Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

Here we are speaking of premises in a demonstrative syllogism that convinces the intellect and necessitates it by the granting of the premises.

But in a probable syllogism, once the premises are granted and the validity of the inference stands, is the intellect necessitated to assent to the conclusion? I answer briefly: it necessitates the intellect by the force of the inference, not by the force of the truth of what is inferred. Therefore it does not necessitate it absolutely. For although, once the premises are granted and rightly arranged, the intellect cannot dissent if it proceeds to the conclusion, in probable matter it can refrain from proceeding to the conclusion and instead go back to examine the premises; since they are probable, it can dissent from them. This does not apply in demonstration, in which the intellect must not only proceed to the conclusion but also cannot go back. Thus St. Thomas teaches in Summa theologiae I, q. 82, art. 2, that the intellect does not assent necessarily to contingent propositions whose removal does not entail the removal of their principles. Therefore, since even with the premises posited the intellect sees that removing them does not remove the prior principles, it can go back from the premises and thus is not necessitated absolutely. It is nevertheless bound to assent to the probability itself, if it is evident, though not to its truth.

Thus, for the POINT OF THE PRESENT DIFFICULTY to become clear, we must assume the familiar distinction between necessity with respect to specification and necessity with respect to exercise. The first concerns the species of the act, the second its eliciting. The first is therefore explained conditionally: if the power elicits an act, it can elicit only an act of that species; yet it can absolutely refrain from eliciting one. The second, by contrast, is explained absolutely, because in fact the power is bound to elicit the act. A twofold freedom corresponds to this twofold necessity: one with respect to specification, also called freedom of contrariety, because it can concern specifically contrary acts, for example, hatred and love; the other with respect to exercise, called freedom of contradiction, which concerns only eliciting or not eliciting an act.

When we ask here whether the intellect is necessitated to assent to the conclusion, we are speaking of formal, not virtual, assent. Virtual assent is present in the premises, in which the conclusion is virtually contained; thus virtual assent to the conclusion is the same as formal assent to the principles as disposing us toward it.

In the present case, then, it is beyond dispute that, when evident premises stand, the intellect is necessitated with respect to specification to assent to the conclusion. The reason is that there can be no dissent concerning the true as true, nor assent concerning the false; otherwise someone could assent to two contradictories, if one could assent to or dissent from truth equally, and likewise in the case of falsity. But when true and evident premises are posited, the conclusion cannot fail to be true; otherwise a true antecedent could have a false consequent. Therefore such a conclusion is no more capable of dissent than of falsity; consequently, it necessitates assent. The difficulty that remains, then, concerns necessity with respect to exercise.

In this regard, some think that, when the premises are posited, the intellect is not necessitated with respect to exercise concerning such a conclusion, but can be impeded by the will. This can be explained in two ways: first, the will could directly suspend the intellect so that it does not proceed to assent to the conclusion, just as it suspends the hand from moving; second, it could do so indirectly by diverting the intellect to another cognition or preventing it from attending to the premises. Others teach without qualification that, once assent to the premises stands, the intellect is necessitated with respect to exercise.

NEVERTHELESS, LET THERE BE ONE CONCLUSION: When evident premises stand, the intellect is directly necessitated with respect to exercise to assent to the conclusion. The will can, however, impede it indirectly, because the intellect is not necessitated to attend to and consider the premises.

This is the common view and is drawn from St. Thomas, Summa theologiae I, q. 82, art. 2, where he says that the intellect naturally adheres by necessity to principles and conclusions having a necessary connection with them. He teaches this more clearly in Summa theologiae I–II, q. 17, art. 6, where he says: “An act of reason can be considered in two ways. In one way, with respect to the exercise of the act, as when someone is commanded to attend and use reason; in this way an act of reason can be commanded. In another way, with respect to the object, in relation to which two acts of reason are considered. First, reason apprehends the truth about something; this is not in our power, for it occurs through the power of some light, natural or supernatural. Therefore, in this respect, the act of reason is not in our power. Another act of reason occurs when it assents to what it apprehends. If, then, what is apprehended is such that the intellect naturally assents to it, as with first principles, assent or dissent concerning such things is not in our power but is subject to the order of nature. There are, however, some things apprehended that do not so convince the intellect that it cannot assent or dissent, or at least suspend assent and dissent for some reason; in such cases assent or dissent itself is in our power.” Thus St. Thomas. Here he distinguishes two kinds of exercise: one concerning the application of attention to this or that object, and another concerning the application of assent. The first application lies in the will's power, so that it can attend to or think about the premises; the second application, with respect to assent itself, is not in the will's power except with respect to objects that do not convince the intellect. Therefore, with respect to objects that convince and necessitate the intellect, it cannot do this—not only cannot it dissent or assent at will, which is freedom of contrariety, but it cannot suspend or refrain from suspending assent, which is necessity of exercise, since St. Thomas says that in this respect it is not in our power; the exercise of an act, however, is what depends on our power.

From this it follows that the will cannot directly impede the exercise of assent to an evident conclusion once assent to the premises is posited. For the will cannot impede the vision of an object when the light illuminating it and the eyes open are posited, as experience itself makes clear and reason plainly proves: in that case all the causes are natural agents that cannot be impeded by the will. For the light itself naturally manifests and illuminates the object, while the cognitive power naturally operates in cognizing an object sufficiently presented. It is clear that evident premises, rightly arranged, illuminate and manifest the conclusion as light does colors. The intellect itself is also a non-free power, operating naturally with respect to an object sufficiently presented, that is, illuminated. Therefore, when such illumination stands and the power itself is awake and attending, it necessitates with respect to exercise and cannot be impeded by the will, just as the will cannot keep open eyes from seeing.

The will can, however, divert the intellect indirectly from assent to the conclusion, because it can divert the intellect from thinking about the premises, just as one can turn away from or close one's eyes to something plainly visible. If assent to the premises is relaxed or omitted, or one does not consider how they are arranged for inferring the conclusion, illumination concerning the conclusion does not follow.

From what has been said you will understand how the Philosopher's statement here is to be understood: “The major is known earlier in time than the conclusion, but the minor is known at the same time as the conclusion.” He is speaking of the major considered in itself and separately. Since it is the more universal proposition and is not subsumed under another but is itself assumed, it can be known separately and by itself, and therefore earlier in time. But if the minor is considered formally as a minor, that is, as inferior and subsumed under the major and determining it to influence the conclusion determinately, it cannot be understood unless the conclusion is understood at the same time, provided that it is subsumed and arranged under the major. This is understood not only negatively—that nothing intervenes between the cognition of the minor and of the conclusion—for that is evident, since the minor is the last part among the premises and so the immediate part joined to it must be the inferred conclusion, which is something outside the premises. Rather, it is understood positively as well: in the same instant that the minor is cognized as minor, assent to the conclusion is deduced, as St. Thomas asserts in his commentary on Posterior Analytics I, lect. 2¹. For once cognition of the minor is posited formally as coordinated and subordinated to the major, and thus the validity of the inference is presupposed as known, a sufficient and necessitating light for manifesting the conclusion is thereby posited. The conclusion is manifested by no other light than the inferential light contained in the premises. Illumination takes place in an instant—much more so in the case of spiritual light than corporeal light, because spiritual light is more effective and perfect and less dependent on the body. Therefore, in the same instant that the light of the premises is posited, ultimately determined by the minor, assent to the conclusion is posited as proceeding from a cause that is unimpeded and acts instantaneously, just as was said of illumination.

You will say: The intellect is a limited power and cannot elicit several acts at the same time, or at least can elicit only a definite and limited number. Therefore, it could be that assenting to the minor is the last act the intellect can elicit by its natural power; consequently, it could not then elicit assent to the conclusion.

The reply is that in such a case, if the intellect cannot relax any of its preceding cognitions, either because they necessitate the intellect or because the will does not wish it to withdraw from them, the intellect will not produce formal assent to the conclusion because of the impediment and limitation of its power. Here, however, we are speaking of an unimpeded cause. This is compatible with the intellect being necessitated simply by the light of the premises, just as fire necessitates heating and the eye necessitates seeing, provided there is no impediment and its power does not exceed its capacity to act.

As for what some further think, in a stricter sense, namely, that the minor and conclusion can be cognized not only simultaneously but also in one indivisible cognition of principle and conclusion, this is proper only to angelic light, which by one act accomplishes all that our discursive reasoning accomplishes through many acts. By discursive light this cannot happen; a human being would have to be raised divinely above the connatural mode of human cognition, as is usually admitted in the case of Christ's infused knowledge. If, however, we speak of virtual cognition of the conclusion, it is clear that it is cognized in the premises by the same act as the premises.

THE ARGUMENTS ARE ANSWERED.

First it is argued: The will is not necessitated by some particular good that does not pertain to its proper being. But assent to the conclusion, even after assent to the premises, is a particular good, according to St. Thomas's rule in Summa theologiae I–II, q. 9, art. 1, ad 3, that the very truth which is the intellect's perfection is contained under the universal good as a particular good. Therefore, the will is not necessitated by it with respect to exercise.

It is confirmed: If the will necessitates assent to an evident speculative conclusion, it also necessitates assent to an evident practical conclusion, such as: “Do not do to another what you would not want done to yourself; but you do not want to be robbed; therefore you ought not to rob another.” Yet the will is not necessitated to assent to this practical conclusion, since it sometimes does the opposite. Therefore, and so on.

THE REPLY follows the teaching given above from St. Thomas concerning the two kinds of exercise: to apprehend principles, to assent to them, or to assent to conclusions necessarily deduced from them. With respect to the first, the will is free and can draw the intellect back so that it does not think about the principles; thus it can indirectly cease from assent to the conclusion and fail to continue it by introducing an impediment. The will cannot impede the second kind of exercise, once assent to the premises is supposed, in propositions that convince the intellect, as we showed above from St. Thomas.

To the confirmation, the reply is that a practical syllogism, insofar as it is practical and effectively moves the will with respect to exercise, does not necessitate the will. First, because the will can divert the intellect's cognition from the right proposition of the principles, just as it can in speculative matters, in accord with Psalm 9²: “Your judgments are removed from his sight.” If it does not divert the intellect from the right proposition of the principles, it will be necessitated to the practical conclusion by supposition and in a qualified sense. Second, because correctly arranged practical principles necessarily conclude only that something is due to be done, or is fitting according to law—not always that it is appetible. In exercise, appetibility is proposed with indifference unless God is clearly seen. In this respect, therefore, a practical syllogism does not conclude by compelling assent but by proposing indifferently; the will follows the appetibility that is proposed here and now, not merely what is fitting to reason according to law.

Second it is argued, that even once assent to the premises is posited, the intellect needs a habit in order to assent to a scientific conclusion, since science concerns that conclusion. Therefore the intellect retains some indifference toward such assent even when the premises are posited. For if it had none, it would generate no habit: where there is total determination of a power, no habit that removes its indifference is given; but where there is some indifference, there is not complete necessity.

It is confirmed: If two conclusions are inferred from necessary premises, one direct and the other indirect—as when Baralipton is inferred from premises in Barbara—the intellect would be necessitated to both conclusions. This is false, because one demonstration elicits and requires only one conclusion; therefore the will determines which one it will choose. Finally, if, once the premises are posited, the intellect is necessitated to exercise assent to the conclusion, by the same reasoning it will be necessitated to continue assenting while the same premises remain. Thus, once a demonstration has been made, it could not cease.

THE REPLY is that a scientific habit does not reach only the inferred conclusion, on the supposition of assent to the premises and the validity of the inference; it also reaches the premises as inferential and their arrangement. All of this requires a habit, so that a demonstration can be elicited not only when it is first made but also later. It is true, however, that if we attend only to the inference of the conclusion after assent to the premises and their correct arrangement, this alone would not require a habit overcoming some difficulty.

To the confirmation, the reply is that when two conclusions are inferred from the premises, they are not both inferred equally immediately; the indirect conclusion is inferred through some conversion or transformation of a proposition. Hence, just as the intellect is necessitated to assent to the first conclusion only when the premises are rightly arranged, not in any manner whatsoever, so it will not be necessitated to the indirect conclusion with equal immediacy, but only after the stated transformation or conversion has been made. As for continuation of assent, when assent to the premises is continued, assent to the conclusion will also continue; but the intellect can be diverted from thinking about the premises and thus cease assenting to the conclusion.