Being

Plato addresses the question of being in the context of the Eleatic problem inherited from Parmenides: being cannot come from non-being, and what truly is must be eternal and unchanging. But the world of experience is full of change, coming-to-be, and perishing. Plato's response is to distinguish two levels of reality: the realm of Forms, which truly are, and the sensible world, which merely becomes.

Being belongs properly to the Forms, such as Justice Itself, Beauty Itself, and the Good. They are intelligible, eternal, and self-identical; they are what sensible things imitate or participate in. The sensible world exists in a lesser degree: it is real enough to be studied, but its reality is derivative, mixed with non-being, and always in flux.

The Sophist refines this account. Plato concedes there that non-being, understood as difference, must itself be; otherwise we could not speak of what is not. Being is thus interwoven with sameness, difference, motion, and rest. This represents an advance on Parmenides, who had denied any status to non-being, and it is among the earliest structural analyses of the concept of being.

Plato's distinction between what truly is and what merely becomes was taken up and disputed by Aristotle, who argued that if the Forms are what truly is, and individual living things are only imperfect copies, the primary objects of natural inquiry are assigned a secondary metaphysical status. The question of whether being is properly ascribed to the intelligible, the sensible, or both pervades the subsequent tradition.

Aristotle opens the Metaphysics with the declaration that "being is said in many ways," and the whole science of first philosophy turns on this observation. There is not a single meaning of "is": something may be a substance, or a quality, or a quantity, or a relation, or an activity. All the other senses of being depend, however, on the first, which is substance.

Substance (ousia) is therefore primary being: the individual thing that exists in its own right, to which everything else is attributed. This horse, this human, this tree. The universal does not exist apart from the particulars that instantiate it. Form and matter are co-principles of each substance; together with potency and act, they explain what a thing is and how it changes.

Book XII of the Metaphysics ascends to the unmoved mover, pure actuality, the being whose activity is thought thinking itself. This is being in its fullest sense: necessary, eternal, without potentiality. The science of being thus extends from ordinary substances up to what Aristotle treats as theology, both falling under a single inquiry into being as such. Whether primary being is the individual substance of ordinary experience or the pure actuality of the unmoved mover is a question the Metaphysics leaves open, as discussed more fully under the idea of God.

Aristotle's formulation that being is said in many ways, all of which refer back to substance, distinguishes his account from Plato's, on which being is univocally ascribed to the Forms. Aquinas will adopt Aristotle's substance metaphysics but develop it further by explicitly distinguishing essence from existence, a distinction Aristotle is generally held not to have drawn in the same way.

Lucretius transmits the Epicurean answer to the Eleatic challenge. Parmenides had argued that being cannot come from non-being, and therefore nothing genuinely comes into being or passes away. Lucretius accepts this conclusion but applies it differently: it is the atoms that never come into being or cease to exist, and they alone satisfy the Eleatic demand for a being that neither arises nor perishes. What we call things, from mountains to human souls, are temporary arrangements of atoms in the void. Their arising and dissolution do not violate the permanence of being, since "the first-beginnings," as Lucretius calls them, persist through every change.

The nature of an atom is precisely to be: it is solid, indivisible, and free from the internal vacuity that makes compound things capable of dissolution. Atoms have shape, size, and weight, but no secondary qualities such as color, heat, or sound; these emerge only from their combinations. The void, correlatively, is pure non-being, furnishing the space through which atoms move. Reality at its foundation divides into two: that which is (atoms) and the space in which it moves (void). Everything else, every quality we perceive and every substance we name, is a mode of their interaction.

This account reframes the Aristotelian analysis of substance. For Aristotle, individual substances such as men and horses have genuine being, with their own forms and purposes, while matter is a kind of potentiality. For Lucretius, the only genuine beings are the atoms; compound things, including organisms and souls, are real but derivative, and their dissolution is not the perishing of being but only the rearrangement of it. The relation between atomist and Aristotelian accounts of substance bears on later discussions of Matter and Form.

Lucretius's identification of ultimate being with the simple, indivisible, and unchanging atom was available to the mechanical philosophers of the seventeenth century as they sought to replace Aristotelian substance with a physics of particles in motion. Descartes, though he rejected the classical void and defined matter as pure extension, shares with Lucretius the ambition to reduce the variety of sensible things to a small number of ultimate units whose being is stable and mathematically tractable.

Plotinus develops the Platonic account of being by arguing that Being itself is not ultimate. Even the Forms presuppose multiplicity, since they are many, and whatever is many presupposes something prior that is simply one. Beyond Being, therefore, is the One: utterly simple, ineffable, the source from which all that is proceeds.

From the One proceeds Intellect (Nous), the realm of Being and the Forms; from Intellect, Soul; from Soul, the sensible cosmos. This is emanation: reality flows from the One in descending levels of unity, each less one and more many than the last. Nothing is lost in the source; everything that comes forth remains, in some fashion, within it.

The soul's ascent is the reverse of this descent. By purification and contemplation, the soul ascends back through Soul and Intellect, and finally to a union with the One that Plotinus describes as beyond thought and language. Since the One, being absolutely simple, admits of no predicates, it cannot be reached by the discourse of reason but only by a mode of apprehension that surpasses ordinary cognition. The relation between this account of the One beyond being and the Aristotelian account of the unmoved mover as supreme being is discussed further under the idea of God.

Plotinus's account places Being as subordinate to the One, which is beyond being. Augustine will take over the general structure but alter its summit: the One that is beyond being and indifferent to persons cannot, on the Christian account, be the God who addresses Moses, and some accommodation between absolute simplicity and personal existence is required.

Augustine's account of being draws on two sources that he brings together: the Neoplatonist tradition, in which an immutable, intelligible reality stands above the mutable sensible world, and the Hebrew scriptures, in which God reveals his name to Moses as "I AM WHO AM." For Augustine, this divine name expresses the most fundamental truth about God: that God is not a being among beings but Being itself, and that creatures exist only by participation in him.

All created things both are and are not, on this account. They are, because they receive being from God. They are not, in the full sense, because they are mutable, finite, and subject to passing away. Evil is accordingly understood as a privation: not a thing with its own being, but a lack of the good being proper to a nature. The soul, when it turns away from God, loses being in proportion; when it returns to God, it is restored to itself. The implications of this account for the problem of evil are treated more fully under the ideas of Good and Evil and Sin.

Creation is for Augustine not a reordering of pre-existing matter but an act from nothing, ex nihilo, so that every creature owes its very existence, moment by moment, to God who is. The contrast between the being God has and the being creatures have is not merely a difference of degree but of kind: God's being is necessary and self-subsistent, while the being of creatures is wholly received and contingent.

Aquinas will take up the Augustinian identification of God as Being itself and develop it in strictly metaphysical terms, distinguishing essence from existence and holding that in God alone these are identical, whereas in every creature existence is received and therefore distinct from essence.

Aquinas builds on both Aristotle's substance metaphysics and Augustine's reading of the divine name in Exodus to draw a distinction he regards as fundamental: the distinction between essence, or what a thing is, and esse, its act of existing. In every creature these are really distinct: the essence of a phoenix can be conceived whether or not any phoenix exists. Existence is not included in essence; it is received.

Only in God are essence and existence identical. God is ipsum esse subsistens: subsistent Being itself, whose essence is simply to be. Every other being has existence; God is existence. This is Aquinas's interpretation of the Exodus name, given metaphysical precision. Creation, accordingly, is the communication of existence to essences that, considered in themselves, are nothing.

This doctrine has several consequences that Aquinas draws out. It explains the analogical use of "being" for both God and creatures: they are called beings not univocally, as if being meant the same in both cases, but analogically, with reference to a common source. It grounds the contingency of creatures: every creature could not-be, since its existence is not its essence. And it places God, as pure act of being, outside the hierarchy of beings that have existence only derivatively.

The distinction between essence and existence that Aquinas regards as central to any adequate account of being was not drawn in the same way by Aristotle, and its reception in the history of scholastic philosophy has been uneven. Descartes, by beginning with the certainty of the thinking self rather than with being as such, redirects the question of metaphysics in a way that leaves the esse-essence distinction without a secure place in subsequent modern philosophy.

Descartes's approach to the question of being begins with systematic doubt. He finds that one thing cannot be doubted: that he, the doubter, exists. Cogito, ergo sum: I think, therefore I am. This serves as the first certainty, and the starting point from which an account of being can be rebuilt. Being, on this approach, is first established from within the subjective experience of thinking, rather than by analysis of the external world or by reception of tradition.

From this foundation, Descartes proceeds to argue that the idea of a perfect being present in his mind could only have been caused by a perfect being; therefore God exists, and is not a deceiver. Grounded in divine veracity, he then recovers the external world, distinguishing two kinds of created substance: thinking substance (res cogitans) and extended substance (res extensa). Mind and body are, on his account, really distinct, each constituted by its essential attribute.

This dualism significantly alters the question of being. Substance is defined in terms of independence: it is whatever needs nothing else in order to exist, except God. The question of how two substances defined by entirely different essential attributes can interact becomes, on this account, difficult to resolve. The mind-body problem, in the form familiar from modern philosophy, arises from this definition of substance, and is discussed further under the ideas of Mind and Soul.

Descartes's procedure of establishing being through the self-certainty of the thinking subject shifts the orientation of metaphysics toward the question of what can be known with certainty. Spinoza will take Descartes's definition of substance and draw from it what he regards as its necessary consequences: that there can be only one substance, and that this one substance is God or Nature.

Locke's contribution to the question of being is an epistemological one: he asks not what being is but what the mind can know about it. His investigation of the idea of substance in Book II of the Essay is among the most consequential passages in the history of the problem. We observe qualities, Locke argues, that tend to go together; we then suppose that some single thing underlies and supports them, because "not imagining how these simple ideas can subsist by themselves, we accustom ourselves to suppose some substratum wherein they do subsist." But this supposed substratum has no positive content in our minds: it is merely a "something, I know not what," a placeholder for the unknown bearer of qualities.

The Essay also draws a distinction between nominal and real essences. The nominal essence of a kind is the abstract idea we form by collecting the observable qualities that regularly accompany one another, and that we use as the criterion for applying a name. The real essence is the actual inner constitution of the thing, the microscopic structure from which the observable qualities flow. This real essence, Locke holds, is largely unknown to us: our science deals with nominal essences because real essences, even if they exist, are not accessible to our faculties. The question of what being ultimately is, at the level of real constitution, lies beyond the horizon of human knowledge.

The consequence of these arguments is a reorientation of the question of being. The great metaphysical question about the nature of substance cannot be answered by inspecting our ideas, since our idea of substance as such has no determinate content. What we can do is trace the relations among ideas, examine the co-occurrence of qualities, and draw probable inferences about the hidden causes of observed phenomena. The discussion of essence, substance, and the limits of human knowledge here connects with the broader questions treated under the ideas of Knowledge and Experience.

Berkeley will argue that Locke's admission of an unknowable material substratum is not merely an epistemic limitation but a conceptual incoherence. If the supposed substance underlying qualities contributes nothing to our knowledge and cannot be given in any experience, the concept of material substance as an independently existing thing is not an idea at all but an empty name. Whether the mind can coherently assert the existence of a being it acknowledges to be entirely beyond its grasp is the question Berkeley presses against Locke's position.

Spinoza takes Descartes's definition of substance as his starting point and holds that if substance is that which needs nothing else in order to exist, there can be only one substance. Two substances could not share an attribute without conflicting, and any finite thing is dependent on something else; so only the infinite, self-caused being satisfies the definition. That one substance Spinoza calls Deus sive Natura: God, or Nature.

Everything we call a thing, whether a mind, a body, or any other particular, is a mode of this one substance: a particular modification, seen under one of its infinite attributes. Of the infinite attributes, we know two: thought and extension. Mind and body are therefore not distinct substances, as Descartes held, but the same thing expressed in two different ways.

This monism removes the Cartesian problem of how thinking substance and extended substance interact, since they are not two substances but one. It also eliminates the classical hierarchy of being, in which God stands over and above the created order as its free cause. There is one Being, necessarily existing, of which the whole of reality is the expression. Finite things exist not apart from but as modifications of the infinite. The implications of this account for theology and for the understanding of God's freedom are treated more fully under the ideas of God and Necessity and Contingency.

Spinoza's conclusion that there is only one substance, necessarily existing, follows from premises that many of his contemporaries and successors accepted in part but declined to follow to this conclusion. Leibniz, who was acquainted with Spinoza's work, sought to preserve both the rational necessity Spinoza demanded and the plurality of individual beings, by means of his doctrine of monads.

Leibniz's account of being develops an alternative to both Cartesian dualism and Spinozist monism in the doctrine of monads. A monad is a simple, indivisible, immaterial substance: a unit of being endowed with perception and appetite. Each monad is windowless, having no real causal interaction with others; its states unfold entirely from its own internal principle.

What we call the physical world is a harmony of monads, pre-established by God so that their perceptions agree without any causal connection between them. Bodies are well-founded phenomena, aggregates of monads perceived together. Each monad mirrors the entire universe from its own point of view, and God is the monad of monads: the necessary being who chose this, the best of all possible worlds, from among all possible orders.

Leibniz also formulates the Principle of Sufficient Reason: nothing is without a reason why it is rather than is not. This principle, he argues, requires a necessary being as the ultimate ground of the contingent order, since only a being whose existence is its own reason can bring the regress to a close. The question of why there is something rather than nothing, which Leibniz is among the first to formulate explicitly, connects with the discussions of Cause and of God.

Leibniz's attempt to preserve individuality, plurality, and theological freedom within a rationalist metaphysics was subjected to criticism by Kant, who held that monads, as supersensible objects that cannot be given in any experience, lie beyond the limits of what human cognition can know. Whether the claims of rationalist metaphysics about being can be validated by the kind of experience that Kant regards as necessary for genuine knowledge is a question the Critique of Pure Reason puts at the center of subsequent discussion.

Berkeley draws out what he takes to be the necessary consequence of Locke's empiricism. Locke had granted that we have no positive idea of material substance, only a supposed unknown support of qualities. Berkeley argues that this is not a temporary gap in our knowledge but a permanent contradiction: the concept of a material being existing entirely outside all minds is one that cannot be formed. "It is indeed an opinion strangely prevailing amongst men, that houses, mountains, rivers, and in a word all sensible objects, have an existence, natural or real, distinct from their being perceived by the understanding." This opinion, Berkeley maintains, can survive only so long as it is not subjected to examination.

The principle esse est percipi governs sensible things: their being is their being perceived. This is not a skeptical conclusion but Berkeley's answer to skepticism. What we call the material world is not lost; the trees, mountains, and houses remain fully real as objects of perception. What is eliminated is the supposed layer of "matter" underlying perceptions, which no one has ever experienced, which serves no explanatory function, and which generates the very skepticism it was meant to prevent. Since we know only ideas, and material substance would be something entirely unlike an idea, it is not something we could ever know; therefore its existence is, on Locke's own principles, beyond our reach and should be abandoned.

God, for Berkeley, is the mind in whose perception the continuity and order of sensible things is grounded when no finite mind is perceiving them. The regular and intelligible order of nature expresses the language of God addressed to finite minds, not the workings of a mechanical substrate. Berkeley regards this account not as paradoxical but as common sense clarified: the world is as real as we take it to be, and no more. The implications of this dissolution of matter for the mind-body problem, and for the understanding of natural science, connect with the discussions under the ideas of Mind and Nature.

Kant will refuse Berkeley's identification of being with perception, insisting that what Berkeley calls the impossibility of matter outside minds is rather the impossibility of knowing things-in-themselves: things as they are independently of the conditions under which the mind apprehends them. The transcendental distinction between phenomena and noumena preserves what Berkeley denies, namely that there is something real beyond what is given in experience, while conceding what Berkeley asserts, namely that the mind is partly constitutive of the objects it knows.

Kant's contribution to the question of being centers on two related arguments. The first concerns the concept of being itself: "Being," he argues, "is manifestly not a real predicate." To say a thing exists does not add anything to the concept of the thing; it merely posits it. A hundred real thalers contain exactly the same concept as a hundred possible thalers, except that the real ones exist. From this it follows that the ontological argument for God's existence, which attempts to derive existence from the concept of a perfect being, fails; and with it, a considerable part of rationalist metaphysics.

The second argument concerns the limits of metaphysical knowledge. Kant distinguishes appearances (phenomena) from things-in-themselves (noumena). The mind imposes space, time, and the categories on experience; what we know are objects as they appear to us under these conditions. What things are in themselves, apart from our cognitive faculties, cannot be known by theoretical reason. The science of being as being, understood as a knowledge of what things are independently of the conditions of human experience, cannot therefore be established.

This does not abolish metaphysics altogether, but it changes its character. The categories become conditions of possible experience rather than features of things as they are. Freedom, God, and immortality are ideas of reason, necessary for practical life but not objects of theoretical knowledge in the way objects of experience are. The question of what being amounts to, after the Kantian critique, is taken up in different ways by Fichte, Schelling, and Hegel.

Hegel will argue that Kant's separation of thought from being, of the conditions of knowledge from the nature of reality, is itself a position that presupposes what it denies: that thought can in some sense reach being. Whether being is knowable through the movement of thought, or lies forever beyond the conditions of human experience, defines much of the philosophical debate following Kant.

Hegel's Science of Logic begins with the simplest possible concept: pure being, wholly indeterminate, with no content and no qualification. But pure being, on examination, proves indistinguishable from pure nothing: a being about which nothing can be said is equivalent, for thought, to nothing at all. Their truth is their movement into each other, which is becoming. From this initial movement, the subsequent categories of quality, quantity, and measure are unfolded by a dialectical procedure.

Hegel holds that the Kantian separation between the categories of thought and the nature of being cannot be sustained. The categories are not merely forms imposed by the mind on otherwise unknowable appearances; they are the self-articulation of Being and Thought, which are, at the level of the Absolute, the same. Reality is not a static hierarchy of substances but a dialectical process: every determination generates its opposite, and every opposition is overcome, or aufgehoben, in a richer whole.

The Phenomenology of Spirit traces this same movement as it appears in the development of consciousness. Spirit becomes what it is by passing through its own contradictions, recognizing itself finally as the totality. "The truth is the whole." Being, on this account, is not a first principle to be stated at the outset but a result to be achieved: the full self-knowledge of the Absolute, in which the distinction between thought and being is overcome.

Hegel's identification of being with the dialectical self-movement of thought was regarded by many of his contemporaries and successors as collapsing the distinction between logic and ontology. Whether the unity of thought and being he claims can be established by the procedure he follows in the Logic, or whether it is a presupposition rather than a result, remained a principal point of dispute in post-Hegelian philosophy.