Lee asked:
Hello! I was wondering if there is any relationship between personal identity and Nietzsche’s ideas of eternal recurrence. I know that time and personal identity are two concepts that are constantly interwoven, but I wonder if there is a way to think of eternal recurrence in this frame as well. Thanks!
Answer by Geoffrey Klempner
The best way I can answer your question, Lee, is to tell you a story:
Born in 1846, in Frankfurt, just two years after Friedrich Nietzsche, Karl Schmidt was the son of a prominent banker. It is known that he wrote one philosophical work, whose title has been sadly forgotten. He gave up philosophy and joined the family business after the one and only manuscript was destroyed in a fire at his publishing house before the book went into print.
Friends commented that Karl appeared to show little concern for his tragic loss. ‘I feel no less sorry for all the other Karls than I do for myself,’ he is reported to have said. It was only years later after his death that a notebook was discovered, in which Schmidt described his theory of ‘Endless Duplication.’
According to Schmidt’s theory, the universe is one of an infinite series of identical universes, existing side by side in space. ‘All the other Karls’ refers to the infinitely many Karl Schmidts.
“Be glad! You are not alone in your suffering, you are not alone in your joy. Every action that you do is done an infinite number of times, each time with the same result. If you hit the target once, you always hit the target and never miss. If you miss the target, then there is no point in regret because you miss the target every time.”
Commentators have noted that Schmidt’s theory bears a remarkable resemblance to Nietzsche’s theory of the Eternal Recurrence. However, the date of the notebook entry is five years before the first mention of the Eternal Recurrence in Nietzsche’s published works. Could it be that Nietzsche adapted Schmidt’s idea, applying his ‘endless duplication’ to a series of identical universes in time rather than in space?
Though the supposition is initially plausible, the problem is that there is no record that Nietzsche and Schmidt ever met. Also, it is also known that the Eternal Recurrence was first formulated by the Stoics two thousand years earlier. Maybe, like Nietzsche, Schmidt was intrigued by the Stoic theory, but for reasons of his own replaced the temporal series with a spatial one.
Although Nietzsche attempts a proof of the Eternal Recurrence in his notebooks posthumously published as The Will to Power, the point of the theory is a test, a thought experiment: are you mentally strong enough to will that in the infinite number of times that you will get the chance to relive your life, you will make the same decisions every time, and everything that happens in your life will be the same?
But will it be you? What makes the two Nietzsches, or the two Schmidts, the same person, rather than someone exactly like the previous Nietzsche, or the previous Schmidt?
In his book Theories of Existence (1985), Timothy Sprigge in a chapter on Nietzsche admits that the question about identity or non-identity in the Eternal Recurrence is one where there is no convincing proof either way, although he would ‘like to think’ that if the Eternal Recurrence is true then he, Timothy Sprigge, will live the same life, over and over again.
Maybe Schmidt considered the implications of this embarrassing loophole, and decided to improve on the Stoic theory by substituting space for time. In the next universe along in the spatial series of universes, there is no possibility that the GK typing these words at this moment is ‘one and the same’ as the GK in this universe.
Using Schmidt’s ‘endless duplication’, a stronger argument can be made, that there is no reason why the ‘next GK’ in the infinite temporal series of universes should bear any closer relation to the GK in this universe than the ‘next GK’ in the infinite spatial series of universes. If there are an infinite number of GKs in Schmidt’s Endless Duplication, then there must be an infinite number of GKs in Nietzsche’s Eternal Recurrence.
There is a counter-argument, however. Although Nietzsche doesn’t explicitly state this — and it appears inconsistent with the argument sketch in The Will to Power which assumes a deterministic Newtonian Universe in infinite time — an alternative interpretation of the Eternal Recurrence would be a circular time. Time is finite and circular rather than infinitely extended in a straight line. If time is circular, then the ‘next GK’ is none other than me because the universe has gone back to a previous time.
Just in case I get accused of promulgating ‘false facts’, the story about Karl Schmidt is made up. Any resemblance to any actual historical figure is purely coincidental. The original version of my story can be found here.
Ask a Philosopher 
Lee, you might also want to look at ‘Nietzsche and Philosophy’ by Gilles Deleuze. Here, Nietzsche’s doctrine of Eternal Return is used as a temporal structure which can either reinforce the existing domination of reactive drives that inform personal identity. Or, active drives can ‘break out’ of the reactive conformity at the same time and express themselves. Active drives may exist because of positive encounters with an other, other bodies and in affirming themselves, they can at the same time, change personal identity in varying degrees. In other words, the Will to Power of the active drives is qualitatively superior to the existing, conservative reactive drives.
Martin Jenkins.