Suppose someone claimed that since a given type of event has never been believed when it didn’t really happen, if it is believed then we have very strong evidence that the event really happened.

Is this claim valid?

It seems to me that for the lack of belief in an event of this type that didn’t actually happen to count as evidence that if belief in this type of event exists then the event must have happened, we need to be provided with an explanation which identified a resistance to belief in events of this type forming if the event didn’t actually happen. Without any identified resistance, we may suggest that in fact there is no special resistance to belief in events of this type forming if the event didn’t actually happen, and the reason why belief in events of this type didn’t form if the event didn’t actually happen is that the type of event is too narrowly defined to expect belief in an event of that type to have formed if the event didn’t really happen.

Is my reasoning above correct?

I am also unsure whether there is some alternative explanation we could give for why belief in events of this type didn’t form if the event didn’t actually happen (other than suggesting that the type of event is too narrowly defined to expect belief in an event of that type to have formed if the event didn't really happen). Can you think of some alternative explanations?

EDIT: I should have said that I am only considering events that could theoretically happen, not impossible events. Thank you @ScottRowe for pointing this out, and sorry for the confusion.

  • "Why, sometimes I have believed as many as six impossible things before breakfast." You are not trying hard enough.
    – Scott Rowe
    Apr 19 at 12:44
  • @ScottRowe Thanks for pointing that out, please see my edit. Apr 19 at 14:44
  • Assuming "has never been believed when it didn’t really happen" means p(¬B | ¬H) = 0, we get p(B ∧ H) = p(B) + P(H) - 1= P(H) - p(¬B) and p(H | B) = (p(H) - P(¬B))/p(B), so it depends on priors for the event happening and for it being believed. We may not need an explanation for the "resistance to belief", but we do need to know that it is high.
    – Conifold
    Apr 19 at 21:05

6 Answers 6


You're absolutely right. That claim about beliefs indicating something must have happened just because we haven't seen false beliefs of that type before? Yeah, that doesn't quite hold water without some more explanation. Look at it this way - just because I've never seen someone believe their dog could fly and start flapping their arms, that doesn't mean if my neighbor tells me their dog flew, I should automatically believe them! Maybe dogs just can't fly, so of course no one has that false belief.

For the "no false beliefs = it must be true" argument to work, we'd need to understand why false beliefs couldn't form in the first place. Like is there some rule of nature preventing it? Or is it just so darn specific that false beliefs are really unlikely? Without that context, the lack of false beliefs alone isn't strong evidence. It's a fair point you're making. If something seems unbelievable at face value, I need more than just "well no one's falsely believed it before!" to be fully convinced

Now, alternatives you are asking about

For one, it's possible the events in question are so mundane or ordinary that they just don't get much attention or discussion at all, true or not. Like if we're talking about beliefs that your neighbor took out the trash last Thursday - it's such an unremarkable thing that false beliefs likely wouldn't spread because no one cares enough to gossip about it.

Another possibility is that the events have pretty airtight verification processes or evidence requirements. So false beliefs can't gain traction because there's an expectation of proof. Like if we're talking UFO sightings, maybe the standards for what constitutes a "believable" claim are so stringent that vaporous stories get dismissed.

It could also be a culture or context thing. Maybe in certain communities or settings, there are really strong disincentives to spread misinformation or unfounded beliefs about this type of event specifically. So people apply extra scrutiny.

Or it's conceivable there was at one point a rash of false beliefs that caused such an uproar, it created a overcorrectional taboo against that ever happening again for this particular event type. Those are just some possibilities off the top of my head.

  • "really strong disincentives to spread misinformation" would be helpful right about now.
    – Scott Rowe
    Apr 19 at 12:49
  • @ScottRowe What do you mean? Apr 19 at 14:01

No, there is no necessary link between belief and fact. It is possible for a truth to be widely disbelieved and for there to be widespread belief in false claims. Not that long ago, it was commonly accepted that the Earth was flat, and a few people claiming otherwise were tortured as heretics. Now, suppose I genuinely believe the Earth was going to stop spinning on its axis tomorrow- something that had never been believed before and had never happened before- would you consider that to be strong evidence that my belief was correct?

  • Thanks for your answer Marco. The example you gave is an example where the belief is against a gigantic amount of definite evidence. Do you have any similar examples where the belief is not against a gigantic amount of definite evidence? Apr 19 at 13:49

No, the above claim is not valid.

  • Assume an event which cannot happen and assume that nobody until today correctly believed that the event will happen. But now people start to believe that it will happen the next day. Because the event is not possible by assumption, nevertheless the event cannot happen: Hence it will not happen.
  • The argument is simple: A belief does not change the facts.

For further discussion it would help to present some real example. Otherwise your thoughts hang in the air completely.

Added. After the OP made an edit and changed his/her assumption, my first bullet point does no longer apply. But I keep the second bullet point.

  • Thank you for your answer. I'm sorry for the lack of clarity: please see my edit. Apr 19 at 14:43

Any evidence that the event really happened is stationed on the cognitive impact of a subjective human experience, which is contingent on the neural processes arising out of sensory stimulus.The causal connection between subjective evidence and the event can never be dismissed. Further any evidence is limited to human intuition (analysed here.. The invisible gorilla experiment) Say, in the case of a Mirage, (where the critical angle of refraction , is inevitably surpassed by the construct of the eye, thereupon turns it out to be a reflection , failing the validity of perception)..For a dog that lacks rods and cones in its retina , the grass does not appear green ,although it's ears could be receptive to supersonic frequencies(galtons whistle), can hear sounds, deceptive to a human ,

An intrasigent attitude could open up several blind spots about any fact , that is deemed to be valid till another evidence sets a timeline for it

If an event is theoretically possible, a gnostic would belive the claim straight away , as against an agnostic who would reject it for lack of evidence. But one with scientific temperament would take the claim with a grain of salt, hypothesize ,seek evidence for a proof . Nevertheless absence of proof is never a proof of absence .It depends on the category of the observer, for not all observers are same


The argument is somewhat circular.

You start out with the premise "Nobody has ever believed X while X wasn't true".

But you also now, presumably, have someone who believes X. And you're using that to prove X is true...

...but if X ISN'T true, then the premise "Nobody has ever believed X while X wasn't true" is also not true.

In other words, you have to assume X is true in order to maintain the claim "Nobody has ever believed X while X wasn't true", which you then go on to use to support the claim that X is true.

  • I am not trying to prove anything. I am trying to find good evidence that X is true. I am considering a case where we don't know whether the X that someone believes in is true or not, and the claim that I am questioning the logic of uses the historical record to show that nobody has been known to believe in X while X is false. Apr 19 at 14:49
  • @A-LevelStudent is it also true in this situation that nobody has been known to believe in X whole X is true?
    – TKoL
    Apr 19 at 15:19
  • No, let's say that people have been known to believe in X while X is true. Does it make a difference? Apr 19 at 15:36
  • Maybe a little bit, yeah, that's useful information that you didn't include in your question @A-LevelStudent
    – TKoL
    Apr 19 at 16:11

You would need an additional premise to complete this argument:

  • belief by A in X is very unlikely unless X is true

If that premise is established, then A believing X would be some proxy evidence for the truth of X. The strength of the evidence would depend on how sure you are in the premise, exactly how unlikely it was that A would believe X if I were not true, and other circumstances that might explain a false belief other than the truth of X.

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