Philosophy Compass 7/3 (2012): 208–217, 10.1111/j.1747-9991.2011.00473.x Time and Personal Identity in Nietzsche’s Theory of Eternal Recurrence Scott Jenkins* University of Kansas Abstract Friedrich Nietzsche’s theory of eternal recurrence is an essential part of his mature philosophy, but the theory’s metaphysical commitments and practical implications are both obscure. In this essay I consider only the metaphysical elements of the theory, with the aim of determining whether it is possible that we live our lives infinitely many times, as the theory maintains. I argue that the pos- sibility of eternal recurrence turns on issues in personal identity and the metaphysics of time. As I proceed, I also consider the relation between Nietzsche’s theory of eternal recurrence and theories of recurrence found in the work of Heraclitus, the Pythagoreans, and the Stoics. Friedrich Nietzsche’s infamous doctrine of eternal recurrence receives its clearest expres- sion in The Gay Science. The heaviest weight. – What if some day or night a demon were to steal into your loneliest lone- liness and say to you: ‘This life as you now live it and have lived it you will have to live once again and innumerable times again; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unspeakably small or great in your life must return to you, all in the same succession and sequence—even this spider and this moon- light between the trees, and even this moment and I myself. The eternal hourglass of existence is turned over again and again, and you with it, speck of dust!’ Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experi- enced a tremendous moment when you would have answered him: ‘You are a god, and never have I heard anything more divine.’ If this thought gained power over you, as you are it would transform and possibly crush you; the question in each and every thing, ‘Do you want this again and innumerable times again?’ would lie on your actions as the heaviest weight! Or how well disposed would you have to become to yourself and to life to long for nothing more fervently than for this ultimate eternal confirmation and seal? (GS 341)1 According to the theory of eternal recurrence sketched by Nietzsche’s demon, the world consists of a single series of events that is repeated infinitely many times. Because your life is a part of this series, the theory maintains, you will live your life infinitely many times. Most of the questions to be asked concerning this passage can be sorted into three gen- eral categories. First, there are straightforwardly exegetical questions. We might wonder why the doctrine of eternal recurrence is introduced by a ‘‘demon,’’ why the passage addresses the reader directly, and why there is talk of moonlight, spiders, sighs, and so on. Second, there are questions concerning the practical significance of eternal recur- rence. Nietzsche says that eternal recurrence would be ‘‘the heaviest weight,’’ and he describes just two reactions to the doctrine – either crushing anguish or a longing for recurrence. We find the same pair of reactions in Thus Spoke Zarathustra, in which Zara- thustra is initially overpowered by an ‘‘abysmal thought’’ closely related to eternal recur- rence (Z III:13) but later comes to love this vision of eternity (Z III:16). Since these ª 2012 The Author Philosophy Compass ª 2012 Blackwell Publishing Ltd Nietzsche’s Theory of Eternal Recurrence 209 reactions probably do not fit your own, we might ask about Nietzsche’s reasons for thinking that eternal recurrence has this practical importance. Third, there are questions concerning the theory of eternal recurrence itself. We might ask what exactly the theory maintains about the world, what evidence or argument Nietzsche offers in support of the theory, and whether it is even possibly true that we will live our lives infinitely many times. I will focus on the third set of questions, which have recently returned to the forefront of Nietzsche scholarship thanks to studies by Paul Loeb (2010) and Robin Small (2010). My aim will be to locate Nietzsche’s theory of eternal recurrence within ancient discus- sions of cosmological recurrence, to determine whether Nietzsche’s theory could be true, and to outline what must be the case if it is to be true. As we will see, the possibility of eternal recurrence turns on issues in personal identity and the metaphysics of time. These issues are of historical and philosophical interest even if it turns out that the practical significance of eternal recurrence does not depend upon the truth or coherence of the theory.2 1. Recurrence Cosmology Today the idea of eternal recurrence is closely identified with Nietzsche’s writings, but the idea has a long history that Nietzsche knew well from his training in classics. In Ecce Homo Nietzsche identifies eternal recurrence with the doctrine of ‘‘the unconditional and infinitely repeated circular course of all things’’ and maintains that the doctrine ‘‘may have been taught already by Heraclitus’’ (EH BT:3). This remark connects eternal recur- rence with Heraclitus’ view that the world ‘‘always was and is and will be,’’ and that it changes states in ‘‘measures’’ (Fr. 30, Barnes 1979 1:61). The measured stages of the world occur through an inner necessity, forming an infinitely repeated cycle that Heracli- tus is thought to have regarded as a ‘‘great year’’ (see Kahn 156). These notions appear often in Nietzsche’s work. The animals that accompany Zarathustra attribute to him the thought that ‘‘there is a great year of becoming, a monster of a great year, which must, like an hourglass, turn over and over again […] and all these years are alike in what is greatest and what is smallest’’ (Z III:13). Nietzsche himself speaks of the world as a ‘‘musical mechanism [that] repeats eternally its tune, which must never be called a mel- ody’’ (GS 109). This denial that the series of events resembles a pleasing melody echoes Heraclitus’ claim that the necessary structure of existence is not produced by a god or by humanity (Fr. 30, Barnes 1979: 1:61). Nietzsche’s talk of renouncing a desire for an ‘‘ulti- mate peace’’ and willing the ‘‘eternal recurrence of war and peace’’ (GS 285) also recalls Heraclitus’ view of war as common to all things (Fr. 80, Barnes 1979: 1:60). It would be a mistake, though, to regard Heraclitus as the only ancient source of eternal recurrence. Empedocles, one of Nietzsche’s favorite ancient philosophers, also postulated the exis- tence of cosmic cycles (Barnes 1979: 2:6–8). In an early work Nietzsche also mentions the Pythagorean doctrine of cosmological recurrence (HL §2), and he later acknowledges the importance of recurrence within Stoic physics (EH BT:3). Nietzsche’s demon asserts the theory of eternal recurrence independent of evidence or argument. But unless Nietzsche means to establish its truth through appeal to the author- ity of his ancient predecessors, he must provide us with some evidence or argument in support of the theory. Arthur Danto has influentially maintained that there could be no empirical evidence of recurrence because the act of discovering such evidence would dis- tinguish this cycle of existence from other cycles, contrary to the theory’s claim that the infinitely many cycles are indistinguishable (Danto 204). Paul Loeb has recently shown ª 2012 The Author Philosophy Compass 7/3 (2012): 208–217, 10.1111/j.1747-9991.2011.00473.x Philosophy Compass ª 2012 Blackwell Publishing Ltd 210 Nietzsche’s Theory of Eternal Recurrence that this view is mistaken because the act of discovering evidence could, in principle, occur in every cycle (Loeb 17–8).3 Loeb claims, in addition, that individual experiences can serve as evidence of recurrence. Suppose a demon whispers the recurrence doctrine in your ear, or you suddenly have the overwhelming feeling that all of this has happened before. Such experiences, Loeb argues, would be evidence of multiple cycles of existence. Even if Loeb is right about this (I return to this point in Section 3), it is still not clear that such experiences could ever justify belief in recurrence. People often hear voices or experience de´ja` vu, but even the most intense, emotionally resonant experiences of this sort would provide an insecure foundation for a theory of the cosmos. If individual experiences are not sufficient to establish cosmological recurrence, a scien- tific or metaphysical demonstration of recurrence would be necessary. Zarathustra does provide a proof of sorts (Z III:2.2), and Nietzsche’s notebooks contain multiple sketches of proofs. Nietzsche’s best-known argument, perhaps inspired by the Stoics, aims to derive recurrence from the unboundedness of time and the finitude of energy and possi- ble energy states. Stated succinctly, ‘‘the principle of the conservation of energy demands eternal recurrence’’ (Nietzsche 2003: 112). Much has been written about Nietzsche’s proofs, and there is no consensus concerning the best formulation of the arguments, or concern- ing their philosophical merits (see Capek; van Fraassen 1962; Moles; Rogers; Soll; Whit- lock). Even if Nietzsche’s proofs are unsound, it seems possible for the cosmos to be ordered as Nietzsche and his predecessors maintain. For the sake of examining whether the theory of eternal recurrence could be true, I will assume that the cosmos consists of a single ‘‘great year’’ of events. 2. Personal Identity and Circular Time Even if this cosmological theory is true, it does not obviously follow that persons will live their lives again, as Nietzsche’s theory of eternal recurrence maintains.