Nature

Aristotle takes nature to be an intrinsic principle rather than an aggregate of things. Whatever has a nature has within itself the source or cause of its being moved and of being at rest, and it has this primarily, not by derivation from something else. The contrast which gives the term its force is with art. A bed is made of wood by the contrivance of a craftsman, and its nature is the wood rather than the bed, since only the wood has a tendency of its own. On this view the natural is what a thing does of itself, and the artificial is what man has added to it. The issues raised by the opposition between the works of nature and the works of man are treated more fully under the idea of Art.

Because natural things move toward characteristic states, Aristotle holds that final causes operate throughout nature and not merely where a conscious agent deliberates. The seed tends toward the tree, the heavy body toward its place, and each kind toward the activity proper to it. Nature, in the maxim he repeats, does nothing in vain. This teleology is bound up with a claim about regularity, for the natural is that which happens either always or for the most part, in contrast with what happens by chance. Whether ends so conceived belong to things themselves or are supplied by the mind that observes them is a question on which later writers divide, Bacon assigning the investigation of final causes to metaphysics and Spinoza excluding them from nature altogether.

Aristotle also enumerates several senses of the term, of which the most general is nature as essence. To state the nature of anything is to say what it is, which is to define it, so that the study of natures cannot be separated from the problems of definition and classification. A further distinction, that between natural and violent motion, marks off what proceeds from a body's own principle from what is imparted to it by the motions of other bodies; Galileo and the physicists who follow him retain the distinction while altering its content. Since physics treats what is both sensible and mutable, things thought to be exempt from change fall to mathematics or to metaphysics rather than to natural science.

The Aristotelian conception governs natural philosophy in the West for many centuries, and Aquinas takes it up and sets it within a doctrine of creation. It is displaced, though not in every particular refuted, when Descartes and Galileo undertake to explain natural change by matter and motion alone. The questions it raises about purpose, about the reality of natural kinds, and about whether such kinds are fixed or variable, are pursued further under the ideas of Evolution and Definition.

Marcus Aurelius states the Stoic conception of nature as the whole of things. The universe is a single living order governed throughout by a rational principle, which the Stoics call the logos and identify with divinity inherent in nature rather than standing outside it. Nature in this usage is not restricted to bodies in motion or to the world of sensible change; it takes in gods and men, the course of events and the reason which governs them. Among the writers of the tradition only the Stoics and, much later, Spinoza employ the term in so comprehensive a way. Where others oppose the natural to the divine, or to the human, or to the artificial, Marcus Aurelius includes within nature whatever happens at all.

A rule of conduct follows from this conception. To live well is to live in accordance with nature, which means both in harmony with the order of the whole and in accordance with the rational nature belonging to man as a part of that whole. Nature thus supplies a standard of the right and the good, a use of the term which recurs in the natural law of the medieval writers and in later doctrines of natural rights. The Stoic does not resist events but consents to them, on the ground that what befalls him proceeds from the reason he shares. Whether such consent leaves room for deliberation and choice is a question the tradition returns to under the ideas of Fate and Will.

Marcus Aurelius dwells on the unity of nature and the connection of its parts. Nothing occurs in isolation, and man, being a portion of the whole, has a nature which is social as well as rational; the bee and the hive furnish him with an image of the relation between part and whole. The comparison is one that other writers press in the opposite direction, since Aristotle distinguishes the hive, which is formed everywhere in the same way, from the human city, whose forms vary with the arrangements men institute. How far human association is natural and how far conventional is considered under the ideas of the State and the Family.

The Stoic doctrine passes into Christian thought through the natural law, though Aquinas separates the providential order, which encompasses even what men suffer as evil, from the proper activity of each created nature. Spinoza revives the identification of nature with the divine whole while rejecting the final causes the Stoics retained. The difficulty which both inherit, whether an order in which everything happens as it must leaves any ground for moral striving, belongs to the discussions gathered under the ideas of Fate and Liberty.

Aquinas takes over the Aristotelian account of nature and sets it within a doctrine of creation. The most basic division on this view is between the uncreated and the created. God alone is uncreated; everything else has its being from God and is therefore a nature. Nature in this sense reaches beyond the world of bodies to the whole of the spiritual creation, so that angels and souls are no more supernatural than stones are. The word is used collectively for the entire world of creatures and distributively for each kind of thing which has its being from God, and the Aristotelian teleology is preserved within it, since the ends toward which creatures tend are the ends their Creator gave them.

How much efficacy belongs to created things is a further question. Some, Aquinas reports, have understood God to work in every agent in such a way that no created power has any effect, so that it is not fire which gives heat but God in the fire. He rejects this on two grounds. It would take the order of cause and effect away from created things, which implies a lack of power in the Creator; and it would leave the operative powers evidently present in things with no purpose to serve. God works in things in such a manner that things have also their proper operation. Natural causes are real causes, though they remain instrumental to the first cause which preserves them in being.

This leaves the natural distinguished from the supernatural in a second sense, that of what happens in the course of nature as against what happens through God's action outside the causes we know. A miracle, for Aquinas, is so called from the wonder that arises when an effect is manifest and its cause hidden, and he grades miracles by the degree to which the power of nature is surpassed, from the raising of the dead to the sudden curing of a fever. He does not suppose that a miracle accomplishes what is impossible or destroys the order it interrupts. On the side of human life the same relation holds between nature and grace, grace being said to perfect nature rather than to abolish it.

The autonomy Aquinas grants to secondary causes leaves natural philosophy free to proceed by its own principles, and the mechanical philosophers make use of that freedom while dispensing with the theology in which it was framed. Descartes allows God the creation of matter and motion and assigns everything afterward to the laws God laid down; Berkeley moves in the contrary direction and denies nature any productive power at all; Hume argues that uniform experience stands as proof against any miracle. Whether divine and natural causality can both be maintained is pursued further under the ideas of God and Cause.

Montaigne approaches nature by way of the variety he finds in it. Customs differ from country to country and from age to age; bodies alter so that a man is hardly the same from one decade to the next; the animals display capacities he is unwilling to rank below our own. What passes for a settled account of a rational and ordered nature seems to him to owe much to human self-regard, since nothing, as he remarks, is so firmly believed as what we least know. He does not deny that there is a nature. He doubts the reports men give of it, and he prefers the observation of particulars to the demonstration of systems.

The distinction which chiefly occupies him is that between nature and custom. Much of what men call natural is what they have grown used to, and the habits acquired in the course of a life come to operate with the force of an inborn tendency. Custom is on this account a second nature, a phrase which marks the whole question of what nurture adds to nature and which is examined further under the idea of Habit. Since peoples differ in what they find shameful, sacred, or reasonable, Montaigne concludes that the line between the natural and the conventional is drawn less securely than the moralists suppose, and that the appeal to nature in matters of law and morals often reports a local usage.

He extends the same doubt to the notion of the unnatural. What is called monstrous is often only unfamiliar, and nature in his view admits a wider range of forms than the standard of any one people allows. His comparisons of men with beasts work in the same direction, since he finds the distance between one man and another as great as the distance between a man and a brute. Whether human nature differs in kind or only in degree from the natures of other animals is a question taken up under the ideas of Man and Animal, and Montaigne's treatment of it leaves the boundary open where the classical writers had fixed it.

Montaigne's treatment of custom and variability enters the modern discussion at several points. Hobbes, who reduces nature to matter in motion, agrees that the institutions of civil life are contrivances rather than growths, though he draws from this a conclusion about sovereignty that Montaigne does not reach. Rousseau later reverses the valuation and asks whether man lost by exchanging the natural condition for the civilized one. The skeptical arguments themselves are pursued further under the ideas of Knowledge and Opinion.

Hobbes conceives nature as body in motion. There are no inner tendencies in things, no ends toward which they strive, and no qualities in bodies answering to the colors and sounds that appear in sensation. Whatever happens is to be explained by the motions of bodies acting upon one another, and the method proper to such explanation is the geometrical one of resolving effects into their causes and composing causes into their effects. Final causes are set aside, in the manner Bacon had recommended for physics, so that the maxims of the older natural philosophy lose the sense they carried for Aristotle, and the term nature comes to mean the whole of what moves and is moved.

Man is included in this order without exception. Sensation is motion in the organs of sense, imagination is decaying sense, and the passions are motions of approach and retreat named according to their objects. Deliberation, on this account, is the alternation of appetite and aversion, and the will is the last appetite before acting, so that Hobbes denies freedom of the will as it is commonly understood. He nonetheless keeps a place for the distinction between what men contrive and what happens without human contrivance, and it is on this distinction, rather than on any freedom exempt from natural causes, that his political philosophy turns.

The state of nature is the condition of men considered apart from any common power able to hold them in awe. Driven by competition, diffidence, and glory, and being nearly equal in strength and in hope of attaining their ends, they are in a war of every man against every man, and the life of man in that condition is solitary, poor, nasty, brutish, and short. Hobbes offers this less as an account of a period of history than as an account of what men are when the artificial restraints are removed. The commonwealth is accordingly an artificial body, made by covenant, and whether the state is natural or conventional is pursued further under the idea of the State.

Hobbes's reduction of nature to matter in motion, and his treatment of civil society as a work of human art, set the terms in which the later writers argue. Locke accepts much of the physics while denying that the state of nature is a state of war, and he adds a natural society governed by reason which Hobbes does not admit. Rousseau reverses the account of the natural condition, and Hegel treats the antithesis of nature and spirit in a way that leaves no room for it. Whether human action constitutes an exception to the reign of natural necessity remains at issue under the ideas of Will and Liberty.

Descartes identifies the nature of body with extension. A body has length, breadth, and depth, and its modifications are shape, size, position, and motion; the colors, sounds, tastes, and odors that appear in sensation are referred to the mind rather than to the things themselves. Whatever occurs in the physical world is therefore to be explained by the arrangement and motion of extended parts, and the science of nature becomes continuous with geometry. The substantial forms and real qualities which the schoolmen assigned to bodies are dispensed with, as are the ends that Aristotle found operative in every part of nature.

Descartes does not on that account remove God from the account of nature. God creates matter, forms it into bodies, and imparts to them their initial impetus; thereafter the laws which God laid down for them to follow are sufficient, and natural causes operating under those laws explain the course of events without further intervention. This position stands between two others. Berkeley allows nature no productive power whatever and makes God the immediate cause of every sensible effect, while Lucretius denies both the creation of the world and the intervention of the gods in its processes. What guarantees the constancy of the laws, for Descartes, is the constancy of God.

Nature so defined does not include thinking substance. Mind is unextended and its acts are not motions, though minds are as much finite creatures of God as bodies are. The distinction preserves the freedom and the immortality of the soul from a mechanics which otherwise admits no exception, and it also permits Descartes to treat animals, which he takes to be without thought, as machines. What remains obscure is the manner in which two substances so defined act upon one another, a difficulty examined under the ideas of Mind and Soul. Spinoza afterward removes the difficulty by making thought and extension attributes of one substance.

The mathematical treatment of nature which Descartes proposes is carried further by the physics that follows him, whether or not his particular explanations are retained. The separation of nature from mind proves less durable, and Kant reconstitutes it as a division between the phenomenal order and the order of freedom rather than between two substances. The exclusion of final causes from the study of bodies is treated further under the idea of Cause, and the question of the animal soul under the idea of Animal.

Locke distinguishes the state of nature from civil society without supposing that the first is a condition of war. Men in it are free to order their actions and dispose of their possessions and persons within the bounds of the law of nature, and that law, which reason teaches to all who will consult it, obliges each not to harm another in his life, health, liberty, or possessions. Locke differs here from Hobbes, and from Kant and Hegel after him, all of whom take the state of nature to be a state of war. He goes further and allows that men living together according to reason, without a common superior on earth, already constitute a society, so that natural society is distinguished from political society rather than opposed to it.

What the state of nature wants is not law but a judge. Each man in it has the right to execute the law of nature, to defend himself and to punish transgressors and seek reparation, and it is the partiality of men in their own cases which turns disagreement into violence. Civil society is instituted to supply the common authority that is missing, and natural freedom is not surrendered so much as secured. On this account the institutions of political life are of man's own devising, which is why states differ from one another in their forms while the bee-hive is everywhere the same. The naturalness of the state and the ground of political obligation are considered further under the ideas of the State and Government.

Locke's use of the term is not confined to political matters. In his account of the understanding, simple ideas are given to the mind, which can neither make nor destroy them, while complex ideas are framed by the mind's own composition, and the division runs parallel to the older distinction between nature and art. He holds further that the essences by which we sort things into kinds are nominal rather than real, being made by the understanding for its own convenience. Whether our definitions signify the natures of things as they are is a question pursued under the ideas of Definition and Idea.

Locke's doctrine of a law of nature antecedent to civil institutions passes into the political writing of the eighteenth century and into the founding documents of the American republic. Hume, taking up the same subject, denies that either the law of nature or the obligation of contracts can be established in Locke's way, and derives both from utility and custom instead. Rousseau retains the state of nature while giving it a different content, and the several senses in which rights are called natural are examined under the ideas of Justice and Liberty.

Hume examines what is meant by the uniformity of nature and finds that the necessity men attribute to it is not given in what they observe. We see one event follow another and, after many such observations, come to expect the second on the appearance of the first; but no impression answers to the connection we suppose to bind them. All inferences from experience are therefore effects of custom, not of reasoning. The laws of nature record what has been found constant, and the expectation they support is a habit of the mind rather than a demonstrated truth about things.

This does not lead Hume to treat nature as a fiction. Nature has determined us to judge as it has determined us to breathe and feel, and belief in the course of things is not within our power to withhold. He speaks of a kind of pre-established harmony between the course of nature and the succession of our ideas, by which our expectations answer to what happens without our understanding why they should. Nature in his usage tends to mean the reality which lies behind appearances and which we assert when we affirm matters of fact, as distinguished from the relations among our own ideas. Where Spinoza had counted the system of ideas as much a part of nature as the system of bodies, Hume keeps the two apart.

The account bears on what may be admitted as an event in nature. A miracle, Hume argues, is a violation of the laws of nature, and since a firm and unalterable experience has established those laws, the proof against a miracle from the nature of the fact is as entire as any argument from experience can be. He applies the same naturalism to man, treating morals, politics, and the operations of the understanding as effects of the passions and habits which make up human nature, so that the science of man becomes the foundation of the other sciences. The comparison of his position with that of Aquinas, who holds that divine action within the order of nature need not violate it, is drawn under the idea of Religion.

Hume's analysis of causal necessity is the occasion of Kant's critical philosophy, which grants that no such necessity is found among the impressions of sense and locates it instead in the conditions of experience. His account of human nature as an object of empirical inquiry is taken up by the moral and psychological sciences of the following century. The problem of induction which he raises is discussed further under the ideas of Cause and Experience.

Kant answers Hume by granting that necessary connection is not to be found among the impressions of sense, and by locating it instead in the conditions under which experience is possible at all. The categories of the understanding, substance and causality among them, are not derived from nature but prescribed to it, since without them the manifold of sense could not be thought as one connected world. Nature, in the sense in which the theoretic sciences investigate it, is the existence of things so far as it is determined according to universal laws, and those laws hold necessarily because they state the form of any possible experience.

Kant distinguishes two expressions which are commonly interchanged. World denotes the mathematical total of all phenomena and the totality of their synthesis; the world is termed nature when it is regarded as a dynamical whole, when attention is directed not to the aggregation of phenomena in space and time but to the unity of their existence. Nature so understood is coextensive with possible experience and with the realm of time, space, and causality. What lies outside the range of sense, which Kant calls the supersensible or the noumenal, is no object of natural science, and the older attempts to reach it by theoretical argument are set aside.

The order of nature is accordingly separated from the order of freedom, and the separation is as radical as the Cartesian division of matter from mind, though the line is drawn elsewhere. Everything that appears is determined by causal law, while the moral life of man belongs to an order unconditioned by time, space, and causality, and falls to the practical rather than the theoretic sciences. In the Critique of Judgment Kant considers a third way of regarding nature. Living things present themselves as organized and self-maintaining, and we cannot help judging them as if they were purposive, though such purposiveness is a maxim of reflective judgment and not a law of nature itself.

Kant leaves the natural sciences in possession of their necessity while denying that they reach things as they are in themselves, and both halves of the result are contested. Hegel rejects the confinement of knowledge to appearances and undertakes to exhibit nature as a stage in the development of the Idea. The teleology which Kant admits only as a principle of judgment is claimed by others as a principle of nature. The antithesis of the phenomenal and the noumenal, and with it the antithesis of nature and spirit, is considered further under the ideas of Liberty and Metaphysics.

Hegel places nature within a system in which the Idea, the rational principle of what is, passes through three stages. Logic treats the Idea in itself; nature is the Idea in the form of otherness, external to itself; spirit is the Idea returned to itself in self-conscious freedom. Nature on this account is neither an inert given nor a mere mechanism, but reason in a condition of externality, and the task of the philosophy of nature is to recognize in that externality the same rational structure which logic exhibits in its own terms. The antithesis of nature and spirit, rather than the antithesis of nature and art or of nature and convention, is the one that organizes his treatment.

Hegel accepts the results of the physical sciences while denying that mechanical explanation exhausts the intelligibility of nature. He orders the subject matter in ascending stages, from the mechanical through the physical to the organic, each of which takes up what precedes it and transforms it. Life is the stage at which a natural thing maintains itself in relation to itself, and so anticipates the self-relation that becomes explicit in spirit. Questions about continuity and hierarchy in the order of nature, and about whether the higher kinds can be reduced to the lower, are pursued further under the ideas of Evolution and Life and Death.

Against Kant, Hegel denies that nature is only the sum of appearances ordered by our categories; against Descartes, he denies that mind stands outside the natural world as a second substance. Nature is the other of spirit, but it is spirit's own other, and the opposition is one the system undertakes to overcome rather than to preserve. Hegel nonetheless allows that nature displays a contingency and a want of order for which the concept cannot altogether account. The forms of nature do not realize their notion as exactly as the categories of logic do, and the philosophy of nature has to acknowledge this impotence rather than explain it away.

Hegel's is the most sustained philosophy of nature attempted since Aristotle, and it restores a teleological treatment of natural things without setting aside the sciences that had displaced it. Its influence runs in opposite directions, to the dialectical materialism of Marx and Engels, which keeps the method while reversing the priority of nature and spirit, and to the idealisms which keep the priority and abandon the method. The antithesis it seeks to resolve remains a standing question in the discussions gathered under the ideas of Mind and Man.