Metaphysics

Plato nowhere uses the word "metaphysics," and the discipline which later ages designate by that name he calls dialectic. It is the name he gives to the search for first principles and for the knowledge of the most intelligible realities. The world disclosed by the senses is, on his account, a realm of becoming, in which nothing remains for long what it is; the Forms constitute the realm of being, stable, intelligible, and always the same. The philosopher ascends from sensible particulars to the intelligible universals which explain them, and in the Republic that ascent terminates in the Form of the Good, which stands to the intelligible order as the sun stands to the visible, being at once the cause of the being of things and of our knowledge of them. Dialectic is placed above the mathematical sciences, which build upon hypotheses they neither establish nor examine, whereas dialectic treats hypotheses only as steps toward a principle that rests on none. Their relation is considered more fully under the ideas of Dialectic and Mathematics.

In the Sophist the inquiry takes another turn. To distinguish the sophist from the philosopher, Plato is led to ask what can be meant by saying that a statement is false, and so to the problem of non-being. His analysis of the greatest kinds, among them being, sameness and difference, rest and motion, concludes that these blend with one another in a communion which makes discourse possible, so that what is not may in some manner be said to be. The same terms reappear as the fundamental concepts of the first philosophy in Aristotle and, in the medieval schools, as the transcendental terms. Dialectic is also, in the Republic, the last stage in the education of the guardians, so that the highest science bears directly upon the government of the state. The doctrine of participation, by which particulars share in the Forms and the Forms in one another, raises questions pursued under the ideas of Being, One and Many, and Same and Other.

Plato sets the ambition which the tradition after him inherits: a science of what truly is, distinct from and superior to the study of appearances. Aristotle retains the ambition while denying that the Forms exist apart from the things which bear them, and Plotinus carries the ascent beyond being itself to the One. Whether the highest science is best conceived as dialectic, as first philosophy, or as natural theology is a question on which the later tradition reaches no agreement, and it is discussed further under the ideas of Dialectic, Philosophy, and Wisdom.

Aristotle nowhere uses the word by which his treatise is known; the title appears to derive from the Alexandrian librarians, who placed the work after the books on physics. He speaks of the discipline as wisdom, as first philosophy, and as theology. Its subject is being as being: not this or that kind of being, which the special sciences mark off as their several genera, but whatever is, in so far as it is, together with the attributes belonging to it in virtue of its own nature. Physics considers things as they share in movement, and mathematics considers them as quantitative and continuous; neither asks whether the genus it treats exists at all, since it belongs to the same kind of thinking to show what a thing is and that it is. To the first philosophy belong also the axioms which hold for all things whatsoever, chief among them the principle that the same attribute cannot at once belong and not belong to the same subject in the same respect. The standing of that principle is examined under the ideas of Principle and Opposition.

The central books, however, are occupied with sensible substances: with the distinction of substance and accident, form and matter, potentiality and actuality, and with such properties of things as their unity and divisibility, their sameness and otherness. Aristotle does not inquire whether these substances exist, calling them the readily recognized substances; he asks how they exist. The concluding books raise a further question, whether there is any substance capable of separate existence apart from sensible things, and it is here that the science is also called theology, since if the divine is present anywhere it is present in what is eternal, immovable, and immaterial. Whether the first philosophy is therefore a general science of being which culminates in theology, or is theology throughout, is a question on which his commentators divide. Aristotle himself appears to hold that knowledge of the highest being illuminates being universally, because the first cause of motion is a principle of all that is.

Both conceptions of the first philosophy, as a science of being in general and as a science of the highest being, run through the whole tradition Aristotle founds. Aquinas takes them to be reconcilable, God being that being whose essence is to exist and by which all other beings are; Bacon separates natural theology from metaphysics proper and assigns to metaphysics the formal and final causes; Kant, denying that reason can reach any object beyond the conditions of experience, withholds the name of valid science from natural theology altogether. The questions belonging to each conception are pursued under the ideas of Being, Cause, Form, Matter, and God.

Plotinus carries the Platonic ascent further than Plato takes it. For Aristotle, being is the ultimate subject of the first philosophy; for Plotinus there is a principle beyond being, the One, which is not a being among beings but the source from which all being proceeds. Intellect, the second hypostasis, arises when the overflow of the One turns back upon itself in contemplation, and Soul arises in turn from the overflow of Intellect, the material world standing lowest as the last of these emanations. The One is accordingly not to be numbered among the things it produces, and no predicate drawn from them applies to it properly. Whether such a principle can be an object of science at all, or whether the highest discipline must end by acknowledging that its object exceeds every concept and proposition, is the difficulty this doctrine presses upon those who follow him. The hierarchy of the hypostases and the doctrine of emanation are considered further under the ideas of Being, One and Many, and God.

Plotinus keeps the name dialectic for the highest study, and defines it as the discipline which brings with it the power of pronouncing with final truth upon the nature and relation of things: what each is, how it differs from others, what quality all have in common, and whether the being of each is real being. But dialectic, he insists, is not to be thought of as the mere tool of the metaphysician. It goes beyond metaphysics as vision goes beyond discursive reasoning, leaving to another science the coil of premises and conclusions which is the art of reasoning. The ultimate principle is reached, if it is reached, not by demonstration but by a union in which the distinction of knower and known disappears. The question whether there is a form of knowledge higher than metaphysical science is thus raised, and the Christian theologians take it up in their own way, treating such knowledge under the ideas of Wisdom and Theology.

The placing of the One beyond being leaves two routes open, and later writers take one or the other. God may be conceived as the fullness of being, which is the way of Aquinas following Aristotle, or as transcending being so far that no predicate holds of him, which is the way of the negative theology that draws upon Plotinus. Augustine and Aquinas borrow much from him while declining his account of the ascent, holding that the vision he describes exceeds natural wisdom and comes as a gift beyond the reach of unaided reason. What bearing this has on the limits of the highest science is discussed under the ideas of Knowledge, God, and Truth.

Aquinas takes over the Aristotelian conception of the first philosophy and sets it in relation to a science whose principles are articles of faith. Metaphysics studies being as being by the natural light of reason; sacred doctrine studies God as he has revealed himself. He must therefore meet the objection that no knowledge beyond metaphysics is needed, since everything that is, God himself included, is treated in that part of philosophy which Aristotle called the divine science. His answer is that certain truths necessary for the salvation of man exceed the reach of reason, and that even those truths about God which reason might discover would be known only by a few, after a long time, and with an admixture of many errors. The two sciences differ in their principles and in some measure in their methods, yet they do not contradict one another, since truth cannot be contrary to truth. Their relation is treated more fully under the ideas of Theology, God, and Religion.

Within metaphysics itself, Aquinas develops the distinction between essence, or what a thing is, and existence, or that it is. In every created thing the two are really distinct, for the nature of a horse does not include the actual existing of any horse; in God alone are they identical, his essence being to exist. On this distinction rests the account of creatures as contingent and of God as necessary, and with it the demonstrations which proceed from the things of sense to a first cause. The doctrine gives the first philosophy a determinate content: the most general characters of whatever is, considered in the light of the composition of essence and existence, and pointing toward a theology which reason can begin but not complete. The questions here opened are pursued under the ideas of Being, Cause, and Necessity and Contingency.

That every created being might not have existed, while God exists necessarily, becomes a fixed point of reference for later discussion, whether in agreement or in dissent. Descartes undertakes to prove the existence of God from the idea of a perfect being, without recourse to the composition of essence and existence in creatures; Locke doubts that we possess any clear idea of substance from which such demonstrations might proceed; and Kant argues that existence is no predicate at all, which if granted would close both routes. Whether natural theology is the whole of metaphysics or only its crowning part remains in dispute, and is examined further under the ideas of God and Theology.

Descartes proposes a new beginning for the first philosophy. Where the schools had founded metaphysics upon being, he founds it upon certainty. The Meditations submit to doubt the testimony of the senses, the truths of mathematics, and the existence of bodies, and what survives the doubt is the thinking self. From that principle he undertakes to demonstrate the existence of God, arguing that the idea of a perfect being could not have arisen in a mind which is imperfect, and by the veracity of God he recovers the world which doubt had suspended. He describes the work, in the letter prefixed to it, as concerned with God and the human soul, holding that these two questions ought to be settled by philosophical rather than theological argument. The whole of metaphysics is thus given a theological character while its method remains that of natural reason. What bearing this has on sacred doctrine is considered under the ideas of Theology and God.

The reality which the new principles disclose is divided into two kinds of substance, the thinking and the extended, and it is by the immateriality of the one and the materiality of the other that Descartes separates metaphysics from physics. He compares philosophy to a tree whose roots are metaphysics, whose trunk is physics, and whose branches are the other sciences, so that the first philosophy is not a discipline standing apart but the foundation on which the rest are to be raised. Whether two substances so unlike can act upon one another, what substance is, and how the mind can know bodies at all, are questions which arise from this starting point and occupy his successors. Descartes has not abandoned metaphysics; he has proposed to rebuild it, and whether the foundation will bear what is placed upon it is the question his readers press. These matters are pursued under the ideas of Mind, Matter, and Soul.

With Descartes the order of inquiry is reversed, for what is first in being is no longer first in knowledge, and the examination of the knowing subject precedes the account of what is. Spinoza accepts the definition of substance and concludes that there can be but one; Locke doubts that we have any adequate idea of substance whatever; Kant asks what the first philosophy may still claim once the powers of reason have themselves been examined. Whether an analysis of mind is prior to metaphysics, or already presupposes one, is a question the later examinations of the understanding leave unsettled, and it is discussed under the ideas of Knowledge, Mind, and Philosophy.

Spinoza does not use the word metaphysics, yet he holds that the human mind possesses an adequate knowledge of the eternal and infinite essence of God, and the Ethics opens with an account of what there is. A substance, by his definition, is that which is in itself and is conceived through itself. Descartes had admitted two created substances, the thinking and the extended, alongside the uncreated substance which is God. Spinoza argues that there can be only one, since a substance possessing infinite attributes could be limited by nothing outside itself, and nothing would remain outside it from which a second might be constituted. This one substance he calls God, or Nature. Thought and extension, which Descartes had made two substances, become two of the infinite attributes under which the one substance is conceived; particular minds and bodies are then not substances but modes, that is, modifications of substance under one attribute or another. The conception of substance is examined further under the ideas of Being and God.

The Ethics proceeds in the geometrical order, from definitions and axioms through propositions and demonstrations, on the view that things follow from the nature of God with the same necessity by which the properties of a triangle follow from its definition. Contingency is accordingly denied. Chance is a name for our ignorance of causes, and freedom of the will an imagining which arises because men are conscious of their appetites and not of the causes by which those appetites are determined. The title of the work indicates that this account of what is has a practical end. Knowledge of the one substance is offered as the means by which the mind is freed from bondage to the passions and brought to that intellectual love of God in which blessedness consists. How a doctrine of universal necessity bears upon conduct is discussed under the ideas of Necessity and Contingency, Will, and Happiness.

Few positions in the tradition have been so variously received. Leibniz, unwilling to admit a single substance, multiplies substances into monads; Hegel treats the one substance as a beginning which must be developed into subject; the writers of the Romantic period find in it a doctrine of nature; and Kant cites such reasoning as an instance of reason overreaching itself when it argues from concepts to existence. Whether reality is one or many, and whether the necessity Spinoza ascribes to all things can be reconciled with moral responsibility, are questions carried forward under the ideas of One and Many, Liberty, and Fate.

Locke uses the word metaphysics as a term of reproach, and the purpose of his Essay is to determine how far the understanding reaches and where it must stop. Our idea of substance, he argues, is obscure. We observe qualities which are found together, color, weight, hardness, and we suppose some support in which they inhere, but of that support we have no positive idea; it is a something, we know not what. The same holds of the mind. We have ideas of thinking, willing, and perceiving, and we suppose a substance in which these operations reside, though the substance itself escapes us. His conclusion is not that substances fail to exist, but that our ideas of them are inadequate to the demonstrations which have been built upon them. Knowledge, on his account, extends no further than the perception of the agreement or disagreement of ideas, and many of the questions in dispute concern things of which we have no clear ideas at all.

It does not follow that inquiry into immaterial things is idle. Locke observes that we discover in ourselves knowledge and the power of voluntary motion as certainly as we discover in things without us the cohesion and separation of solid parts, and that we have therefore as much reason to be satisfied with our notion of immaterial spirit as with our notion of body. He assigns greater certainty to our knowledge of God and of the soul than to our knowledge of bodies, and finds no greater difficulty in speculations about spirits than about the particles of matter. What he objects to is the raising of systems upon ideas which have never been examined, and the disputes about words which follow from it. His recommendation is one of measure: to mark out what can be known and to acknowledge what lies beyond. These matters are treated further under the ideas of Knowledge, Mind, and Soul.

The examination of our ideas, undertaken before any inquiry into things, becomes the characteristic modern procedure. Hume carries it further, denying validity to speculation concerning causes and substances even in the natural order, and Kant makes a critique of reason the condition of any metaphysics that is to come. Whether such an examination can be conducted without presupposing a metaphysics of its own is the objection urged against the whole undertaking, for psychology and epistemology may conceal metaphysical assumptions of their own. The scope and limits of the understanding are considered under the ideas of Knowledge, Experience, and Opinion.

Kant does not withhold the name of science from metaphysics on account of its method, for he holds that metaphysics, according to its proper aim, consists merely of synthetic propositions a priori, and it is by such propositions that mathematics and pure natural science are sciences at all. The difficulty lies rather with its objects. Metaphysics as he finds it in the schools has for the proper object of its inquiries three grand ideas, God, freedom, and immortality; and when reason has recourse to principles which transcend the region of experience it falls, he says, into confusion and contradictions, the arena of these endless contests being called metaphysic. The Transcendental Dialectic sets out the several forms which the failure takes: the paralogisms into which rational psychology falls, the antinomies which cosmology cannot escape, and the defects of the proofs offered for the existence of God. What is exposed is not the error of particular philosophers but an illusion natural to reason itself.

His aim, however, is a reformation of metaphysical inquiry rather than its abolition. We can know a priori that appearances stand in space and time, that substance persists through change, and that every event has its cause, since these are the conditions under which experience is possible; what we cannot know is how things stand apart from the forms of our sensibility and understanding. Metaphysics redefined as any system of knowledge a priori consisting of pure conceptions remains possible, and Kant proposes it in two parts, a metaphysic of nature and a metaphysic of morals. God, freedom, and immortality are then affirmed in the order of practical rather than speculative reason, as conditions of the necessary object of the will, though he adds that we cannot claim to know even their possibility. The distinction between the two uses of reason is treated under the ideas of Knowledge, Will, and Duty.

The critical philosophy divides the tradition it addresses. Hegel holds that the limits Kant assigns to thought are drawn from an inspection of the categories apart from their content, and undertakes to restore a knowledge of the absolute; the positivists extend the restriction and set metaphysics aside altogether; others observe that a critique of reason must itself proceed on principles which are not derived from experience. Whether metaphysics is a valid science, an illusion natural to reason, or a discipline still awaiting its proper method is the question left standing, and it bears on the discussions gathered under the ideas of Philosophy, Science, and Theology.

Hegel declines the restriction of metaphysics to the conditions of possible experience. Thought and being are not divided by a boundary which thought cannot cross; the categories of logic are not forms which the mind imposes upon a material otherwise unknown to it, but the determinations of what is. The Science of Logic is on this account at once a logic and a metaphysics. It begins with the emptiest of the categories, Being, which is shown to pass over into Nothing and with it into Becoming, and it proceeds through the determinations of quality and quantity to essence and at last to the Concept, in which the earlier categories are comprehended. Each category, taken by itself, is shown to be inadequate and to pass into its opposite, and the opposition is then resolved at a further stage. Whether logic and ontology can be identified in this manner is among the questions raised under the ideas of Logic, Being, and Idea.

Kant's error, on this view, was to examine the instrument of knowledge before employing it, as though the categories could be inspected apart from the content they articulate and then pronounced incapable of reaching things as they are. The categories are for Hegel the self-articulation of the Absolute, and what appears as a limit of thought is a stage in its development. The system accordingly does not end with logic. It passes into the philosophy of nature and the philosophy of spirit, so that art, religion, the state, and the course of history are treated as further determinations of the same whole rather than as subjects belonging to some other inquiry. The relation between the movement of thought and the movement of history is considered under the ideas of History, Progress, and Dialectic.

Hegel's is the last of the great systematic constructions in the tradition of the great books, and the reaction against it takes several directions. The positivists dismiss the undertaking entire; others retain the dialectical method while rejecting the idealism, as Marx does in turning it toward the material conditions of society; still others hold with Kierkegaard that existence cannot be contained within a system at all. Whether the highest science can comprehend its subject whole, or must confess a remainder which thought does not reduce, is the question his successors inherit, and it is pursued under the ideas of Philosophy, Wisdom, and Truth.