NECESSITÀ. —
I. PHILOSOPHY
This is said 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, thinking, and acting, to which, in general, is opposed that which is in itself contingent, problematic, free, or that which in itself remains indeterminate.First of all, there is a metaphysical necessity, or necessity of being as such, which is immutability in the possession of being. In the realm of the possible, it is the necessity of essences as the indivisible and indissoluble belonging together of the principles that constitute them at their proper degree of being. In the realm of reality, metaphysical necessity is the impossibility of something not being
Moreover, metaphysical necessity must also be referred to the properties deriving from the form of the spiritual being: immortality, the activity of thought, free will, sociability, morality, and 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 respective sensibles, 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 arising in bodies from 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 supernatural divine gift and surpasses every capacity of the human intellect (ibid., suppl., 3ᵃ, q. 75, n. 3). Metaphysical necessity therefore embraces the entire sphere of 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 derives ultimate end (v.) and of the universal good, which is the object of the will, since once the good is known it cannot fail to be loved: the necessity of the end entails the necessity of the means indispensable for attaining that end (Sum. Theol., 1ᵃ-2ⁿᵈ, q. 10, n. 1).
Just as in reality the necessity of being is the absolute consistency deriving from the very principles of being, so in the sphere 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 noncontradiction, identity, the excluded middle, the whole and its parts...) called « principles per se nota », since 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). knowledge (v.) science (v.) as essence stands to its properties and the end to the means, insofar as they are the cause of the necessity of conclusions: consequently, in the strict sense, necessity belongs to the apodictic syllogism, which proceeds precisely 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 two opposed solutions to the problem itself: « Is pleasure to be desired or not? Is the world eternal or not? » (Topica, I, 11, 104 b 1).
At the foundation of the entire Aristotelian-Thomistic doctrine of necessity lies the presupposition of realism, namely that knowledge reflects the being of things and the quality of knowing. The synthesis of subject and predicate in judgment is necessary when the connection between substance and property is likewise necessary in nature; and whoever thinks otherwise, Aristotle emphatically observes, is lying (Met., IX, 10, 1051 b 2 ff.). 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 among three modes of knowing—apodictic or necessary, contingent, and problematic—corresponds 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 matters: « 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 » (Encyhl., § 178), and this is the judgment of necessity, that is, « of the identity of the content in its distinction », so that the distinction among judgments (categorical, hypothetical, and disjunctive) depends on the different way of realizing this identity in the single form of « totality » (ibid., § 177). Finally, for Hegel the « syllogism of necessity » is that 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). Hegel takes the opportunity to observe that it is in this perfect coincidence of form and content that the demonstration of the Absolute can alone be found, a demonstration first introduced, albeit imperfectly, in the so-called ontological argument of St. Anselm, whose sole defect is 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, according to Hegel, will be resolved only through thinking or dialectical consideration.
Necessity is therefore the principal modality of being and thought, and its theoretical structure depends upon the different orientation that, in the various philosophies, the relation between being and thought assumes.
II. THEOLOGY: RELATIVE OR HYPOTHETICAL NECESSITY
Since the reason why a thing cannot fail to be is different according as it is founded on its intrinsic causes (essence) or on its extrinsic causes (the necessity of attaining the end), one must consequently speak, in addition to 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 thing required, the end cannot in any way be attained. It is moral when, without the thing required, one could, absolutely speaking, attain the end, but in fact, given the external and internal difficulties, the end remains, practically, always or almost always unattainable. In the first case there is moral necessity stricte dicta; in the second case, moral necessity late dicta.
To physical necessity, also called absolute in the hypothetical order in which it exists (cf. First Vatican Council, sess. III, chap. 2 [Denz-U, 1786], and can. 3 [Denz-U, 1808]), corresponds physical incapacity, which arises either from the very nature of the faculty, which is unequal to the act—for example, sight is physically incapable of perceiving sounds—or from the absence of some external condition sine qua non for the act—for example, without light and the proper distance, sight is physically incapable of perceiving colors. To moral necessity, which must not be confused with ethical necessity, signifying conformity to the supreme rule of action (v. mo-
RALITÀ), corresponds moral incapacity (v. INCOMODO), which exists when the faculty, although physically capable of such an act and of such an end, nevertheless does not attain it because of impediments that are ordinarily insurmountable (cf. Sum. Theol., 1°, q. 82, n. 1). Thus, when it is affirmed that, for a suitable knowledge of natural religion, Revelation is necessary for the human race by hypothetical moral necessity, it is meant that all normal human beings, individually and collectively, possess within themselves the physical capacity to know the whole body of doctrines and religious duties belonging to the natural order; nevertheless, in fact, given all the difficulties and all the obstacles, almost the whole of humanity 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 objectively supernatural truths, for example the Mysteries, or to perform any salutary act, that is, one meriting eternal life, Grace as an internal gift is required physically, absolutely, it is meant that the natural faculties of man, intellect and will, are physically incapable of performing such acts belonging to the supernatural order, absolutely transcendent to man; he therefore needs Grace, a divine gift, which is incorporated into man as a new principle of activity, strengthening, purifying, and elevating the human faculties to the supernatural order (cf. Conc. Carth., can. 5 [Denz-U, 105], Conc. Araus. II, cann. 6-7 [Denz-U, 179-80]; Conc. Trid., sess. VI, cann. 1, 2, 3, [Denz-U, 811-13]).
In addition to the foregoing distinction between physical moral or absolute necessity, there is the distinction 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 in itself or by virtue of the divine plan—that is, by God’s positive ordination—it is the sole means of obtaining eternal life and the aids necessary for attaining it, so that its omission, even involuntary, renders salvation impossible.
In the first case, such necessity is absolute, and, without the thing required, the end cannot in any way be attained; that is, it cannot be supplied by anything else. Such are faith and sanctifying Grace. In the second case, however, the thing required is only hypothetically necessary: that is, it is the sole ordinary means of salvation, and in the event of impossibility it can be replaced by an extraordinary means. Such are Baptism by water and 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 divine precept, so that its gravely culpable omission alone prevents salvation, never an inculpable omission. Such is 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 one to the end also obliges one to the necessary means.
N. also has the meaning of need, that is, a lack of the things necessary for life. In this sense it admits of degrees: it may be extreme, grave, or ordinary; and according to the various degrees, it gives the person subject to it more or less strict rights to the assistance of his fellow human beings. N. finally has the meaning of constraint, not a physical, external constraint, which then takes the name of coercion, but an inner impulse or stimulus. In this case necessity is regarded as a force that cannot be resisted and that inevitably carries the will along: one is then said to act in a state of necessity.
V. FORZA MAGGIORE; LIBERTÀ.