NATURE (IN PHILOSOPHY)

From the Latin natura (Gr. φύσις), a term with many related meanings in philosophy and with extensive applications in theology. Among philosophers it is commonly taken to mean the essence of a thing as this is the source of its properties or operations; more strictly, however, it is a primary and per se principle of motion and rest that is found in natural things as opposed to artifacts. It is sometimes used in the more restricted sense of human nature, for which meaning see man. Theologians use the term in opposition to grace or to supernature, particularly when discussing human nature, and in opposition to person, particularly in Trinitarian theology and Christology.

Since nature is the proper subject of the philosophy of nature, the major emphasis in this article is on nature as studied in natural philosophy. Topics treated include the primary meanings of the concept, its development among the Greeks, modifications in it occasioned by the rise of modern science, an Aristotelian analysis of its meaning in natural philosophy, and various secondary meanings.

Primary Meanings. On Nature (Περὶ φύσεως) is the title under which the writings of the pre-Socratics have been handed down to posterity. Some doubt exists as to what precisely was the first meaning, but it is generally admitted that at least an early and important use of the term φύσις was to designate the primordial stuff or underlying substratum persisting through all change. It is likely that the early Ionian philosophers imagined the world as developing in an orderly fashion from within, somewhat as a living being, and hence the primary substance would have been viewed, though indistinctly, as a source of activity. Thus φύσις was an intrinsic principle that accounted for the ceaseless change or becoming of things. Moreover, the very process of becoming, it seems, was itself called φύσις, a term that is etymologically related to φύω, to grow (cf. Lat. natura and nascor ). Finally, at some later date the term was applied to the changing things themselves taken in their totality. This is possibly the most common sense of nature in modern usage and was probably the meaning of φύσις intended in the title Περί φύσεως. (For Aristotle's account of the etymology and the meanings of φύσις, see Meta. 1014b 16–1015a19.)

Greek Development. The attempt of the Ionians of the 6th century b.c. to explain all becoming in terms of one material principle (e.g., water or air or fire) reached its logical conclusion in parmenides with the very denial of nature as process. For Parmenides all being must be one and exclude all nonbeing; as such it is perfectly immutable, and only as such is it knowable; all change is but sensory illusion. After Parmenides, there was an attempt to reconcile being, stable object of intellect, with the becoming of sensory experience. Fundamental reality remained immutable; it was, however, multiple: the four elements of empedocles; the "seeds," infinite in number, of anaxagoras; the atoms of Leucippus and democritus. These particles, in motion, combined and separated, and as such were principles of change and of a multiplicity of changing compounds. The atomists, with their homogeneous particles differing only in size and shape, interpreted all change in terms of movement in space ("void") and all sensible qualities, such as color, in terms of quantitative differences (see atomism). They have been considered as forerunners to modern science. So too have the Pythagoreans, who, from the 6th century b.c., had been seeking to explain the world in the light of numbers.

The claim to find the ultimate explanation of reality in the random motions of corporeal elements, i.e., in nature and chance, was strongly opposed by plato. If nature means the primary source of becoming, what is truly nature, for him, could only be what is really first, and that is intelligence and art. Thus, with Plato, nature in the commonly accepted sense gave way to divine soul, and chance to divine direction (Laws 888E–899D). Finality, introduced as conscious design, was lodged in a principle (soul) distinct from the purely corporeal. Likewise, the intelligibility of sensible bodies was to be sought beyond them, in the changeless, purely intelligible Ideas, of which they are imperfect imitations (Phaedo; Rep. 449–540). The order of the sensible world could be seen, too, in terms of the a priori principles of pure number. As for the changing imitations considered in themselves, of these there could be no science, but only a likely account.

Nature was reinstated as a true principle and a real source of explanation within the material universe by aristotle, who thus restored the philosophy of nature to the rank of a science (scientia). Aristotle continued the naturalist tradition of the pre-Socratics, his science being qualitative rather than mathematical, empirical rather than rationalist. It was far from being a mere return, however. After Plato there was form to be reckoned with. In Aristotle the natural world becomes intelligible in itself only because nature is identified with form in matter—with form now seen as the actuality of matter—even more properly than with matter itself (see matter and form). This form becomes the origin of activity, and matter, considered in itself, is reduced to a principle of mere passivity and receptivity. The realization of form in matter is the goal of natural activity, and although there are various combinations and separations of elements, it is always for the sake of a form; hence, the teleological view, as opposed to the mechanistic, remains dominant. But purpose is now found in the unconscious workings of form as well as in the conscious activities of rational soul. Although Aristotle conceived the natural universe as impregnated with and illuminated by form, for the ultimate explanation he too reached beyond nature. It is the desire to imitate the fully actual reality of Pure Form that, in the final analysis, explains all the ceaseless processes of nature.

Later Modifications. Both the Platonist and the Aristotelian view of nature extended into the Middle Ages. The early period was largely Neoplatonist, but in the 13th century the commentaries of St. albert the great and especially of St. thomas aquinas brought the Aristotelian doctrine of nature into the foreground.

In the 16th and 17th centuries, the rapid development of the new empirico-mathematical science was accompanied by an emphatic rejection of teleology: the conception of natures tending to ends. At first, change was Platonistically explained by an inherent, creative principle (natura naturans ) animating and directing the world of nature (natura naturata )—terms that go back to the Latin translation of averroËs. see world soul (anima mundi). Before long, however, under the influence of F. bacon, J. kepler, G. galilei, R. descartes, I. Newton, and others, the account became thoroughly mechanistic. With the rejection of the geocentric astronomy and the adoption of the universal law of gravitation, the qualitatively differentiated world of Aristotle gave place to a totally homogeneous universe. Purely qualitative differences, such as color, were considered to be functions of quantitative structure, and were soon dismissed as mere appearances to a sentient mind. Matter as potency was replaced by matter as mass and extension. All change was reduced to the motion of smallest parts in space; all causality, to prior events, i.e., to prior motions, identical causes being followed by identical effects. The spontaneous activity of bodies gave way to the idea of force (impact, attraction) and the impulse toward ends was displaced by inertia, the disposition to remain always the same. Nature thus became, for the scientist and the philosopher of nature alike, a mechanical system of inert, homogeneous mass-bodies, situated in space and time, moved by external forces, and utterly devoid of all but quantitative properties. (see mechanism.)

In the 20th century, the adequacy of purely mechanistic principles of explanation has been seriously questioned for the biological and psychological sciences. Further, the scientific theories of evolution along with the physicist's conception of matter as energy have made more generally acceptable a view that was already to some degree in evidence in the philosophies of G. W. leibniz and G. W. F. hegel, viz, the idea of nature as internally active and engaged in process. This conception, to which in some instances has been added the idea of aim, has found philosophical expression in the works of such thinkers as H. bergson, S. alexander, and A.N. whitehead.

Aristotelian Analysis. A fuller presentation of the Aristotelian concept of nature, which has been generally adopted by scholastic thinkers, entails considering his definition of nature, nature as passive, nature as active, end as nature, and related concepts.

Definition of Nature. Aristotle (Phys. 192b 8–32) reached his definition of nature by way of a comparison of the things that exist by nature (viz, animals and their parts, plants and simple bodies) with those that exist by other causes, in particular by art. The former are seen to have within them a tendency to move, i.e., to change. The artifact as such has no such tendency. It has an inclination to change only accidentally insofar as it is made of a natural substance. Nature, then, concluded Aristotle, is the principle or cause of being moved and being at rest in that in which it is primarily, by reason of itself and not accidentally.

"Being moved" implies passivity. Strictly speaking, the principle that constitutes a thing as a mover is a nature only when the mover by its activity is itself moved. Also, motion here includes any kind of corporeal change, accidental or substantial; it excludes, however, spiritual operations, such as intellection. "Rest" implies the attainment of the end to which the movement was directed. The phrase "by reason of itself and not accidentally" excludes such cases as the doctor who cures himself. The art of medicine is, in this case, intrinsic but accidental to the one who is being cured, considered as such.

Nature as Passive. Nature, thus defined, was identified by Aristotle first (Phys. 193a 10–30) with matter taken as the substratum of change, i.e., as the passive, potential principle of being moved. In opposition to the pre-Socratics, Aristotle conceived of the ultimate material principle (primary matter) as being of itself bereft of all form, purely passive, pure potentiality. The matter, however, from which becoming proceeds, taken in its concrete existence, is always determined matter. The substantial form currently possessed, determining the matter in a particular way, always limits and defines matter's immediate potentialities. This is true both for the potency of primary matter for new substantial forms and more obviously for the accidental receptivities characteristic of any given being. Furthermore, since the form already possessed by the matter can be the source of certain activities as well, the matter on which a natural agent operates, just as it is never pure potency, need not be entirely passive. Its activity, in fact, may run contrary to the aim of the agent.

Nature as Active. It is especially with form, however, that Aristotle is concerned to identify nature (Phys. 193a 30-b 19). The ancients, not distinguishing the two principles of matter and form, had conceived of their primordial stuff as already determined and capable of activity. Once substantial form is disassociated from matter and recognized as principle of essential determination, source of activity, and end of generation, it becomes obvious that form more than matter deserves to be called nature. Nature, then, as active principle of movement, is substantial form. (Note that, although one says "Nature acts," strictly speaking it is the composite substance that acts in virtue of its nature.)

Form is the source of two different types of activity in nature. First and more obviously, form is the intrinsic source of the vital activities of the living body. As such, it is known as soul. And as such it is a nature, since, by these activities, the living being is itself moved. The soul, in fact, is the primary source of activity whereby one part of the heterogeneous composite moves another part. Moreover, all the vital activities are either movements themselves (e.g., growth) or essentially connected with movements (e.g., sensation) or they pre-suppose movements (e.g., intellection). The soul, however, is also the principle of generation, an activity that is essentially directed to another substance. But even as such, it is a nature, insofar as the movement takes place within the same species, if not within the same individual (Meta. 1032a 15–26).

Second, form is the intrinsic source of the spontaneous activities characteristic of a given body, e.g., a chemical element (Gen. et cor. 323b 2–324b 25). Inanimate bodies, not having differentiated parts, do not move themselves. Their activities, on the contrary, are directed to other bodies that in turn may affect them. The forms, in this case, satisfy the requirement of interiority in the definition of nature insofar as they are parts within a system of interrelated active and passive potencies.

In Aristotle's cosmology, however, there are certain movements of bodies that do arise from an intrinsic source (Phys. 254b 33–255b 31), as in his example of a body falling to the ground—a movement that does not appear to require an external agent (see motion, first cause of). In this case, however, nature functions as a principle of activity without constituting the thing as a mover. The body, in fact, does not move itself, part moving part, as does the living thing. For Aristotle, rather, the movement arises spontaneously from the impulse of the form toward what is appropriate to it, which, in this instance, is a suitable environment. (For a study of this conception in conjunction with the theories of gravity and relativity, see J.A. Weisheipl.)

End as Nature. Whether a movement is natural or not cannot always be determined by sole reference to the active and passive principles. The determining factor is ultimately the end of becoming, and this too is nature (Phys. 193b 13–19, 194a 27–32).

Nature, in one sense, has been identified with the receptive and determinable principle. There are, however, in the world of nature, potencies that are not natural: the capacity of a natural body to take on an artificial form, or the capacity to be altered by some violent action. The natural potency differs from these in that it is a positive inclination to an act that perfects or fulfills the being so inclined, or else contributes to the good of the species or even to the good of the universe as a whole. The passive principle in nature, moreover, is normally related to a natural agent, through the activity of which it is brought to act. The activity of natural agents is accounted for by the tendency of the form in nature to actualize and bring to completion what is potential either within the same individual or beyond. The natural agent, then, actively tends to that good or perfection to which the potential principle is passively inclined. Furthermore, the natural agent, fixed in its species by its form, is also determined by this same principle with respect to specific goals, which it attains for the most part. Thus the acts to which it naturally directs matter by its activity are determinate acts. It is in this sense that a nature is said to act for an end. (Obviously, the end as a good is more easily recognized in the activity of living beings than it is in the workings of the inanimate world.) Consequently, it is the act or form, considered as the end to which a natural being tends either actively or passively, that determines whether a process is or is not in accordance with nature. And in those cases where the good of the whole is in opposition to the good of the individual (as in the case of corruption), it is the former that takes precedence as a determining principle. (see finality, principle of.)

The form considered as end, furthermore, is itself properly called nature. It is a principle of becoming, and one that, in the essential order of things, is prior even to the passive and active principles as such. It is also intrinsic, insofar as natural movements are for the sake of the form (finis cui ) from which they spring. In fact, the natural form seeks its own preservation and development within the individual; it tends by generation to its own continuance, as a specific form, in other individuals; and ultimately, by realizing its specific ends, it contributes to the order and preservation of the universe, i.e., to the good of the whole of which it is a part.

Related Concepts. Art, violence, and chance are all active principles that presuppose nature but operate outside the order of natural finality. see art (philosophy).

Secondary Meanings. From nature meaning the form or essence that is the end of generation, the word has been extended to signify any essence whatsoever without reference at all to becoming (see Thomas Aquinas, In 5 meta. 5.822–823). This sense, as applicable to any being, material or immaterial, is frequently conveyed by the terms definition and quiddity. A meaning somewhat closer to the original is that of essence as the source of any activity, whether of physical movement or of spiritual operation (De ente 1). This sense, too, is sometimes conveyed by the term substance. For a fuller discussion of these concepts, see essence; form; definition; quiddity; substance. For a treatment of laws of nature, see physical laws; natural law; and for the principle of the uniformity of nature on which such laws are based, see uniformity.

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[s. o'flynn brennan]