On partial eternity
Finitude, infinity and the direction of time
The notion of ‘eternity’ carries with it an almost gravitational weight, a conceptual density accumulated over millennia of theological dispute, metaphysical speculation and cosmological inquiry. Its classical formulation, inherited largely from the Greeks and solidified in medieval scholasticism, presents eternity as an unbroken, infinite expanse stretching without limit into both the past and the future. Eternal, in this enduring view, means to have existed always and to persist always. It is a state of complete temporal plenitude, unbounded in either temporal direction. Yet, a quiet but persistent counter-intuition nags at the edges of this grand conception: Why must existence beginningless to be truly endless? Why cannot a thing emerge, distinctly and finitely, from the flux of non-being or causation and then persist, unchanging or enduring, for all future time? This notion, of a semi-eternity, an existence finite in its past duration yet infinite in its future persistence, presents a compelling and scientifically resonant, alternative to the classical model. It disentangles the concept of endlessness from the burden of “beginninglessness”, offering a framework that accommodates both cosmic origins and ultimate endurance.
The classical ideal of bidirectional eternity finds its most potent expression in Aristotle’s conception of the Unmoved Mover. This prime cause, necessary to avoid an infinite regress of causation Aristotle deemed impossible, must itself be uncaused and therefore without beginning. Its perfection necessitates immutability and thus endlessness. It exists, as Boethius would later crystallize for the Christian tradition, in the totum simul, the simultaneous and complete possession of interminable life, entirely outside the successive flow of time experienced by mortals. Eternity, in this exalted sense, is fundamentally atemporal or supratemporal; it inhabits a mode of being categorically distinct from the ‘before and after’ of temporal becoming. Thomas Aquinas, synthesizing Aristotle with Christian doctrine, rigorously defended this view, arguing that God, as pure act without potentiality, must be entirely free from the succession inherent in time. Any hint of temporal extension, even infinite extension, would imply potentiality and thus imperfection. For the classical theist and the Aristotelian metaphysician alike, true eternity was synonymous with timelessness or an infinite, undifferentiated duration encompassing all possible temporal moments at once.
This conception, however, encounters formidable obstacles when translated from the rarefied air of pure metaphysics into the contingent realm of physical existence or even abstract entities considered within time. The primary difficulty lies with the concept of an actual infinite past. While mathematics handles infinities with remarkable dexterity, Cantor’s transfinite numbers stand as a testament to this, the application of an actualized temporal infinity to the physical world or to causal sequences generates persistent paradoxes. How does one traverse an infinite series to arrive at the present moment? If the past is truly infinite, then an infinite sequence of events must have already occurred to bring us to ‘now’. Yet, the very definition of an infinite series is that it cannot be completed by successive addition. We find ourselves, as many philosophers from al-Kindi to contemporary thinkers like William Lane Craig have argued, confronting the seemingly insurmountable problem of forming an actual infinite by successive addition. It appears akin to counting down from negative infinity to zero; the task is not merely Herculean, but logically incoherent. The notion of an infinite past thus carries a persistent scent of paradox, a mild but persistent intellectual vertigo that the concept of a finite past deftly avoids.
Enter the proposition of semi-eternity or future-infinite existence. It proposes a model of enduring being that sidesteps the pitfalls of the infinite past while retaining the essential quality of endless persistence. An entity comes into being at a specific point in time, *t*. Prior to *t*, it does not exist. Its past is finite, bounded by its moment of origin. From *t* onwards, however, it persists indefinitely. Its future is unbounded; it will exist at every moment succeeding *t*, forever. This structure possesses an elegant simplicity and a striking compatibility with our dominant scientific narrative of cosmic origins. The standard Big Bang model posits a definite beginning for spacetime itself roughly 13.8 billion years ago. Prior to this singularity (or quantum state), the concepts of ‘before’, ‘time’ and even ‘existence’ as we understand them may lack meaning. The universe, in this model, has a finite past. Current cosmological models then offer various futures: a Big Crunch (finite future), perpetual expansion approaching heat death (effectively infinite future in terms of persistent, albeit entropically degraded, structure) or cyclical models. Crucially, the scenario of perpetual expansion, an ‘open’ universe, aligns precisely with the concept of semi-eternity: a finite origin followed by an effectively endless future duration. The universe, in this view, becomes a semi-eternal entity. It did not exist forever in the past, but it may well exist forever in the future. The grandeur of its potential endlessness is not diminished by its having had a beginning; indeed, the fact of its origin arguably makes its subsequent endurance all the more remarkable.
This model necessitates a refinement of terminology. The classical, weighty word ‘eternal’ often carries the baggage of “beginninglessness”. To apply it unmodified to a semi-eternal entity invites confusion and risks diluting its specific historical meaning. Precision demands alternatives: semi-eternal, explicitly denoting the one-sided infinity; future-infinite, a starkly descriptive term emphasizing the direction of unboundedness; or perhaps post-originally perpetual. The entity itself might be described as possessing endless endurance or infinite futurity, terms that capture the core idea without implying an infinite past. This linguistic precision is not mere pedantry; it clarifies the conceptual landscape, preventing the conflation of distinct metaphysical categories. It acknowledges that while a semi-eternal entity lacks the tota simul perfection of the classical eternal, its existence from its origin onward possesses a unique form of profound, forward-looking permanence.
The philosophical advantages of embracing semi-eternity extend beyond merely resolving the paradoxes of an infinite past. It offers a more natural framework for understanding the nature of abstract objects and laws within a temporal universe. Let’s take a look at the laws of physics. Did the law of gravity exist before the Big Bang? In a universe with a finite past, the answer seems plausibly negative. The laws, one might argue, came into being with the universe they govern. Yet, once established, they exhibit a constancy that appears absolute, persisting unchanged (as far as we can tell) throughout the universe’s entire history and projecting indefinitely into its future. They are, in this view, semi-eternal: born with the cosmos, destined to endure as long as the cosmos does, perhaps infinitely. Similarly, mathematical truths, the relationship of a circle’s circumference to its diameter, the infinitude of prime numbers, while often considered timeless or Platonic ideals, can be conceived within a temporal framework as discoveries. The truth they represent may be necessary, but its recognition by conscious beings occurs at a finite point in time. Once grasped, however, the truth persists as a fixed point of intellectual reference for all future time. Its validity is not contingent on future events; it is a future-infinite truth, established at a moment *t* (the moment of its discovery or the establishment of the logical framework that reveals it) and enduring without end.
Objections, naturally, arise. The most persistent challenges the very possibility of something becoming eternal. If an entity begins, critics argue, it belongs to the category of the contingent, the caused, the mutable. How can such an entity transition into a state of necessary, endless existence? Doesn’t its origin imply the potential for cessation? This objection hinges on a conflation of logical categories with temporal ones. Semi-eternity does not claim that the entity becomes logically necessary or immutable in the classical sense after its origin. It claims only that, as a matter of contingent fact, it will never cease to exist. Its endurance is a brute fact about its nature or the nature of the reality it inhabits, not a deduction from pure logic. We readily accept that fundamental particles or conservation laws simply are persistent features of our universe, without demanding a logical proof of their necessity from first principles. Their persistence is an observed, fundamental aspect of physical reality. Semi-eternity extends this notion of fundamental persistence indefinitely into the future. The entity’s origin does not logically preclude its endless endurance; it merely marks the point at which its existence commences. Its subsequent permanence is a separate property.
A related concern probes the cause of such an entity. If it began, what brought it about? And does not this cause itself demand explanation, potentially regressing infinitely or terminating in an uncaused cause (which then looks suspiciously like the classical eternal)? This is the domain of cosmological arguments, ancient and modern. The proponent of semi-eternity need not deny the principle of causation nor the possibility of a first cause. Indeed, the model is entirely compatible with the existence of a prime mover or initial creative act occurring at the finite origin point *t*. The key distinction is that this first cause itself could, in principle, be conceived as semi-eternal. Perhaps the quantum vacuum or the fundamental laws from which our universe emerged, existed for a finite duration before spawning our cosmos and will persist thereafter. Or perhaps the first cause was a timeless entity (classically eternal) that acted finitely in the past to create a semi-eternal universe. The semi-eternal model primarily concerns the nature of the enduring entity itself, not necessarily the ultimate explanation for its origin. It shows that the product of causation can coherently possess an infinite future duration without needing an infinite past, regardless of the nature of its cause. The cause might be classical eternal, semi-eternal or even have a different temporal status altogether; the semi-eternity of the effect remains logically intact.
The implications resonate beyond cosmology and metaphysics, touching upon existential and even theological considerations. The human fascination with immortality, the dream of enduring beyond the frail confines of the biological organism, often imagines a future-infinite existence. Whether conceived as an immortal soul persisting after bodily death or a future technological transcendence uploading consciousness into perpetual substrates, the vision is rarely one of having always existed. It is quintessentially a dream of beginning (in this mortal life) and then never ending. It is a vision of personal semi-eternity. Even conceptions of divinity can be reimagined. Process theology, for instance, often presents a God who is co-evolutionary with the universe, experiencing temporal succession and perhaps even having an origin (or at least a temporal aspect that began), while still being everlasting into the future. This divine figure, while perhaps lacking the rigid, immutable perfection of the Aristotelian prime mover, offers a vision of deity engaged in the unfolding of time, whose endless future is a promise rather than a static given. The psychological comfort or existential dread associated with eternity often hinges precisely on this sense of having become and now persisting, rather than a static, all-encompassing ‘always’.
The semi-eternal perspective underscores the profound asymmetry of time. Physics struggles with the arrow of time, the evident directionality from past to future marked by increasing entropy. Semi-eternity aligns with this asymmetry. The past is fixed, finite and unalterable; the future is open, potentially infinite and the domain of possibility and persistence. An entity that begins and then endures forever embodies this asymmetry: its origin is a singular, fixed point in the past; its future is an endless, unfolding horizon. Classical bidirectional eternity, especially in its timeless form, struggles to accommodate this fundamental directional flow that characterizes our experience of reality. Semi-eternity embraces it, finding the potential for genuine permanence in an unending continuation within the irreversible stream of time itself.
To insist that true eternity requires infinite existence in both temporal directions is to impose a symmetrical ideal onto a manifestly asymmetrical reality. It privileges a specific, historically contingent metaphysical definition over conceptual coherence and empirical compatibility. The notion of semi-eternity liberates the concept of endless persistence from the problematic requirement of “beginninglessness”. It provides a robust, paradox-free framework for understanding entities, from our potentially heat-death-bound universe to the immutable truths of mathematics, from the laws of physics to the enduring consequences of historical events, that come into being at a definite point and then persist, unchanging or evolving, for all future time. Their existence is not less profound, less permanent or less ‘eternal’ in a meaningful sense of endless endurance, because they had an origin. Their finitude in the past is a testament to emergence; their infinity in the future is the mark of their enduring significance within the unfolding fabric of time. They exist in the mode of the partial eternity: anchored by a finite origin, stretching towards an unbounded future, defining their permanence by the absolute refusal of an end. In this forward-only infinity, we find a model of permanence that is, perhaps, more resonant with the contingent, emergent and time-bound nature of the reality we inhabit, a permanence that begins.