"Eternal return" is the doctrine that every event in the universe, in all its details and in its whole cosmic context, will recur an infinite number of times in exactly the same way that it has already occurred an infinite number of times in the past. This doctrine must be distinguished from the belief in the general periodicity of nature, according to which the main features—but not the specific details—of human and cosmic history recur.
The periodicity of various phenomena is a fact of daily experience; the alternation of day and night, of lunar phases and of the seasons of the year, and the rhythm of breathing and heartbeats were known to primitive people. Even the idea that cosmic history repeats itself in its general features appeared in various forms in mythological thought. Among the pre-Socratics the idea was held by Anaximander, Empedocles, and the atomists. The existing universe was regarded as a result of the differentiation of an original chaos—watery, fiery, or qualitatively undetermined—into which it would eventually return and from which a similar universe would emerge. This idea of the periodicity of worlds soon became associated with the belief that not only the general features but also the most specific details would recur in the same order that they had occurred countless times in the past. According to Eudemus of Rhodes, this was the belief of the Pythagoreans: "Everything will eventually return in the self-same numerical order, and I shall converse with you staff in hand, and you will sit as you are sitting now, and so it will be in everything else, and it is reasonable to assume that time too will be the same" (H. Diels and W. Kranz, Fragmente der Vorsokratiker, 58B34).
The same idea of the cyclical nature of time was present, according to Pierre Duhem, in the thought of another Pythagorean, Archytas of Tarentum, who defined time as "the interval of the universe." The length of this cosmic cycle, called the Great Year or Perfect Number, was variously estimated by different thinkers who were influenced by Pythagoreanism. For Heraclitus it was equal to 10,800 years (according to another source 18,000 years). According to the testimony of the Stoics and of Simplicius (whose reliability on this point has been doubted by Friedrich Schleiermacher, Ferdinand Lassalle, John Burnet, and G. S. Kirk), it measured the period separating two successive conflagrations in which an old world perishes and a new one is reborn.
Plato and Aristotle
Plato associated the period of the Great Year not with a periodically recurring cataclysm but with a return of all the celestial bodies to the same relative positions. Nor did Aristotle accept a universal conflagration, which was clearly incompatible with his idea of the incorruptible celestial realm. Nevertheless he did, if we accept his authorship of the Problemata, uphold eternal return in its most radical form: "Just as the course of the firmament and each of the stars is a circle, why should not also the coming into being and the decay of perishable things be of such a kind that the same things again come into being and decay?" (The Works of Aristotle, Vol. VII, p. 916a). Aristotle realized that the circularity of becoming would imply a relativization of succession: If the Trojan War will inevitably recur, in a sense we are living "prior" to it. The author of Problemata, however, was reluctant to accept the ultimate consequence of the idea of cyclical becoming: "To demand that those who are coming into being should always be numerically identical, is foolish" (ibid.).
The problem of cyclical becoming was faced by the Stoics, who believed that at the end of each cosmic cycle a universal conflagration (•κπ•ρωσ•ις ) that dissolves the universe into the original fire will occur. This will coincide with the beginning of another cycle; the events of the previous cycle will then be reconstituted in all their details and in the same order. But Stoics followed Aristotle by claiming that another Socrates who will marry another Xantippe and be accused by another Meletus will not be numerically identical with the previous Socrates, since numerical identity implies an uninterrupted existence. Some younger Stoics, in conceding small differences between successive Socrateses, gave up the circularity of becoming in all but name.
A curious argument for eternal return was given by Plotinus in the Fifth Ennead (Book VII, Chs. 1, 2). According to Plotinus, the intelligible world contains the ideal patterns not only of genera but also of all individuals, each of which successively finds its embodiment in the realm of change. But since the supply of these patterns is finite, a time will come when the same pattern—for example, of Socrates—will have to be incarnated again, and this will be possible only in the next identical cosmic cycle. Thus the successive cycles are identical, but there is no repetition within each cycle.
Jewish and Early Christian Thought
Both Judaism and Christianity, with their emphasis on the finiteness and irreversibility of cosmic history, were strongly opposed to the doctrine of eternal return. According to both the Jewish and the Christian view, the history of the world is bounded by two unique and unrepeatable events: its beginning (the Creation) and end (the Last Judgment). Every individual human life is similarly unique.
Origen, while accepting with the Neoplatonists the eternity of the world and even metempsychosis, rejected the identity of successive cosmic cycles because such a concept was incompatible with human freedom. Nemesius (De Natura Hominis, Ch. 38) and St. Augustine (De Civitate Dei, Book XII, Chs. 11, 13) rejected the doctrine, Nemesius on the ground that the Resurrection cannot take place periodically, Augustine because the incarnation of Christ occurred only once.
A decree of 1277 threatening excommunication of those who accepted the Neoplatonic idea of a Great Year lasting thirty-six thousand years demonstrates the survival of this belief into the Middle Ages. Although St. Thomas Aquinas rejected the cyclical view of time by claiming that the re-creation of numerically identical individuals would be contradictory, and as such was beyond even God's power, his view was not shared by John Duns Scotus and William of Ockham. Nicolas Bonet and François de la Marche explicitly insisted on God's power to restore any past motion, and therefore a corresponding past interval of time, since there was no difference between motion and time.
Early Modern Thought
Thus, at the threshold of the modern era two of the central ideas of the modern cyclical view of time were present—the reversibility of motion and the relational theory of time. The third essential ingredient of the cyclical theory—the finiteness of the material universe—was excluded by Giordano Bruno's vision of innumerable worlds and limitless space. This may explain the absence of the idea of eternal recurrence in Bruno's contemporaries despite their Neoplatonic leanings. For if the number of constituent parts of the universe is infinite, the number of possible combinations is also infinite, and recurrence of the same configuration is not inevitable.
In Isaac Newton and his successors there was an additional motive for not considering the cyclical view. They regarded time as absolute, as intrinsically irreversible, irrespective of its content. Even a complete restoration of the content of the past moment would not make this moment itself present.
René Descartes came very close to the cyclical view when he wrote that matter must successively pass through all its possible forms, but since matter to him was coextensive with infinite space, the number of its configurations was inexhaustible. Furthermore, the pagan and astrological associations of the ancient cyclical theory made it thoroughly suspect.
Interest in eternal return was revived only with the development of modern cosmogony. The nebular hypothesis of Immanuel Kant (1755) and Pierre Simon de Laplace (1796) implicitly raised the question of the origin of any primordial nebula: Did it represent a truly initial stage preceded by an act of supernatural creation, or was it merely one of the countless stages in an unending cycle of successive worlds? The principle of the uniformity of nature in time, anticipated by Bruno's and Benedict (Baruch) de Spinoza's belief in the eternity of the universe, strongly favored the second answer. Although the law of entropy suggested the irreversibility of the whole cosmic process, because of its statistical character it did not exclude the general periodicity of nature. Various hypothetical mechanisms were invented to provide a "rewinding of the cosmic clock," at least on a local scale. The most popular one was that of cosmic clashes by which two stellar masses that had lost their heat could be transformed into another nebula, which would then develop into another world "ever the same in principle, but never the same in concrete results," as Herbert Spencer wrote in his First Principles (p. 550).
Such a new world could be the same even in concrete details only if the cosmic mass did not contain an infinite number of units. Eugen Dühring, in various writings (heavily annotated copies of which were found in Friedrich Nietzsche's library), rejected the concept of actual infinity as self-contradictory and inapplicable to the physical world.
In Nietzsche's thought the concept of a finite universe and of the discrete structure of matter implied a finite number of possible successive configurations, and therefore an inevitable recurrence of a configuration defining a state of the universe that had already occurred an infinite number of times in the past; and this recurring cosmic state must, according to the then accepted deterministic scheme, generate the series of the same events in the same order as in the previous cosmic cycles. This view, formulated by Nietzsche at the end of the fourth book of Fröhliche Wissenschaft (1881), became central to his philosophy. The intensely lyrical way in which this view was expressed in Thus Spake Zarathustra hid its intellectual origins, which are far more obvious in the posthumously published fragments of The Will to Power (see The Complete Works of Friedrich Nietzsche, Vol. XV, Ch. 2, esp. p. 430). Prior to Nietzsche only a few nineteenth-century thinkers held the same view: Louis A. Blanqui (Éternité par les astres, 1871), Gustave Le Bon (L'homme et les sociétés, 1881), Jean Marie Guyau (Vers d'un Philosophie, 1881). It was not held, however, by Dühring, who claimed that the continuity of space admitted an infinite number of configurations even if the number of atomic units was finite (Cursus der Philosophie, pp. 84–85). The same objection against eternal return was raised by Alois Riehl and Alfred Fouillée; against this view Franz Selety pointed out that concrete processes were discrete and not mathematically continuous, and therefore, he claimed, eternal recurrence was unavoidable; and G. N. Lewis claimed that the attempt at avoiding an exact recurrence by assuming a whole continuum of possible values is eliminated by the quantum theory.
Henri Poincaré, although he formulated the theorem of phases, according to which any mechanical system of a finite number of particles will in a sufficiently long time pass through a configuration infinitely close to the previous one, nevertheless dismissed the application of the theorem of phases to cosmogony in his Leçons sur les hypothèses cosmogoniques (p. 23) as "the dream of eternal return." C. S. Peirce (Collected Papers, Vol. I, pp. 498–500) held the cyclical view on the unusual ground that "since every portion of time is bounded by two instants, there must be a connection of time ringwise." Furthermore, this view was entirely incompatible with the rest of his philosophy. The arguments of Abel Rey in favor of the cyclical view were not essentially different from those of Nietzsche, since they were based on the classical corpuscular-kinetic scheme of nature.
The contemporary crisis of the classical scheme of nature makes the doctrine of eternal return extremely questionable. The doctrine was based on four fundamental assumptions: (a ) that the universe is made up of distinct atomic units that persist through time without any intrinsic change, so that they may be identified in successive moments; (b ) that the number of atomic units is finite; (c ) that it is meaningful to speak of a definite "state of the universe" at each instant; (d ) that one such particular state (embodied in a definite atomic configuration) causally determines all future states (Laplacean determinism).
Except for the thesis that the size of the universe is finite, which is favored by some cosmologists, none of these theses remains unchallenged by the recent developments in physics. The atoms of modern physics do not have the rigidity and permanence of classical atoms; and without permanent elements there can be no recurring configurations. The ontological status of "state of the universe at an instant" is challenged by the relativization of simultaneity, and the validity of rigorous determinism has been seriously questioned since the formulation of the indeterminacy principle in 1927.
Moreover, there are ambiguities and discrepancies within the theory of eternal return itself. The assumption of a completely identical repetition of cosmic situations makes the theory intrinsically unverifiable. Moreover, either the successive identical cycles are distinguished by their positions in time—which means that we surreptitiously introduce an irreversible time as their container—or we insist on the numerical identity of the cycles. But we then have only one cosmic cycle, and it clearly becomes meaningless to speak of a "succession of cycles" or of their "repetition." Although it is self-contradictory to speak of numerical identity of genuinely successive events, the two views have often been held jointly, as by the Scotists and Nietzsche.
The eternal return is rejected by all thinkers who insist on the irreversibility of becoming, genuine novelty, and the immortality of the past. Mircea Eliade regarded the theory as a manifestation of "ontology uncontaminated by time and becoming" (The Myth of the Eternal Return, p. 89); Émile Myerson saw in it an attempt to eliminate becoming (L'identité et réalité, Ch. 8). The emotional effect of the doctrine is equally ambiguous. Thus Nietzsche's mystical ecstasy over "the ring of eternity" was tinged by a note of anxiety and even despair. Gustave Le Bon compared the recurring cosmic cycles to the labors of Sisyphus, and Miguel de Unamuno, in The Tragic Sense of Life, regarded the doctrine as a poor substitute for personal immortality.
See also Anaximander; Aristotle; Atomism; Augustine, St.; Bruno, Giordano; Descartes, René; Dühring, Eugen Karl; Duns Scotus, John; Fouillée, Alfred; Heraclitus of Ephesus; Kant, Immanuel; Laplace, Pierre Simon de; Lassalle, Ferdinand; Nemesius of Emesa; Neoplatonism; Newton, Isaac; Nietzsche, Friedrich; Origen; Peirce, Charles Sanders; Plato; Plotinus; Poincaré, Jules Henri; Pre-Socratic Philosophy; Pythagoras and Pythagoreanism; Riehl, Alois; Schleiermacher, Friedrich Daniel Ernst; Simplicius; Spinoza, Benedict (Baruch) de; Stoicism; Unamuno y Jugo, Miguel de; William of Ockham.
classical and medieval
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nietzsche on eternal return
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Zawirski, Zygmunt. L'évolution de l'idée du temps. Cracow, 1936. Pp. 336ff.
Milič Čapek (1967)