The Paradox of Time from Aristotle to Modern Philosophy

Introduction

Time has puzzled philosophers for millennia. In everyday life we divide time into past, present, and future, yet this seemingly simple structure conceals profound metaphysical problems. Over two thousand years ago, Aristotle in Physics grapples with a paradox: how can time exist at all if it is composed of the past (which is no more), the future (not yet), and an infinitesimal present that has no duration? Aristotle’s analysis of this paradox – and his definition of time as “a number of motion in respect of before and after” – laid the groundwork for subsequent philosophical inquiry (Aristotle, 1984). The metaphysical implications of his view, such as the dependence of time on change and the status of the present “now,” have sparked extensive debate. This essay explores Aristotle’s paradox of time and its resolution, then examines how modern philosophers have responded to, expanded, or reinterpreted the paradox. We will consider those who explicitly engage with Aristotle (for example, Martin Heidegger, Henri Bergson, and J. M. E. McTaggart) as well as others who tackle the metaphysics of time in light of scientific and philosophical developments. The discussion is structured chronologically and thematically: first outlining Aristotle’s account and its implications, then tracing historical and modern perspectives, including comparative viewpoints, and finally reflecting on Aristotle’s enduring influence on the philosophy of time.

Aristotle’s Paradox of Time in the Physics

Aristotle’s analysis of time: In Physics IV.10-14, Aristotle presents a rigorous inquiry into the nature of time and directly confronts a seeming contradiction in its very being. He notes that “one part of [time] has been and is not, while the other is going to be and is not yet”, and yet time as a whole is said to be composed of these non-existent parts (Aristotle, Physics IV.10). This leads to an aporia or puzzle: “One would naturally suppose that what is made up of things which do not exist could have no share in reality.” (Aristotle, Physics IV.10). In other words, if neither past nor future truly exists, and if the present is merely a boundary with no extension, how can time itself exist? Aristotle articulates this paradox at the outset to frame the challenge any theory of time must address.

The “now” as a moving boundary: Central to Aristotle’s resolution is a careful distinction regarding the present instant or “now.” He argues that the now is not a part of time in the way that a segment is part of a line. “For what is ‘now’ is not a part: a part is a measure of the whole, which must be made up of parts. Time, on the other hand, is not held to be made up of nows.” (Aristotle, Physics IV.10). Rather than a constituent chunk of time, the now is like a point on a line – a boundary or limit that divides past and future. The now marks “before” and “after,” but it does not itself endure or add extension to time. Aristotle compares it to a point on a continuous line: just as a point has no length but merely divides a line, the present now has no duration but constantly divides time into past and future. This view avoids treating time as a sequence of atomic instants; instead, time is a continuum whose continuity is not composed of indivisible now-moments. The now is ever-changing – it “moves” in the sense that what was future becomes present and then past – yet there is never more than one actual now at a time. Aristotle considers the question of whether the now remains one and the same or is always changing; he concludes it must be perpetually “other and other” (each new moment a new now), otherwise all events would coincide in a single eternal present (Aristotle, 1984). Thus, the paradox is mitigated by understanding the now as a transitory marker rather than a substantive part of time.

Time’s dependence on change: A further metaphysical implication in Aristotle’s account is the intimate link between time and motion (or change). Famously, Aristotle defines time as “the number of motion in respect of before and after” – essentially, time is a kind of measure of change (Aristotle, Physics IV.11). He is careful to clarify that time is not identical with motion or change itself, but neither can time exist without changes. On one hand, any given motion can be faster or slower whereas time itself is uniform; on the other hand, if absolutely nothing changes (and even the mind registers no change), then no time is perceived to pass (Aristotle, Physics IV.11). He gives the example that if the soul (mind) does not notice any change, “we do not realize that time has elapsed” – as in the myth of sleepers who awaken not perceiving the long interval that passed (Aristotle, 1984). This suggests that time has no being per se independent of events; it is a measure relative to change. Aristotle concludes: “It is evident, then, that time is neither movement nor independent of movement.” (Aristotle, Physics IV.11). Time depends on the existence of change (there is no time in a completely static world), yet time is an abstract order or measure (the “number” of change), not a physical change itself. One consequence is that if the universe had no change at all, time would effectively not exist or “not be noticed” – a relational view of time that contrasts with later notions of time as an absolute container.

Metaphysical status of time: Aristotle’s resolution of the paradox gives time a peculiar ontological status. Time “barely” exists in that it is not a substance or entity, but an aspect of change recognized by a counting intellect. It is real inasmuch as change and the enumeration of change are real. Some commentators note Aristotle’s hint that if there were no conscious beings to count, there might not be time – “if nothing is able to count, there cannot be anything that can be counted,” implying time as countable requires a counter (Aristotle, 1984, IV.14). Thus, Aristotle flirts with the idea that time requires mind, though he stops short of fully making time subjective. Instead, he grounds time in the objective feature of motion: the before and after in movement provide a basis for the concept of earlier and later, which the soul can enumerate. By identifying time as a measure (arithmos) of motion, Aristotle effectively solves the original paradox: the past and future do not exist now, but they did exist or will exist at other “nows,” and the continuity of motion underlies the continuity of time. The present now has no duration, but time’s continuity comes from the unbroken succession of different nows and the persistence of change. In sum, Aristotle posits that time is real, but in a derivative sense – it is a relation or order of changes rather than an entity. This account carries significant metaphysical implications: time is continuous (infinitely divisible, never composed of indivisible atoms), time is relative to events (no events means no time), and the reality of time is tied to the existence of change and perhaps the perceiving mind. These themes – continuity, dependency on change, and the status of past and future – would deeply influence later thinkers and frame the classical understanding of time for centuries.

Historical Context: From Antiquity to Early Modern Views

Aristotle’s formulation did not occur in a vacuum; it was influenced by earlier Greek thought and in turn shaped subsequent views of time. To appreciate how modern philosophies respond to Aristotle’s paradox, it is useful to sketch the historical trajectory of ideas about time between Aristotle and the modern era.

Plato and ancient views: Prior to Aristotle, Plato had offered a famously poetic description of time in the Timaeus: time is the “moving image of eternity,” created together with the heavens (Plato, 2008). Plato’s emphasis was on an eternal realm of Forms in which true reality is timeless, whereas the physical world and its changes are temporal and less real. Aristotle’s stance can be seen as a departure from Plato’s — Aristotle grounds time in the natural world of change rather than in an otherworldly eternity. At the same time, Aristotle was wrestling with problems raised by Eleatic philosophers like Parmenides (who denied the reality of change) and Zeno’s paradoxes of motion. In this context, Aristotle’s insistence that change and time are real (against Parmenides), yet continuous and paradox-free (against Zeno), was foundational. His theory of time, tied to motion, became the dominant view in antiquity and through the Middle Ages, especially as it was integrated into the work of later Aristotelian philosophers.

Augustine’s subjective turn: A crucial development in the understanding of time came from St. Augustine of Hippo (4th–5th century CE), who directly engages Aristotle’s paradox from a psychological angle. Augustine reiterates the puzzle of past, present, and future: “the present of things past, the present of things present, and the present of things future” are all that really exist, because the past and future themselves are not now (Augustine, 1991). He famously remarks, “What is time? If no one asks me, I know; if I try to explain it, I do not know,” highlighting the elusive nature of time (Augustine, 1991). Augustine’s innovative contribution is to suggest that time exists in the mind as a stretching-out (distensio) of consciousness. The past survives in memory, the future exists in expectation, and the present is our immediate attention – thus, “the present of past things is memory, the present of present things is direct experience, and the present of future things is expectation.” (Augustine, 1991). By this account, the three modes of time are grounded in mental activities, which gives time a subjective, psychological reality. Augustine effectively internalizes Aristotle’s moving “now”: rather than an objective now sweeping along external events, it is the human mind that “measures” time by recording impressions of past, noting the present, and anticipating the future. He even asserts that when we measure duration, we are really measuring the impression in our own memory (Augustine, 1991). This view has strong metaphysical implications: time becomes not an external feature of the world but a feature of consciousness. Augustine’s perspective doesn’t so much refute Aristotle as reinterpret the paradox – he agrees that past and future are not in being, but he locates their being-in-a-sense inside the soul. This idea prefigured later philosophies (notably Kant and phenomenology) that treat time as dependent on the perceiver. It also raised questions about objective time versus experienced time that continue into modern debates.

Medieval and scholastic considerations: Medieval thinkers, largely influenced by Aristotle via scholasticism, adopted Aristotle’s definition of time while also considering theological issues. Thomas Aquinas, for example, follows Aristotle in saying time is the measure of movement and insists that without change time would not be noticed (Aquinas, 1964). However, a Christian framework introduced the idea of a beginning of time (at Creation) and God’s eternity (being outside time). Aristotle had argued that time is eternal in both directions – he thought time could have no beginning or end because any boundary of time would be a “now,” which cannot exist in isolation (Aristotle, Physics VIII.1). Aquinas reconciled Aristotle with theology by suggesting that while reason alone might see no necessity for a beginning of time (the world could be eternal), revelation tells us time did begin. This gave time a contingent status: God created time along with the universe. Such discourse kept Aristotle’s paradox in play under new guises (e.g., “what was God doing before creation?” – a question Augustine famously dismisses by saying “there was no time before time began”). Overall, through late antiquity and the Middle Ages, Aristotle’s view that time requires change (and perhaps a soul to count) remained influential, tempered by theological considerations of eternity and creation.

Newton and absolute time vs. Leibniz and relational time: The early modern period saw a dramatic shift with the rise of modern science. Sir Isaac Newton in the 17th century formulated a concept of time that broke from the Aristotelian relational view. Newton posited absolute time as a real thing in itself: “Absolute, true, and mathematical time, of itself and from its own nature, flows equably without regard to anything external.” (Newton, 1999). In Newton’s mechanics, time is like an independent background parameter, a container through which events occur, even if nothing is happening. This conception treats time as an entity (or at least an independent dimension) that would continue to pass uniformly even in a completely empty or unchanging universe. The paradox of time’s composition is sidestepped by postulating that instants of time exist objectively; the present is simply one point on a fixed timeline and past/future points are just as real in the structure of time (even if not “active” now). Newton thus abandons Aristotle’s idea that time is a measure of change – instead, change is measured by absolute time. This was a revolutionary metaphysical shift that implicitly nullified Aristotle’s paradox: if time is an absolute flow, one need not worry that it is “made of non-being” – time simply is, as a fundamental aspect of reality.

Not everyone accepted Newton’s view. Gottfried Wilhelm Leibniz, Newton’s contemporary, argued for a relational theory more in line with Aristotle and Augustine. Leibniz insisted that time and space have no existence apart from objects and events; they are orders of relations. In a famous correspondence with Samuel Clarke (a defender of Newton), Leibniz wrote that if God “removed all the matter in the world along with its motions,” space and time would not exist except ideally, since they are not “absolute realities” but systems of relations (Leibniz, 1715). For Leibniz, to ask “when” something happens is to situate it in relation to other events. Time is an order of succession, not a thing that flows on its own. Thus, “motion could be without time” if no mind perceived it, he even suggests, echoing Aristotle’s notion that time is the numbering of motion (Leibniz, 1715). The Newton-Leibniz debate sets up a clear contrast: absolute vs. relational time, a dichotomy that maps onto whether time is an independent reality or a dependent measure. Aristotle’s position is firmly on the relational side (time depends on change and perhaps on being counted), and Leibniz explicitly aligns with that, while Newton’s side creates a new framework in which Aristotle’s paradox is less pressing (because time is a real uniform continuum akin to an infinite line of instants).

Kant’s critical philosophy of time: Immanuel Kant, in the late 18th century, offered another profound reimagining of time’s metaphysical status. In his Critique of Pure Reason (1781/1787), Kant agrees with Newton that time (and space) is not derived from experience of objects – but he does not conclude that time is an absolute substance or container. Instead, Kant declares that time is an a priori form of sensible intuition inherent in the human mind (Kant, 1998). According to Kant, time is essentially the framework within which we intuit phenomena; it is not a feature of things-in-themselves, but of our mode of experiencing. This move internalizes time similar to Augustine, yet in a transcendental rather than empirical way. Kant argues we cannot perceive or imagine events except in temporal sequence – the mind imposes temporal order. Hence, statements like “past and future are not real” are, for Kant, both true and false: in terms of things-in-themselves (ultimate reality beyond our perception), time does not exist (so asking if the universe “really” has a past or future is meaningless beyond phenomena). But in terms of appearances, time is very much real – it is the condition for anything to appear at all. Kant thereby sidesteps the ontological paradox by treating time as ideal: it has reality only as part of the structure of consciousness and experience. He famously notes that time is not a concept we abstract from experience, but a pure intuition that prefigures any experience (Kant, 1998). This builds on Augustine’s insight that time is tied to the mind, but Kant universalizes it: every subject must experience in time. It also means that certain metaphysical puzzles – like whether time had a beginning – cannot be settled by reason about things-in-themselves. (In fact, Kant’s First Antinomy of pure reason features a thesis that “the world has a beginning in time” and an antithesis that “it is infinite in time,” and he shows how each can be argued for, concluding the dispute is resolved once we realize time is only a form of intuition, not an attribute of the world in itself (Kant, 1998).) In Kant’s framework, Aristotle’s empirical observation that we only perceive time when change is noticed is recast: without the mind’s intuition of time, we would not organize any perceptions at all. Time becomes a necessary pre-condition of experience rather than an observable measure of motion. The metaphysical implication is a form of idealism about time: it doesn’t exist “out there” in the objects, but it is an invariant of the subject’s perspective.

By the end of the 18th century, then, we see a spectrum of views influenced by or reacting to Aristotle’s paradox: Presentism (only the present exists in reality, as Aristotle’s analysis seems to suggest) versus eternalism or absolutism (time is a real continuum like Newton’s, comprising past, present, future equally in some sense). Also, relationism (time depends on events, akin to Aristotle/Leibniz) versus idealism (time depends on the mind, Augustine/Kant). These debates set the stage for the 19th and 20th centuries, when new paradoxes of time were formulated and Aristotle’s ideas were revisited in light of modern science and logic.

McTaggart’s Argument: The Unreality of Time

Early in the 20th century, the British idealist J. M. E. McTaggart offered a bold and influential new paradox about time’s existence, one that in some ways echoes Aristotle’s concerns but arrives at a startling conclusion: time is not real. In his 1908 paper “The Unreality of Time,” McTaggart presents a rigorous metaphysical argument that has shaped much of the modern philosophy of time. His argument introduces the distinction between two ways to order events in time, which he calls the A-series and the B-series (McTaggart, 1908).

• A-series (dynamic time series): This is the ordering of events as past, present, or future. In the A-series, positions in time are defined by moving attributes: an event will be future, then it becomes present, and then past. The A-series embodies the flow or passage of time, since events constantly change their A-series characteristics (what is now present will soon be past, etc.). This roughly corresponds to our tensed view of time and the everyday notion of time passing. It also corresponds to Aristotle’s idea of a moving “now” – the A-series tells us where the now is and which events lie ahead or behind.

• B-series (static time series): This is the ordering of events by the earlier-than/later-than relation. In the B-series, each event has a fixed position relative to others (for example, Event X is 100 years earlier than Event Y). This ordering does not change; it is a permanent sequence of events. Saying “X is earlier than Y” is tenseless – it does not depend on any moving present moment. The B-series is like a timeline on which events are laid out in a fixed order but without designating an objective present. If we think of time as a fourth dimension, the B-series captures that four-dimensional ordering.

McTaggart argues that both series are essential for time to be time. The B-series alone gives a sequence but no sense of “change” or flow – it’s like a static picture where all events are equally real (akin to Newton’s or Einstein’s time as a dimension). Real change, McTaggart insists, involves events coming into the present and moving out to the past, which is the A-series feature (McTaggart, 1908). In fact, he defines real change as a change in an event’s properties from future to present to past. For example, the event of your birth was future, then present at the moment it happened, and is now many years past – that transition is what it means to undergo temporal change. Without an A-series, events would just be earlier or later than each other, and nothing would ever genuinely “become” (McTaggart, 1927). On this basis McTaggart sets up the paradox:

1. If time is real, the A-series must exist (because time’s reality requires genuine change, and change requires the passage from future to present to past). McTaggart takes this as a premise: time requires an A-series (McTaggart, 1908). This is actually similar in spirit to Aristotle’s view that time implies change – McTaggart specifically says a mere B-series (which is essentially a tenseless ordering) cannot account for the presence of change or the distinction of past vs future, just as Aristotle argued that without the “now” and the distinction of before/after, time would not be noticed.

2. But the A-series is self-contradictory. McTaggart’s most famous contribution is attempting to prove that the A-series concept leads to a contradiction. His reasoning (simplified) is: Each event in time possesses all three A-series determinations: it will be future, it will be present, and it will be past (at different times). These properties are mutually exclusive if taken at one time (an event cannot be simultaneously present and future, etc.). One might say, “Well, they have them at different times,” but that “at different times” presupposes time (a second time-dimension) to explain the change of A-properties – leading to an infinite regress of times within time (McTaggart, 1908). In other words, to avoid contradiction we’d have to say an event is present in the present, past in the future, etc., which is a convoluted way of saying we need a meta-time in which the event’s A-character changes. No matter how you slice it, he argues, the concept of events moving from future to past cannot be made coherent: it forces us to say an event has all three properties (since every event will be present at one time, was future at one time, will be past later), and that is a contradiction unless we introduce an endless hierarchy of time to sort out when it has which property (McTaggart, 1908). This is sometimes called “McTaggart’s paradox.” It mirrors Aristotle’s concern (past and future are not real, yet we speak of them) but pushes it further by formal logic: the tensed description of time seems logically inconsistent.

From these steps, McTaggart concludes that time is unreal. If time requires the A-series and the A-series is impossible, then genuine time cannot exist. What we call “time” must be an illusion or appearance of something more fundamental. (Indeed, McTaggart, being an idealist, believed ultimate reality was a timeless network of spiritual relations, and time’s appearance is a sort of false way of organizing those relations.)

McTaggart’s argument sent shockwaves through 20th-century metaphysics. Many disagreed with his conclusion but felt compelled to address the issues he raised. In effect, McTaggart posed a challenge: either find a way to make sense of the A-series (the reality of past-present-future and temporal becoming) or else accept a view of time that dispenses with it. This led to the famous division in modern philosophy of time between tensed (A-theory) and tenseless (B-theory) views of time, and relatedly between presentism (only the present is fully real) and eternalism (past, present, future are equally real in a “block universe”).

• Philosophers who retain something like the A-series (often called A-theorists) argue that temporal becoming is a fundamental aspect of reality. For example, some adopt presentism, the view that only present entities exist in an ontologically robust sense (the past has slipped out of being; the future is not yet). This is quite congenial to Aristotle’s original remarks that “of time some parts have been, others are to be, and no part of it is” – which practically reads like a presentist slogan (Aristotle, Physics IV.10). Presentists respond to McTaggart by denying that events “have” past or future properties in any absolute sense – only presentness is an actual property (and what is past did exist but does not now). They thereby try to avoid the contradiction by not assigning reality to past or future events at the same ontological level as the present. However, presentism faces other challenges (such as how to account for truths about the past or the rate of time’s passage), which keep the debate active.

• On the other side, many philosophers influenced by McTaggart’s critique (and by the physics of relativity) have embraced B-theory or eternalism, treating time as a four-dimensional block of events without an objective present. In this view, all moments exist, and “past” or “future” are like “here” or “there” – relative terms depending on perspective. An eternalist says: the event of Aristotle writing the Physics exists at its proper time (somewhere in 4th century BCE); it was present then and is past now only from our later vantage point, but all events are equally part of the spacetime continuum. This stance basically accepts McTaggart’s rejection of an objective A-series – it says the flow of time or the moving now is an illusion or a subjective aspect, not an ontological feature of the world. Time is thus real as the B-series (ordering of events), but not as an ever-changing present. While this avoids the logical contradiction McTaggart noted, it arguably comes at the cost of denying the manifest experience of time passing.

McTaggart himself was willing to bite the bullet that time (as commonly understood) isn’t real at all. Later philosophers have generally taken a less radical path, either revising the concept of time to exclude a moving present (B-theorists) or upholding a version of the A-series and trying to refine it (A-theorists). Importantly, his argument forced even those who disagreed to refine their metaphysical accounts. For instance, some philosophers distinguish between A-facts and B-facts, or propose dynamic theories of time (the “growing block” theory, in which the past and present exist but the future doesn’t yet, etc.) in an attempt to consistently accommodate a changing present.

In summary, McTaggart expanded Aristotle’s paradox of non-being in time into a formal argument that the passage of time is logically incoherent. Where Aristotle resolved the paradox by making time a measure of motion (hence real but dependent on change and the now), McTaggart, using a more austere logic and idealist framework, resolved it by denying time’s reality altogether. This stark conclusion provoked vigorous responses in 20th-century metaphysics. The metaphysics of time became a specialized field, dissecting questions like “Is only the present real?”, “Does time flow or is it humans that ‘move’ through a static time?”, and “Can we make sense of past and future existence?”. In all these debates, we can see the shadow of Aristotle’s original questions about the reality of past and future, and the nature of the present. McTaggart’s modern paradox thus carries forward Aristotle’s legacy into contemporary terms, and any adequate theory of time must show either why the paradox is mistaken or how to live with its consequences.

Bergson’s Philosophy of Duration

While McTaggart’s approach used abstract logic to question time’s reality, another major modern approach to time came from the French philosopher Henri Bergson, who focused on lived experience and the qualitative nature of temporal process. Bergson directly tackled the metaphysical nature of time by distinguishing between what he called “mathematical time” (the time of clocks and science, composed of distinct instants) and “duration” (la durée), which is time as we truly experience it – continuous, interpenetrating, and qualitative (Bergson, 1910). In doing so, he effectively expanded and reinterpreted Aristotle’s paradox, critiquing the very way we commonly conceive of time as a series of divisible moments.

Time and spatialized thinking: Bergson observed that we have a habit of “spatializing” time – we represent time as a line of separate points or as a sequence of distinct units (seconds, minutes, hours). This view treats time like a homogeneous medium made up of instants analogous to points in space. Bergson argues that this is an imposture of the intellect on the reality of time. He notes that in science (and even in Aristotle’s definition), time is often treated as a measure of motion, essentially converting time into a series of countable units. But for Bergson, this misses the essence of real time. He famously stated: “The line we draw to represent time is stationary, but time itself is mobile. The line is already made, but time is what is in the making, or better, what makes itself. The measure of time does not capture duration as it is lived.” (Bergson, 1910). In this quote, Bergson is pointing out that any attempt to measure time (for instance, by clock ticks or by subdividing it) involves treating time as if it were a completed line of identical segments. This is fundamentally different from the flowing, creative nature of real duration, which is never complete or composed of identical units.

Duration (la durée): Bergson’s concept of duration refers to the experienced flow of time, which is characterized by heterogeneous moments melting into each other. In pure duration, the past does not vanish but rather continues in the present in an altered form, and the future is emerging. He gives the example of listening to a melody: if time were truly a series of separate instants (notes heard one by one in isolation), we would never hear a melody – we would hear a disconnected series of sounds. But in reality, when listening to music, the notes blend; the sound just heard lingers in memory and is carried into the next, creating a continuity and interpenetration. This, for Bergson, exemplifies real time. The present has some thickness – we can be aware of just-past notes as present memory. Thus, “when we speak of the present, we instinctively extend it a little into the past… Our consciousness tells us that the so-called present is really a somewhat indeterminate interval of duration – something elastic, not a mathematical point.” (Bergson, 1910). Bergson here directly addresses Aristotle’s paradox of the present’s non-duration: he would say the paradox arises only if we conceive the present as a mathematical instant. In lived experience, the present is not an indivisible now-point but an accumulation of a moment that endures. The paradox dissolves because the past is not absolutely gone – it survives in memory and in the state it creates in us, and the present is not merely a knife-edge, it has internal duration.

Metaphysical implications: Bergson contends that reality is continuous creation, an “undivided growth” of duration. The divisions we make in time are practical conveniences but not ultimately real. For him, the flow of time is the fundamental stuff of the universe, especially of conscious life. He even extends this to a cosmic principle in works like Creative Evolution (1907), where evolution is driven by an élan vital (vital impulse) that is inherently temporal and creative, not mechanical. Bergson explicitly criticizes the Aristotelian (and generally scientific) notion that time is just the measure of motion. He argues that Aristotle’s analysis, while not entirely wrong, deals with the quantitative aspect of time (the countable aspect, the measure) and thereby aligns with what Bergson calls “mathematical time” or “clock time.” But Bergson insists that this misses the qualitative, metaphysical aspect of time as felt duration (Ortiz de Landázuri, 2020). In his view, Aristotle’s definition explains how we construct the idea of time by counting motion (which is akin to how physics treats time), but it does not capture time as it is in itself. In fact, Bergson would say that to treat time as a series of static moments (like separate “nows” or slices) is to substitute space for time – one imagines those moments laid out side by side (like marks on a line) which is a spatial image, not temporal reality.

By reinterpreting the nature of the present and the continuity of past-present-future, Bergson offers a solution to Aristotle’s paradox quite different from McTaggart’s. Instead of declaring time unreal, Bergson declares mathematical time unreal (or at least an intellectual abstraction) and asserts the reality of experienced duration. He maintains that the past and future in a sense are real – not as distinct existences, but as an enduring influence or an impending novelty. The past lives on in the present (hence it is wrong to say it absolutely is not), and the future is in continuity with the present (hence time is an ongoing creative process, not a predetermined line).

This view had wide influence, especially in continental philosophy and literature, and even in psychology. It resonated with William James’ idea of the “specious present” (the short duration we directly experience) and influenced Marcel Proust’s literary exploration of time and memory. Metaphysically, Bergson’s idea of duration has often been seen as a forerunner to process philosophy (e.g., Alfred North Whitehead) and to existential and phenomenological explorations of time (such as Heidegger’s, discussed below).

It’s worth noting that Bergson also engaged with modern science: in Duration and Simultaneity (1922), he famously critiqued Einstein’s theory of relativity’s treatment of time, arguing that relativity’s notion of multiple observers’ times only makes sense against a background of a fundamental duration that is not relative. While many physicists and philosophers of science think Bergson misinterpreted relativity, the debate highlighted the tension between a physics that leans toward a tenseless, block-universe conception of time and Bergson’s insistence on an intrinsic flow. Einstein himself responded to Bergson, effectively siding with the block universe and saying “the time of the philosopher” (Bergson’s duration) had no place in physics (Einstein/Bergson debate, 1922). Nonetheless, many later philosophers (especially in phenomenology) echo Bergson’s emphasis that whatever physics says, the phenomenon of temporal passage is a basic datum of our being.

In summary, Bergson reinterprets Aristotle’s paradox by denying that time is made of static, non-existent parts at all. The error, in Bergson’s eyes, was ever imagining time as divisible into independent pieces (past, now, future). Instead, time is an indivisible growing continuum – a duration in which past and present coexist dynamically. His work thus expands the metaphysics of time to include not just logical and physical considerations, but the qualitative, felt aspect, arguing that any true philosophy of time must do justice to this lived reality.

Heidegger’s Reinterpretation: Temporality and Being

Martin Heidegger, one of the 20th century’s most important philosophers, directly grappled with the concept of time in the wake of the traditions from Aristotle through to Augustine, Kant, and beyond. In Being and Time (1927), Heidegger makes temporality a centerpiece of his existential analytic of human existence (Dasein). Heidegger explicitly credits Aristotle as inaugurating the traditional concept of time, which he sometimes calls the “vulgar” or ordinary conception, and then seeks to dig deeper to what he calls originary temporality. His approach thus is not merely to solve Aristotle’s paradox but to radically reframe it: he asks how the very understanding of Being is tied to time, and he distinguishes different levels at which we speak of time.

Time as a fundamental ontological horizon: Heidegger starts from the idea that our understanding of being (the existence of entities) is intimately tied to time. He echoes Kant in saying time is the “condition of the possibility” of our understanding of being, but he goes further: “Time is the possible horizon for any understanding whatsoever of Being.” (Heidegger, 1962). In other words, we only comprehend beings as beings (with meaning, functions, etc.) because we exist temporally; past, present, and future contexts give things significance. This shifts the discussion from what time is to what time does for intelligibility.

Critique of the traditional concept (Aristotle’s time): In Heidegger’s view, since Aristotle the West had largely understood time in a certain way: as a series of now-points, a sequence that can be counted – essentially, time as a linear continuum like a container for events (Heidegger, 2010). He notes that Aristotle’s definition – time as the number (count) of motion with respect to before and after – underlies what later became the common sense and scientific view of time (Heidegger, 1982). This view considers time as something like a dimension composed of “nows” that one could, in principle, map out. Heidegger refers to this as “world-time” or sometimes “within-time-ness” – time as a framework where entities occur in succession. It is similar to what Bergson criticized as spatialized time, and indeed Heidegger recognizes that the ordinary concept treats time as something present-at-hand, as if we could say time consists of a sequence of present moments strung along.

Heidegger argues that this ordinary concept, while valid in daily life and science, is derivative. He asks: what makes it possible for us to have this sequence of nows, to measure them, to be aware of before and after? His answer is that underlying this is a more primordial temporality rooted in human existence (Dasein).

Originary Temporality (Temporalität) vs. ordinary time: Heidegger distinguishes multiple levels of time (Heidegger, 1962; Wrathall, 2025):

• Originary temporality (Temporalität): This is the deepest level – an ontological structure of Dasein (the being that we are). It is not a sequence of nows at all, but a unity of what Heidegger calls the “ecstases” of time: the future, past, and present understood as existential orientations. Dasein is characterized by being stretched along: it is always ahead-of-itself (projecting into possibilities, essentially future), already in a world with a given heritage or thrownness (having a past or has-been aspect), and presently alongside entities (engaging in the now) (Heidegger, 1962). These are not three distinct times but three facets of a single unified phenomenon of temporality. Heidegger describes this as “a future which makes present in the process of having been” – meaning the future (our aims, purposes) and the past (our background, where we come from) converge in making the present what it is (Heidegger, 1962). This tripartite structure is compared to Augustine’s threefold present (Augustine’s influence is explicitly acknowledged by Heidegger). Importantly, originary temporality is not a succession of moments; it is more like a field in which Dasein exists, always projecting forward, drawing on its past, and enacting in the present.

• Derivation of world-time: From this originary temporality, according to Heidegger, arises the notion of time as a series of nows. When we disengage from our absorbed practical activity and observe or measure, we conceive of a uniform sequence (seconds on a clock, etc.). This yields what Heidegger calls “world-time”, which is essentially the time Aristotle described: a single timeline, divisible into now-points, which we use to date events and synchronize the world (Heidegger, 1962). Heidegger says world-time is “public” and “datable” – we can say an event happened at such-and-such clock time, the sun rises at 6:00, etc. This is the time that clocks measure, and it treats all “nows” as identical, differing only in position.

• Within-time-ness: Entities within the world are “in time” in this ordinary sense (they occur, endure, change in the timeline). This is an important notion because it allows a distinction: Dasein exists temporally (in the originary sense), whereas present-at-hand objects persist in time (in the ordinary sense). Traditionally, philosophers treated the being of things as presence in the now (what Heidegger calls the “metaphysics of presence,” tracing back to Greeks interpreting Being as what is present). Heidegger argues that Aristotle’s view of time contributed to this focus on present presence (since time was often reduced to the measurable present moment and its relations).

Heidegger’s reinterpretation of Aristotle’s paradox would go like this: The reason we find time paradoxical (past unreal, future unreal, present fleeting) is that we have interpreted time only at the level of world-time. We then wonder how this framework itself exists. Heidegger would say that underlying the idea of past, present, future as separate is the deeper reality that Dasein exists such that its being is temporal – it lives toward the future, already-coming-from its past, in a present engagement. Past and future, in the existential sense, are not unreal at all: they are “equiprimordial” aspects of our being. The past (what Heidegger calls having-been or Gewesensein) is carried with us as who we have become; the future (Zukunft) is alive as our projects and possibilities (e.g. being-toward-death, our finitude, shapes our choices); the present (Gegenwart) is the moment of vision or action where things get articulated (Heidegger, 1962). These are real, not in the sense of present-at-hand substances, but as structural moments of existence. Thus, to rephrase Aristotle’s paradox: the past and future in the sense of world-time do not exist now – yes – but the past and future in the sense of temporality are always part of existence. Heidegger thus gives metaphysical weight back to past and future by seeing them as more than mere “no-longer” and “not-yet.” He writes, “Time [temporality] is not a sequence of now-points… Originary temporality consists in the coming-towards (future), the having-been (past), and the making-present, which constitute the unity of the ecstases of temporality.” (Heidegger, 1962).

Another way Heidegger addresses Aristotle’s puzzle of the now is by noting that presence is only one mode of time. Western philosophy, since Aristotle, had a tendency to privilege the present – to think that only the now is fully real (this is inherent in Aristotle’s notion that only the now in some way “is”, since past and future are not). Heidegger terms this an “inauthentic” view when taken as the ultimate truth. In contrast, Heidegger’s authentic temporality has no single privileged now – the present is meaningful only in relation to the past and future that contextualize it. The now is a kind of abstraction or a freeze-frame from the fluid temporality of life.

Heidegger explicitly engages Aristotle in some of his lectures (for instance, The Basic Problems of Phenomenology (1927) and History of the Concept of Time (1925)). He notes that Aristotle’s definition already contains a critical insight: time is not just motion, it’s something like making motion countable. This hints at a transcendence beyond mere physical change. But Heidegger believes Aristotle (and the tradition following) did not interrogate what allows counting and distinguishing of “before” and “after” in the first place – which for Heidegger is our temporality. He also faults Aristotle’s view for implicitly relying on a concept of the constant presence of the now. Aristotle struggled with whether the now is always one and the same or always different; Heidegger would say this problem doesn’t arise at the level of temporality, because the “now” as such isn’t fundamental – it’s a feature of world-time that humans project from their deeper temporal being.

In Being and Time, Heidegger uses these ideas to reinterpret many classic philosophical issues. For example, he discusses death as the consummation of Dasein’s temporality (one’s own death is the ultimate future that defines one’s life possibilities), and historicity as the way Dasein’s past (heritage, tradition) is appropriated. Thus, time is not a backdrop but the fabric of human meaning. This is a dramatic expansion of the significance of time: whereas Aristotle saw time as dependent on things (motion, change), Heidegger sees Being (how things are disclosed) as dependent on time. In effect, he inverts the priority: rather than time arising from motion, for Heidegger motion or change (and even scientific time) arises from an entity (Dasein) that is itself temporalizing.

Influence and implications: Heidegger’s temporal philosophy strongly influenced existentialism and phenomenology. Thinkers like Jean-Paul Sartre took up the idea that human reality is time, emphasizing our projects and choices (future-oriented) and facticity (past). Heidegger also built a bridge back to Augustine and Kant. He praised Augustine’s insight into the threefold present and clearly took inspiration from it in formulating ecstases of temporality. He also considered himself fulfilling Kant’s project by revealing how time is the basis of the understanding of being (Heidegger, 1927). Additionally, Heidegger’s work influenced interpretations of Aristotle in the 20th century, prompting scholars to revisit Aristotle’s texts on time with an eye to distinctions like ontological vs ontic time.

For the paradox of time, Heidegger provides a nuanced answer: The reason time seems paradoxical (as Aristotle noted) is because we treat “time” as if it were a thing like other things (countable, present, composed of parts). In reality, time is more fundamental; it is “outside” the usual categorization of entities. Past and future are not mere negations of presence but active dimensions of being. The fleeting present is not an isolated reality but part of a temporal stretch. By relocating time from the domain of objects to the domain of being, Heidegger simultaneously preserves what is correct in Aristotle’s account (the importance of before/after and the unity of time with events) and transcends its limitations by saying the primary phenomenon is not the ticking of the clock or the motion of a star, but Dasein’s temporal existence from which those concepts get their sense.

In summation, Heidegger expands Aristotle’s inquiry into a full-blown ontology of time. Where Aristotle asked, “Does time exist and what is it?”, Heidegger asks, “How is being fundamentally temporal, and how have we come to think of time as we do?” This shifts the focus from solving a puzzle about an entity called time to understanding how time constitutes the meaning of everything we experience. Yet, Aristotle’s influence is unmistakable in Heidegger’s framework, serving as both a point of departure and a foil that Heidegger reinterprets.