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The Impossibility of Knowledge of Retrocognitive Knowledge

Is it possible to prove the existence of retrocognition if precognition also exists, because precognition could be used to foresee any proof found of retrocognition? Does this also disprove precognition as well?

A curious argument (Sabine1950) claims to disprove the opposite of ‘precognition’, ‘retrocognition’:

Because any proven case of retrocognition could actually be a case of precognition of the proof, we can either prove the existence of precognition or retrocognition; and because precognition has been scientifically proven (Sabine & others believe), therefore retrocognition is unprovable; and since one should not believe in the unprovable, retrocognition is false.

This argument resembles skeptical arguments in epistemology, and may be applicable to precognition itself.

Sabine discusses cases of retrocognition, ending with the Moberly-Jourdain incident, in which a pair of English lesbians got lost touring Versailles & believed they had engaged in retrocognition of a day in Queen Marie Antoinette’s pre-Revolution life, and supposedly verified their historical observations of then-disused clothing & architecture by their later archival research revealing things they couldn’t’ve known then but saw in the incident.

Moberly-Jourdain Criticisms

The Moberly-Jourdain incident has many standard skeptical criticisms focusing on: problems in their timeline of documenting the incident & how the incident grew in the telling and may have incorporated the archival research or greater prior knowledge than admitted; the malleability of memory & the apparent folie à deux; their other paranormal experiences; the consistency of then-contemporary Versailles’s layout with their narrative; and even, curiously, the popularity of costume parties in Versailles (particularly by several French Decadents who would cross-dress as Marie Antoinette). Most people, including parapsychologists reviewing the Moberly-Jourdain book, find these adequate.

Kripkenstein The Psychic

Sabine, however, adds a much more interesting criticism than any of those mundane points. Sabine points out that the verifications “did not contain any information not ascribable to clairvoyant awareness of documents and books, and/or precognition of the coming experience of looking them up.” (emphasis added) And Sabine (himself a believer in precognition) concludes:

…It is evident that the difficulty which confronts us in the case of apparent retrocognition is similar to and even greater than that presented by apparent spirit communications. Precisely what information of the past could we accept as satisfactory?

If we were told that a retrocognitive vision revealed that the crew of the Marie Celeste had been carried off by pirates and murdered, how should we know whether it was true? And if we arrived at proofs as a result of the vision, could it not be said that those proofs had already been discovered by extrasensory perception which then manifested itself in the form of the vision? Again, if some lost art of manufacture were recovered, or if some mysterious hieroglyphics were explained by seeming retrocognition, it might be held that the explanation would rather be found in extrasensory awareness of the minds of living persons who had been engrossed by the problems in question, and whose unconscious minds had arrived at the solutions.

These difficulties serve to reinforce the need to consider anew whether there is a prima-facie case for retrocognition. It was propounded as a supposed necessary corollary of the existence of precognition. But, as indicated above, the necessity depends upon the view taken of the nature of precognition.

Since the present writer believes that the real nature of precognition gives no support to the view that it arises from perception of a physical future event existing at the time of the precognition, he is bound to conclude that the place assigned to the corresponding theory of retrocognition is already occupied by the individual memory.

It is a skeptical attack on verification anticipating Wittgenstein on Rules and Private Language/memory skepticism (cf. Boltzmann brain, Omphalos): to prove precognition, the ‘precog’ provides knowledge of future events which could not be known at the time of prediction, which then is later verified. Likewise, to prove retrocognition empirically, one presumably would show that the ‘retrocog’ provided knowledge impossible to know at that time, which was then later verified (such as from future archaeological expeditions1). Any knowledge which was already known would be no proof, because the retrocog could have obtained it in some way, such as fraud or forgetfulness, or even ‘just’ telepathy/clairvoyance.

However, future verification doesn’t work either: because the supposed retrocog could in fact be a precog who has foreseen the future verification itself! No matter what public verification there is of the retrocog’s claims, the precog could pass it equally easily by simply snooping on the future, where someone must have obtained the knowledge to be verified.

Thus, a retrocog might be able to prove the existence of retrocognition to themselves, given their privileged access to their own mind, but they cannot prove retrocognition to anyone else—unless precognition has already been disproven. So one can have proof of either precognition or retrocognition, but not both.

Attempts to subvert this by trickery like zero-knowledge proofs on cryptographic machines, to avoid a human ever knowing the knowledge, fail since, without hard known constraints on what precognition can do, the precog might be able to snoop on the internals, or just brute-force the ‘right’ prediction until they have a stable time-loop2 (see Moravec1991).


Rhine19743 points out that telepathy/clairvoyance is also vulnerable to a similar epistemic collapse into precognition: any knowledge gained of the contemporary world could just be knowledge of the future just a Planck-second away or knowledge of the future verification.

Retrocognitive Reversal?

Meanwhile, retrocogs appear to have no similar ability to fake precognition.

If an experiment is designed such that the randomized result is recorded before the retrocog makes their ‘prediction’, then they can cheat; but it would be easy to simply elicit predictions before randomizing. One could imagine retrocognition accompanied by a Laplacian demon-like ability to extrapolate a deterministic universe, in which case retrocognition could be used to acquire all necessary knowledge (like the locations & velocities of every molecule in the room 1 Planck-second ago) to extrapolate out the result of randomizing, and thus ‘predict’ it; but while there is no way to rule out such cosmic abilities (if we’re going to postulate psi abilities to begin with), it doesn’t seem too plausible or interesting. A third approach would be to exploit selection effects & testability: a retrocog could examine the past of the experimenters, and take actions in the present to avoid stringent tests before the experimenters themselves know that they were going to test precognitive powers; the ‘precog’ simply never shows up where a sufficiently stringent experiment would have been run, and only shows up for the ones they can cheat. However, at some point, this would become obvious, if only from the statistics, and isn’t great either.

These possibilities all trade-off to some degree—the more the experiment results can be ‘read off’ the present, the less need to dodge stringent experiments and the less demonic power required to extrapolate (eg. if one knows the current state of a deck of cards, then one can make above-chance predictions of the result of even several shuffles, as card cheaters have long exploited the fact that card shuffling is far from a perfect source of randomness), and vice-versa. So a retrocog could plead weakness of precognitive abilities and fake some limited precognition based on how well they can combine all the cheating methods, but they do not get anything as good as the skeptical attack.

Why not? There seems to be a causal asymmetry here in that precogs can ‘change the past’ by simply acting in the present (enabling stable time loops-as well) and so can cope with any possible future, while retrocogs are presented with a fixed past that it is now too late to alter and may already have beaten them.

Proving Too Much

Indeed, precogs are so powerful that this line of thought may ironically ‘prove too much’ & refute precognition as well. I suggest Sabine’s retrocognition attack lends itself to a similar skeptical attack on precognition agnosticism, similar to the classic Fermi paradox-style disproof of unrestricted time travel: “if time travel were possible to invent, they would already have traveled to the past and revealed themselves / invented time travel technology”.

If precognition is ever proven in the future, precogs could tell us the proof in the present (in the same way ‘retrocogs’ may be doing for retrocognition). They have not4, so precognition must not ever be proven. Further, regardless of how hard proving precognition is and how unlikely it is that it would happen on its own, they could set up a stable time-loop amplifying even epsilon probability to 100% probability. But then why is precognition so hard to prove, so subtle and elusive, so discouraged by ‘goats’ (unbelievers), so often disappearing as experiments become more rigorous? This also potentially applies to any proof of precognition by anyone ever: that proof could have been snooped by precognition and presented already, and has not been, so it will never exist. So, unless we already believe precognition proven, then precognition must not be provable at all, in any circumstance; and if its existence cannot be proven, there is no good reason to think it exists, and it is disproven.

On the other hand, if we attempt to save precognition agnosticism by asserting that precogs are too limited to foresee the future verification of their precognition, then the argument against retrocognition collapses as well: the ‘retrocog’ precogs are equally unable to foresee verifications of precognition.

So precognition of verification offers a trilemma: argue that precognition is already proven, that it has been disproven by not yet being proven, or that precognition is too weak to prove itself (and thus disprove retrocognition). While Sabine might have been comfortable asserting in 1950 that precognition was already proven, given the subsequent history of parapsychology research, this trilemma would probably be much more uncomfortable for Sabine today.

  1. A similar epistemological issue exists for deciphering language (cf. ‘problem of old evidence’): if one claims to have deciphered Linear B or used fancy X-ray & machine learning technology to ‘read’ the Herculaneum scrolls, how does one prove that? (Consider the many false solutions of Egyptian hieroglyphics by everyone from Athanasius Kircher to Joseph Smith.)

    If the recovered text is completely novel, then by definition, one has no way to test it; and if it is the translation of an already-known text (eg. the Rosetta stone), then the ‘translator’ could simply be copying from that! So, tests tend to rely on ‘new’ text or artifacts—where it would be astronomically unlikely to decode to something meaningful if the proposed methods were confabulations or overfit. And there may, unfortunately, never be any such new evidence.↩︎

  2. One is reminded of Dune Messiah, where protagonist Paul Atreides is blinded, but continues to act as if he is perfectly sighted, because he is able to use his precognitive abilities to simply foresee what is around him in the next instant!

    The catch is that his ability to substitute precognition for eyesight depends on him enacting the precognitive vision and making it all come true. Once he breaks from the pre-set path, his ‘vision’ will disappear and he will go permanently blind.↩︎

  3. WP, incidentally, attributes this skeptical argument against retrocognition to a 1977 history of parapsychology by J. B. Rhine (in Handbook of Parapsychology), but Rhine’s discussion is cursory & includes no citations, so his argument may come from Sabine.↩︎

  4. This is where Sabine would differ, saying that precognition has in fact been proven and so there is no problem—whether precogs really see the future events or just the verification thereof, either way that proves precognition exists.

    So this anti-precognitive skeptical attack is more relevant to the precognitive agnostic, who thinks precognition has been neither proven nor disproven.↩︎

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