Time

Plato gives the tradition its first great image of time. In the Timaeus, the Demiurge, contemplating the eternal Forms, wishes to make the visible world as much like them as possible. But the world is in motion, while the Forms are unchanging. So the Demiurge creates, along with the cosmos, "a moving image of eternity": time, which moves according to number.

Time and the heavens come to be together. The sun, moon, and planets are "instruments of time," their circular motions marking the days, months, and years that allow mortals to count and measure. Before the ordered motions of the heavens, there is no "before" and "after" properly speaking.

Time thus has a secondary, derivative status. The truly real is eternal and motionless; time is the best the sensible world can manage: an orderly, numbered shadow of the unchanging.

Plato installs the opposition of time and eternity that will structure the tradition. Aristotle will immediately press on the weakness in this account: if time requires an ordered cosmos, what was there before the Demiurge imposed order? Plato's answer (there was no "before") will not satisfy him, and the debate about whether time could have a beginning will run through Augustine, Aquinas, and Newton before Kant finally declares it unanswerable.

Aristotle gives the definition that dominates antiquity and the Middle Ages. After posing the puzzles (does time exist, since the past no longer is and the future not yet?) he answers: time is not motion itself, for motions vary and time is uniform; but time is not independent of motion either. Time is the number of motion with respect to before and after.

Where there is change, we distinguish earlier and later moments; by counting these, we have time. Time, therefore, requires both motion and a soul to count. Aristotle entertains whether time would exist without a numbering mind and leaves the question open: there would be the motion, but perhaps not the number.

The "now" is for Aristotle what binds time: it is the moving limit, always the same in character but always different in what it marks. Past and future are related through the continuity of successive nows. Time is thus continuous, infinite, and measured by the regular motions of the heavens.

Aristotle's definition of time as numbered motion remains the dominant philosophical analysis until the early modern period. But his admission that time may require a numbering soul opens a door he does not enter: Augustine will walk through it, arguing that time is not a feature of the cosmos at all but a distension of the mind itself.

Plotinus devotes Ennead III.7 to the relation of eternity and time, and ends by revising Plato. Eternity, he says, is not merely endless duration but the whole life of Intellect possessed simultaneously: "the life, instantaneously entire, complete, at no point broken into period or part." Time, by contrast, is the mode of life proper to Soul, which cannot possess itself all at once.

When Soul turned away from its restful contemplation of Intellect, it produced time as the unfolding of its own activity. Time is therefore "the life of the Soul in a movement of passage from one state to another": the interior, spreading-out of life that cannot remain gathered in the eternal Now.

This interiorizes time for the first time. It is not primarily the measure of celestial motion but the soul's own mode of existence. Augustine will seize on this, and the Western philosophy of time will become, in large part, a philosophy of the self.

Plotinus shifts the locus of time from the heavens to the soul, and opens the distinction between lived duration and cosmic measure.

Augustine's Book XI of the Confessions is the tradition's most famous meditation on time. He begins in perplexity: "What then is time? If no one asks me, I know; if I wish to explain it to one that asks, I know not." The past no longer is, the future not yet, and the present has no duration; so how can time be said to be?

His answer is interior. Time exists, but it exists in the mind. There are not properly three times (past, present, and future) but three presents: the present of things past, which is memory; the present of things present, which is attention (contuitus); the present of things future, which is expectation. When we measure time, we measure not things themselves but the impressions they leave as they pass through the mind.

This subjectivizes time decisively. Time becomes a dimension of the soul's life, not a feature of the external cosmos. And all of it stands beneath the eternity of God, who does not experience time at all but holds all moments in a single changeless present.

Augustine gives the Western tradition its phenomenology of time. The tension he leaves unresolved — between time as mind's measurement and time as something the created world really undergoes — will trouble Aquinas, who tries to give the cosmos back its own mode of duration, and Newton, who will insist that time flows absolutely regardless of any mind measuring it.

Aquinas synthesizes Aristotle and Augustine and adds a third mode. Time, with Aristotle, is the measure of motion and change, belonging to material things. Eternity, with Boethius and Augustine, is "the simultaneously-whole and perfect possession of interminable life," belonging to God alone. And between them is aevum, the mode of duration proper to angels and the separate souls, which are unchanging in substance but can change in their acts.

This threefold distinction preserves God's absolute eternity (not merely infinite time but the whole of life possessed at once), accounts for the ordinary time of motion, and makes room for creatures whose duration is neither temporal nor eternal. It also lets Aquinas answer disputes about creation: God's creative act is eternal, but what he creates is temporal and has a beginning.

Time, for Aquinas, is therefore real and measures real change, but it is not a container independent of things. It is the numbered succession that belongs to creatures capable of motion, and it ultimately presupposes the eternity from which creation proceeds.

Aquinas completes the classical-Christian synthesis on time. But his system depends on Aristotelian physics, and when Newton replaces those physics with an absolute time that flows without reference to any motion or any soul, the entire three-tier structure loses its scientific support and becomes a purely theological claim.

Newton gives time a new ontological status in the Scholium to his Principia. "Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external." It is an independent framework, not dependent on motion or on any mind, within which all events unfold.

Alongside this absolute time, Newton allows a "relative, apparent, and common time": the time we measure by clocks and celestial motions. But the real, mathematical time is absolute: a uniform stream whose duration would be the same whether anything existed in it or not.

This sharply departs from Aristotle, for whom time could not exist apart from motion, and from Augustine, for whom time was a feature of the mind. Newton's time is a container: infinite, uniform, and independent. It is the stage on which his mechanics plays out, and it becomes the scientific default for two centuries.

Newton elevates time to a kind of eternal, cosmic framework. Leibniz will attack this conception as needing no such thing, and Kant will transform it into a form of the mind.

Kant gives time its modern idealist turn. Against both Newtonian absolute time and Aristotelian time-as-number-of-motion, he argues that time is not a feature of things-in-themselves but a form of inner sense: the a priori condition under which the mind has any experience at all.

All our perceptions, inner and outer, are given in temporal succession. We cannot think them away from time; even when we imagine removing all objects, time remains as the very form in which we intuit. Time is therefore transcendentally ideal (belonging to the subject's sensibility) but empirically real (applying necessarily to every object of experience).

This explains how mathematics of time, and the necessity of temporal sequence, can be known a priori: they describe the structure of our sensibility, not of things-in-themselves. About the latter we know nothing. Things as they are apart from us are not in time; only appearances are.

Kant dissolves the old debate. Time is neither a container nor a relation of events but the form the mind brings to experience, without which no experience could exist.

Hegel reworks Kantian time by making it dialectical. In the Philosophy of Nature, time is the "pure form of sensibility" but also the concrete mode of negation in nature: each moment negates the last, passes into what it is not, and thus drives nature beyond itself.

In the Phenomenology, time becomes the medium in which Spirit works out its self-knowledge. "Time is the concept itself that is there." Spirit begins as merely temporal consciousness and, through the long historical development traced in the book, comes to grasp itself as absolute, at which point time is, in principle, comprehended and transcended. History is time thinking itself.

Hegel thus refuses the sharp Kantian divide between time as subjective form and things-in-themselves. Time is the way substance becomes subject; it is internal to the logic of reality, not merely a form of our perception. The rational is temporal because rationality must develop.

Hegel gives time a historical meaning Kant refused it. Time becomes the element of Spirit's self-actualization, and therefore of genuine novelty.

William James brings the philosophy of time down into psychology. The time we actually experience, he argues, is not the mathematical instant of physics but the "specious present": a felt stretch of a few seconds, with a core of immediate presence shading forward into expectation and backward into memory.

This specious present has duration given in it. We do not synthesize past, present, and future from isolated nows; we perceive change, motion, melody, directly, as wholes extended in time. The stream of consciousness flows; each pulse of thought includes more than a point.

James's analysis is empirical and phenomenological. He is skeptical of Kantian transcendental deductions but shares the inward turn: time as lived must be described from within the experiencing subject. And he reconnects lived time to Augustine: memory, attention, and expectation are not three different presents but features of the one specious present, the thickness of our felt now.

James gives the modern tradition its empirical description of lived time. Duration is primary; the instant is an abstraction from it.