy to exercise it and omits it.

Note the utility of doctrine.

¶ But although it may be so, a student of science, when he has had it and exercised it, not as much error will occur to him as to those who do not have it.

Less error occurs in doctrine the more we exercise ourselves in it.

¶ And because of this, when he has often exercised the action of his doctrine, he will be able to correct error wherever it may be in the final state of confusion.

¶ And when it is so, error will not occur to him regarding the occupations of his doctrine, which he more often studies to exercise, just as error occurs in neglected things.

¶ For man, in his conceptions, has some things about which he intends more, and others about which he intends less. But having the doctrine of logic, he can study to certify the truth of those things by frequenting the intention of his action, according to his rule.

Through doctrinal exercise one arrives at the security against error.

For through doctrinal exercise, one arrives at security against error, just as he who often aggregates the parts of some number so that he may be more certain of the question because of the retention of the entire sum.

He concludes the necessity of logic.

¶ This doctrine, therefore, is necessary for the perfection of man; for he is not supported by a property through which he is excused from inquiry.