Necessity

NECESSITY. - I. PHILOSOPHY. - It is predicated of everything that in some order (ontological, physical, logical and moral) "cannot be otherwise" (τὸ μὴ ἐνδεχόμενον ἄλλως ἔχειν ἀναγκαῖν φάμεν οὕτως ἔχειν: Met., IV, 5, 1015 a 34; cf. Post. Anal., II, 33, 38 b 30). Necessity therefore expresses a "modality" of being, of thinking and of acting, to which there is generally opposed what is in itself contingent, problematic, free, or rather what in itself remains undetermined.

There is first of all a metaphysical necessity, or necessity of being as such, which is immutability in the possession of being. In the field of possibles it is the necessity of essences as the indivisible and indissoluble belonging together of the principles that constitute them in their own degree of being. In the field of reality metaphysical necessity is the impossibility of something not to exist and constitutes the most perfect grade of the real, to which corruptibility and contingency (v.) are opposed; it belongs properly to spiritual beings insofar as the absolute immateriality of the essence (v.) removes them from every principle of corruption and therefore of loss of being. Metaphysical necessity in the perfect sense belongs to God, who is Pure Act, Being by essence. Nevertheless St. Thomas maintains that spiritual creatures too enjoy an absolute metaphysical necessity, albeit created: « Sunt enim quaedam in rebus creatis, quae simpliciter et absolute necesse est esse in quibus non est possibilitas ad non esse... Illae res in quibus non est materia, non habent potentiam ad non esse: eas igitur absolute et simpliciter necesse est esse » (C. Gent., II, 30; cf. Aristotle, Met., V, 5, 1015 b 10). On this doctrine of participated metaphysical necessity is founded the requirement of the «per se necessarium» that sustains the third way of demonstrating the existence of God (Sum. Theol., 1ᵃ, q. 2, n. 3).

Furthermore, metaphysical necessity must also be referred to the properties deriving from the form of spiritual being: immortality, the activity of thought, free will, sociality, morality, religiosity. In an even more general sense, it is by metaphysical necessity that every power is specified by its proper object: the eye by colors and the other senses by their proper sensible, the appetite by the good, the intellect by the true (cf. Sum. Theol., 1ᵃ, q. 77, n. 3). By contrast there is a negative metaphysical necessity that comes to bodies from the side of matter, namely their corruptibility, since they are composed of contrary elements that therefore tend to separate: for this reason the immortality that will be granted to the human body at the final resurrection is considered a preternatural divine gift and surpasses every capacity of the human intellect (ibid., suppl., 3ᵃ, q. 75, n. 3). Metaphysical necessity therefore embraces the whole sphere of the essence: « Necessitas absoluta competit rei secundum id quod est intimum et proximum ei: sive sit forma, sive materia sive ipsa rei essentia » (In V Met., lect. 6; ed. Cathala, Turin 1950, n. 833). From the final cause comes the necessity of the ultimate end (v.) and of the universal good, which is the object of the will, since the good, once known, cannot but be loved: the necessity of the end carries with it the necessity of the means that are indispensable for the attainment of the end itself (Sum. Theol., 1ᵃ-2ⁿᵈ, q. 10, n. 1).

Just as in reality the necessity of being is the absolute consistency that comes from the very principles of being, so in the domain of thought (logical necessity) necessity is the «coherence» or absolute connection between principles and conclusions. Logical necessity therefore belongs first of all to the first principles (of non-contradiction, of identity, of excluded middle, of whole and parts...) called «principia per se nota» insofar as their evidence is immediate for anyone who grasps the meaning of the respective terms (cf. Sum. Theol., 1ᵃ, q. 2, n. 1; Aristotle, Anal. Pr., I, 2, 25 a 1). The first principles stand to knowledge (v.) and to science (v.) as the essence stands to its properties and the end to the means, insofar as they are the cause of the necessity of the conclusions: therefore in a rigorous sense necessity belongs to the apodictic syllogism, which precisely proceeds from necessary principles (Anal. Post., II, 6, 74 b 15 ff.). In this sense necessary knowledge is opposed to contingent knowledge and to problematic or dialectical knowledge, which leaves open a twofold opposed solution of the problem itself: «Pleasure, should it be desired or not? Is the world eternal or not?» (Topica, I, 11, 104 b 1).

At the foundation of the whole Aristotelian-Thomistic doctrine of necessity lies the presupposition of realism, that knowledge mirrors the being of things and the quality of knowing. The synthesis of subject and predicate in the judgment is necessary when the connection of substance and property is likewise necessary in nature, and whoever thinks otherwise, Aristotle observes energetically, lies (Met., IX, 10, 1051 b 2 ff.). And St. Thomas echoes this in his commentary: « Manifestum est quod dispositio rei est causa veritatis in opinione et oratione... Oportet veritatem et falsitatem quae est in opinione vel oratione reduci ad dispositionem rei sicut ad causam » (In IX Met., lect. 11, nn. 1897-98).

For Aristotle, therefore, the distinction of three modes of knowing: apodictic or necessary, contingent and problematic, is related to three different modes inherent in the structure of things themselves, in which consists the fundamental ontological truth of which logical truth is the expression in language and in the life of thought (cf. De Interpr., 12, 21 a 34 ff.). Similarly for St. Thomas necessity in the processes of thought derives from things themselves, which guide the course of the mind and govern its affirmations and negations in contingent or necessary matter: « Non enim propter nostrum affirmare vel negare mutatur cursus rerum, ut sit aliquid vel non sit, quia veritas nostrae enunciationis non est causa existentiae rerum sed potius e converso » (In Periherm., lect. 14; ed. Leonina, I, p. 65 b). According to Hegel, on the other hand, «the judgment of the concept has the concept as its content» (Encykl., § 178), and this is the judgment of necessity, that is, «of the identity of the content in its distinction,» so that the distinction of judgments (categorical, hypothetical and disjunctive) depends on the different way of realizing this identity in the single form of «totality» (ibid., § 177). The «syllogism of necessity» finally is for Hegel the one in which «each of the moments has shown itself as the totality of the moments, or expresses the totality returned into itself whose differences are likewise this totality» (ibid., § 193). And Hegel takes the occasion to observe that it is in this perfect coincidence of form and content that one can alone have the demonstration of the Absolute, first found, albeit imperfectly, in the so-called ontological argument of St. Anselm, whose defect is only that the identity of essence and existence in the Absolute is presupposed, that is, is taken only as unity in itself: a defect that remains also in Descartes and Spinoza and that will be resolved only, according to Hegel, by means of thinking or dialectical consideration.

Necessity is therefore the principal modality of being and of thought, and its theoretical structure is a function of the different orientation that the relationship between being and thought assumes in the various philosophies.

Cornelio Fabro

II. THEOLOGY: RELATIVE OR HYPOTHETICAL NECESSITY

Since the reason why a thing cannot but be is different according as it is founded on the intrinsic causes of that thing (essence), or on extrinsic causes (necessity of attaining the end), one must consequently speak, besides absolute or metaphysical necessity (founded on the intrinsic causes of the thing), of relative or hypothetical necessity (deduced from the end to be attained).

The latter is physical when, without the required thing, the end cannot be attained in any way. It is moral when, without the required thing, the end could, absolutely speaking, be attained, but in fact, given external and internal difficulties, the end remains, practically, always or almost always unattainable. In the first case there is necessity stricte dicta; in the second case necessity late dicta.

To physical necessity, also called absolute in the hypothetical order in which it exists (cf. Vatican Council, sess. III, cap. 2 [Denz-U, 1786], and can. 3 [Denz-U, 1808]), there corresponds physical impotence, which arises either from the very nature of the faculty being unequal to the act — for example, sight is physically incapable of perceiving sounds — or from the lack of some external condition sine qua non for the act — for example, without light and due distance sight is physically incapable of perceiving colors. To moral necessity, which is not to be confused with ethical necessity, which denotes conformity to the supreme rule of action (v. MORALITY), there corresponds moral impotence (v. INCOMMODITY), which occurs when the faculty, although physically capable of such an act and such an end, nevertheless does not attain it because of impediments that are usually insuperable (cf. Sum. Theol., 1ª, q. 82, n. 1). Thus, when it is affirmed that for a fitting knowledge of natural religion Revelation is necessary, for the human race, by hypothetical moral necessity, what is meant is that all and each normal man has within himself the physical capacity to know the complex of doctrines and religious duties of the natural order; yet, in fact, given all the difficulties and all the obstacles, almost the totality will never attain this knowledge by its own powers alone; which is to say: it is morally incapable. When, on the other hand, it is said that in order to know truths that are objectively supernatural, for example, the Mysteries, or to perform any salutary act, that is, one meritorious of eternal life, Grace as an internal gift is required physically, absolutely, what is meant is that man's natural faculties, intellect and will, are physically incapable of performing such acts of a supernatural order, absolutely transcendent to man, who therefore needs Grace, a divine gift, which is inserted into man as a new principle of activity, which strengthens, purifies and elevates the human faculties to the supernatural order (cf. Council of Carthage, can. 5 [Denz-U, 105]; Council of Orange II, cann. 6-7 [Denz-U, 179-80]; Council of Trent, sess. VI, cann. 1, 2, 3 [Denz-U, 811-13]).

Besides the preceding distinction between moral, physical or absolute necessity, there is that between necessity of means and necessity of precept, when the end to be attained is specifically eternal salvation. A thing is said to be necessary by necessity of means when either by itself, or by virtue of the divine plan, that is, by positive ordinance of God, it is the only means of obtaining eternal life and the helps necessary to attain it, so that its omission, even involuntary, places one in the impossibility of being saved.

In the first case such a necessity is absolute, and, without the required thing, the end cannot be attained in any way, that is, it cannot be supplied by another thing. Thus faith, sanctifying Grace. In the second case, on the other hand, the required thing is only hypothetically necessary, that is, it is the only ordinary means for salvation, and in case of impossibility it can be supplied by an extraordinary means: thus the Baptism of water, the Sacrament of Penance for sinners. A thing is said to be necessary by necessity of precept when it is required for salvation, but only by a divine precept, so that only a gravely culpable omission of it impedes salvation, never a blameless omission. Thus the reception of Extreme Unction. Finally, as is clear, those things that are necessary by necessity of means are also necessary by necessity of precept, since whoever obliges to the end also obliges to the necessary means.

Necessity also has the meaning of need, that is, of lack of the things necessary for life. In this sense it admits of degrees: it can be extreme, grave, ordinary; and according to the various degrees it gives to the one subject to it more or less strict rights to the assistance of his fellow men. Necessity finally has the meaning of constraint, not physical, exterior, which then takes the name of coercion, but of impulse, interior stimulus. Necessity in this case is considered as a force, which cannot be resisted, and which inevitably drags the will along: one then says that a person acts in a state of necessity.

V. FORCE MAJEURE; LIBERTY.

Giacinto Ameri