If someone clearly believes that he has witnessed something extraordinary very clearly, why is it more reasonable to believe that they hallucinated?

Question

I'd first like to make the following point: there is definitely a point at which evidence does make it reasonable to believe extraordinary claims. For example, if all of Europe claims to have seen the stars spell out a clear sentence for the past 5 nights, we should believe that the stars did spell out a clear sentence for the past 5 nights over Europe, despite the extraordinary nature of this claim.

Now, consider the following scenario.

Person A clearly believes that he has witnessed an extraordinary event in such a way that we are faced with only two possibilities: either he really did witness the extraordinary event, or he hallucinated. The extraordinary event is something which we have no evidence against or evidence in favour of other than A's claim.

For example, imagine that someone bolts out of the Amazon rainforest, very clearly terrified, claiming to have seen a monster very clearly for some time (a time that hallucinations can certainly often last for). His description makes it clear that we would not have expected to have discovered this monster if it really did exist. (Perhaps he describes it as able to materialise and dematerialise at will, extremely fast and vicious, so it's usually very hard to see or escape from if seen and it doesn't leave tracks.) This means that there is no evidence against the existence of this monster, and there is no evidence in favour of the existence of this monster prior to this person's claim.

I think that it's clear that we should believe that the person hallucinated.

However, why should believe that the person hallucinated? The probability that a given sight is a hallucination is surely something like 1 in 1,000,000. Why do we choose to believe something so improbable instead of believing the man's claim?

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I have the following suggestion to answer my question above, but I'm not sure if it's correct, for a reason that I will adduce at the end of this section.

It is true that the probability that a particular sight is due to a hallucination is something like 1 in 1,000,000. However, the probability that someone will hallucinate on a randomly chosen day is assumedly quite high. The fact that this second possibility is quite high makes the proposition that this person hallucinated more reasonable to believe. (I admit that I haven't explained why the second probability being high has this effect. At the moment I can't explain it clearly.)

This reasoning is apparently very similar to the reasoning we use to see why it's reasonable to believe that the particular person who won the lottery won it fairly. One might have said the following: "The probability of a particular person will fairly win the lottery is about 1 in 14,000,000. That is a tiny probability. Therefore, it is more reasonable to believe that the particular person who won the lottery won it unfairly." Using the paragraph above, we may explain why this is incorrect. It is true that it is very unlikely that a particular person will win the lottery fairly, but it is almost certain that someone will win the lottery fairly if nobody interferes.

What makes me unsure about my reasoning is the following. Imagine that a mass extinction event had previously occurred, and that person A and the person who hears A's claim are the only humans left alive in the universe. In this case, the probability that someone will hallucinate on a randomly chosen day becomes extremely small due to the tiny remaining human population. If so, according to my reasoning above, it would become more reasonable to believe that A saw what he claims to have seen than to believe that he hallucinated. This might be correct, but I am not sure.

Is my suggestion correct?

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EDIT

I am just adding this edit to clarify and emphasise a few points and to avoid confusion and misinterpretation.

• In my Europe case, I specifically say that the case I am making up is when all of Europe actually claims to have seen the stars spell out a clear message.
• The scenario that my question is about is only when the person 'clearly believes that he has witnessed an extraordinary event'. (This precludes the possibility that the person is lying.)
• The scenario that my question is about is only when 'we are faced with only two possibilities: either he really did witness the extraordinary event, or he hallucinated'. (This precludes the possibility that anything else is responsible for his belief that he witnessed the event.)
• The scenario that my question is about is only when the 'extraordinary event is something which we have no evidence against or evidence in favour of other than A's claim'. (This precludes scenarios where we would have expected to be aware of what A claims to have seen if it really existed, for example.)
• I did not say that the probability that a person will hallucinate is roughly 1 in 1,000,000. I said that the probability that a given sight is a hallucination is roughly 1,000,000.
• In the lottery case that I mention, I am specifically talking about 'the particular person who won the lottery'. I am not talking about someone claiming that he won the lottery with no evidence to his claim.
• The mass extinction event that I mention is nothing to do with the essence of the story I talk about. I only intended to provide a quick explanation for why in my story there are only 2 people left alive in the universe. If it's confusing, please ignore it: the point is that in my story, there are only 2 people left alive in the world.

Apologies if I didn't make these points clear enough in my question.

Answer 1

Note that there are two relevant questions:

• Did they really have the sensory experience they're claiming to have had?
• What is the best explanation for the sensory experience they had?

For the first point:

• They may have just consciously made it up (i.e. they are lying). We tend to grant that people aren't lying, but certainly some people lie.
• This point also includes faulty memory, i.e. people misremembering what happened - we have strong evidence that people can misremember significant details and that this can happen on large scale.
• People could also poorly describe the experience they remember (regardless of whether that memory is correct). I remember that as a young child, I once told my mom that I "saw faces" (which weren't there), which made her quite concerned. But in reality, I was just seeing some spots in my vision, which I called faces for some reason. I might suppose that adults would more accurately describe their remembered experience, but I've heard plenty of accounts where people's initial summary sounds a lot more impressive than what they say when you dig into specifics.

But I'll focus on hallucination (the second point).

They may claim that their sensory experience is best explained by some deity, for example, but just because they have some explanation doesn't mean that explanation is correct. We can evaluate the sensory experience they describe and draw our own conclusions about what best explains that data: is it due to the deity they claim, is it due to some other entity or natural phenomenon, is it just a product of their mind (hallucination), or is it some combination of factors.

Let's say 1 in a million people hallucinate. Based on that, that's about 8000 of the people on the planet. If someone's claiming something which e.g. violates the laws of nature as we know them and if true, should have far-reaching consequences which we don't see, it seems more reasonable to suppose they're one of those 8000 people instead. It is true that for a larger population, we'd expect more claims explained by hallucination. When evaluating a single claim, however, it's mostly just about the unreliability of eyewitness testimony thanks to the possibility of hallucination or other factors (like false memory, poor explanations or lies).

Although "hallucinate" tends to be a term people look down upon, seeing anyone who hallucinates as fundamentally living in their own world apart from the rest of us and not capable of being a functioning member of society. It is the case that frequent and severe hallucinations could make it difficult to function independently in society. But hallucinations exist on a spectrum - one might see a light and interpret that as some blurry angelic figure (perhaps a form of pareidolia), or one's mind might fabricate an entire vivid experience. Dreams could be said to be a form of hallucinations. I'd probably say that anyone has the capacity to hallucinate under certain circumstances (so not "1 in a million", but closer to "1 in 1").

We have a fairly good idea of when hallucinations happen, which I go into in my answer to Is the hallucination hypothesis always the best explanation?. But a lot of those factors may be difficult for a third-party to evaluate, and a big part of differentiating hallucination from reality would be evidence that extends beyond a singular person experience, such as shared experiences, repeated experiences or other lines of evidence such as recordings. I'd say my own singular person experience is a hallucination if it violates the laws of nature as we know them and I don't have other strong pieces of evidence that would lead to a better explanation than hallucination.

* You mentioned someone winning the lottery. If someone told me they won the lottery, I may tentatively accept that as true, because it is a thing that's known to happen. But I'd need a lot more evidence than them merely saying they won (such as signs of wealth) for me to rely on that being the case or if the truth of that would have significant consequences on my life.

Answer 2

If I'm understanding: at its core this is a question purely about probability, and could be expressed as something like:

• Someone rolls two 6s on a pair of dice. There was only a 1/36 chance of this occuring naturally with fair dice. Does that mean we should believe the roll was rigged?

You could reason that rolling two sixes is bound to happen occasionally with how many dice are being thrown every day - but then what if, like in your question, they're the only human on earth and are rolling the dice only once?

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Notation:

• P(A) = "The probability of A occurring"
• P(¬A) = "The probability of A not occurring"
• P(A|B) = "The probability of A occurring, given B"

As before, the probability of rolling two sixes given fair dice is 1/36: P(Sixes|Fair) = 1/36. The critical thing to note is that the complement of this, P(¬Sixes|Fair) = 35/36, is the probability of not rolling two sixes given fair dice. It isn't the probability that the dice are unfair.

Equivalently, you're considering a probability of 1 in 1000000 that someone sees something despite there being nothing: P(Perception|¬Monster) = 1/1000000. The complement of this, P(¬Perception|¬Monster) = 999999/1000000, is the probability that they didn't have any perception given no monster. It isn't the probability that there was a monster.

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To decide whether to believe in the monster, what we want to figure out is instead P(Monster|Perception) - the probability of the monster being real given the person's perception. Bayes' theorem tells us:

P(Monster|Perception) = P(Monster)P(Perception|Monster) / P(Perception)

• P(Monster) is our prior probability of this monster existing. Before hearing the claim we had no particular reason to believe in this specific monster, and out of all possible things practically none actually exist (particuarly of this reality-bending type, if we want to take that into account), so this would be extremely low - maybe 10^-15.

• P(Perception|Monster) is chance of this perception assuming that the monster is real. Lets say in a given timeframe (80 years) someone has a 10^-10 chance of a real perception (encountering this monster and living to tell the tale), plus a 10^-12 chance of a hallucinated perception (you can still hallucinate it despite it being real)

• P(Perception) is the chance of this perception regardless of whether or not the monster is real. We can calculate this by breaking it into the two cases and using what we've worked out so far:

  P(Perception) = P(Monster)P(Perception|Monster) + P(¬Monster)P(Perception|¬Monster)

  P(Perception) = 10^-15 * (10^-10 + 10^-12) + (1 - 10^-15) * 10^-12

  P(Perception) ~= 10^-12

Putting all that into Bayes' theorem:

P(Monster|Perception) ~= 10^-15 * (10^-10 + 10^-12) / 10^-12
P(Monster|Perception) ~= 10^-13

So, 100X more likely than it was when you had no evidence for this particular monster, but still overall very unlikely.

Numbers may vary significantly. The main takeaway would just be that "1/1000000 chance of perception, given no monster" does not imply "1/1000000 chance of no monster, given perception", in the same way "1/36 of this roll, given fair dice" does not imply "1/36 chance of fair dice, given this roll".

Answer 3

The probability that someone somewhere will experience a hallucination or any other perceptual anomaly (misperceiving depth, speed, or size; blind spots; other visual illusions) leading them to to have "seen a monster" or some such extraordinary event is high.

Depending on what the "extraordinary event" is, the probability of perceptual failure is normally much greater than the probability of one of the theories precluding the "extraordinary event" being false.

• If the "extraordinary event" is observing a small bird thought extinct since 1900, that is not terribly improbable.

• If the "extraordinary event" is the observation of a new species, similar to existing species, in a remote area, that is not terribly improbable.

• If the "extraordinary event" is observing a full size Tyrannosaurus rex, that is quite improbable, given the numbers of them that would have had to have gone unobserved until now.

• If the "extraordinary event" is having seen the moon explode and then return to its present shape, that is quite improbable, given the expected number of other people that would have seen it and instruments that would have recorded it.

• Etc.

Answer 4

This should probably depend on what the person has claimed to have seen and how many people have claimed to see it.

The OP gives an example of one person claiming to have seen a monster in the Amazon forest with no scientific evidence negating it's existence. There would however be other logical difficulty with such a story. Assuming a monster that can materialize and dematerialize exists why is it exclusively spending it's time in the Amazon forest? Why do no native tribes who live in the Amazon have legends about it? etc. Therefore the likelihood of it being a hallucination is far greater than the likelihood that he actually seen it.

There is no analogy to a lottery. By a lotter you already know for a fact there will be a one winner out of many millions. There is no reason to suspect that the winning was fraudulent because that materialized. There is also no analogy to a mass extinction event with two survivors. Mass extinction events do not happen in the order of the natural world. Were such unnatural events taking place it would be more reasonable to assume that other unnatural events took place too. Furthermore no, there is no guarantee that survivor "A" is accurate in his depiction of the events.

Getting back to the case of if all of Europe claims to have seen the stars spell out a clear sentence for the past 5 nights, we would believe it. In such a case the volume of anecdotal evidence would be too high and the evidence of the claim would be so overwhelmingly strong it would not be possible to rationally come to the conclusion that it wasn't true. Even were scientists to have claimed it was impossible

Answer 5

Religious books are filled with extraordinary claims. Big bang, evolution also makes extraordinary claims. We are living in a scientific age. We want evidence. Moreover , we want to take technology to its heights. If you wish to impress the scientific society then you must provide direct evidence otherwise your extraordinary claims would be likely considered hallucinations.

However if you go back few thousand years or if you live your religion ( which is unscientific ) devoutly then you will find more extraordinary happenings which will be acceptable in your society. Religious experiences can be very personal as well. You dont need to speak or share everything. Buddha for example discourages his followers to show “magic”(extraordinary happenings).

Answer 6

Yes, the core issue is that if we just want to take the word of anyone about something, we'd be forced to positively believe in thousands of things claimed by various people with mental issues, frauds, people with delusions, and so on. And those things we'd be forced to believe would be mutually contradictory and inconsistent.

So that would immediately lead to a rationally untenable set of beliefs. To keep a rational set of beliefs that are not strongly inconsistent, we need to either set the bar higher, or cherry pick which stories to believe based on what fits our beliefs without requiring stronger evidence for pleasing wild claims. Philosophy rejects the latter approach, theology endorses it.

As an example the Catholic Church has official guidelines on when to accept something as a miracle, and one of the criteria is that the report must fit with the churches teaching. So if some other god existed and made some real fancy magic trick, the church would just discard that no matter how many witnesses, if it could cast doubt on Jesus. That is irrational and unfair cherry-picking for the benefit of strengthening a cult.

Answer 7

I wouldn't know if this "answer" will satisfy all readers, but according to Laplace, given that you've made b observations and out of them a is the number of times a phenomenon in question (say the sun rising) has occurred, the probability that it will occur again p = (a + 1)/(b + 1). Just for the record, Laplace proved it. An ordinary event would have:
a ≈ b i.e. p ≈ 1.

So, an extraordinary event's occurrence would be 1 - p ≈ 0 and there's our ... hallucination.

Answer 8

What is the probability that unicorns exist? Surely if they existed we would have found one by now? But let's pretend it's a one in ten million chance they're out there somewhere.

If unicorns do exist, what is the probability that I will run into a unicorn next time I go exploring a rainforest? If they've evaded humanity for so long, they must be good at hiding. Given that nobody else who's been to this rainforest has claimed to see one, it seems unlikely they're there, and unlikely that I'd find one if they were there. Call it one in a million.

So now we're dealing with a one in ten trillion chance of me actually running into a unicorn.

What are the chances of me experiencing at least one hallucination while I'm in a rainforest? What are the chances of my hallucination being of a creature that is popular in pop culture and mythology? Neither of those seem that unlikely.

If we frame it as, "What are the chances of me experiencing a hallucination at any given moment?" then the odds go down. But equally, "What are the chances of me seeing a real unicorn at any given moment?" - this would also be unlikely, so now we're dealing with an event that is far less probable than one in ten trillion.

If I think I saw one, it's far more likely to have been a hallucination than a real animal. And if I claim I saw one, it's more likely still that I'm joking.

Answer 9

What you describe is essentially a (modern) religious experience: It is a profound subjective event indicating a presence which is not provable or disprovable. The latter is an element of modern religions (prehistoric religions often contained "provable" predictions, like eclipses).

In fact, your friend may indeed be so shaken by their experience that they start a religion or cult-like movement.

Therefore, the discussion of the veracity of religious experiences, which has a rich history, apply to your friend's experience as well.

Note that while your premise is that the monster does not leave detectable traces, such traces are, so to speak, an "ontological Turing test" for non-religious claims: Leaving no traces indicates, to a pragmatist, the monster's non-existence, the same way the absence of intelligent behavior indicates the absence of intelligence. (Searle would disagree, of course.) An actually existing monster would eventually be detectable.

Answer 10

Question:

"Why is it more reasonable to believe that they hallucinated?"

The problem with answering this question is hidden in this self-contradictory assumption:

"The extraordinary event is something which we have no evidence against or evidence in favour of other than A's claim."

Which leads us to ask:

• In which way is the event extraordinary if we have no evidence against it?!! Surely, if we have no evidence either for or against, there's nothing extraordinary about it happening.

However, the existence of a monster that is able to materialize and dematerialize at will is not something we have no evidence against. On the contrary, we have mountains of evidence in physics that this property is extremely unlikely.

Perhaps what you meant to say is that we have no empirical evidence about the existence of this particular monster, but that's definitely not the same as saying we have no evidence at all.

Given that, according to the laws of physics, it's much less likely that a monster can materialize and dematerialize at will, than that a person experiences such a halluciation, we should give more credence to the hallucination theroy.

Answer 11

***The probability that a given sight is a hallucination is surely something like 1 in 1,000,000

First of all, where did you get this number? In fact it's closer to 1 in 1. Everyone one or several times in life "sees" something that isn't in fact there. A simple case - you see a cat in the distance and come closer and booms! It was a plastic bag in the wind.

Basically this simple fact is enough to answer your question. But people also lie, have you heard of lies? Moreover they lie a lot.

And the last one - there is such a thing as difference between information and fact. I don't need to believe a person hallucinates, but until there is a serious proof and evidence I also don't have to take what he said as a fact. He just told me some information. "I saw an alien" - is information. It means a person told that he he saw an alien. It doesn't mean he saw an alien. It's very simple.

It also doesn't natter how sincere this person is. A person can absolutely believe he saw an alien. It's still just information. Give evidence.

Answer 12

Addressing only your criteria for an event for which there is no evidence for or against it having occurred:

I consider evidence requirements in a similar way to the way we consider message sizes in information theory. (They are, in fact, related!)

If you have a message about something that everyone already knows, you have 0 bits of information to impart. This is analogous to not having to prove a claim that everyone already agrees is true through prior experience. If you have something that is very similar to other people's experiences, you only need to communicate the portion that does not map to the shared information. In the same way, a claim about something that is not very unusual does not require much back-up evidence. The further your message is from shared information, the larger the message needs to be to specify what you are talking about. Similarly, the more unusual your claim, or the further it is from shared experience, the more evidence is required to back it up.

So, your monster example would be a message that is very different from shared information (no one else has experienced it) and has no supporting information that could convey the message. This would require a large message / a lot of evidence. The part that is missing is that contradictory information simply means that the message would require even more information to counter that information and then send the message. In the same way, a lack of contradictory evidence in no way supports a claim, it simply fails to hinder it.

"I experienced X" is simply not enough evidence for "X is true" in mundane circumstances (such as a legal case!), much less your created "monster" example.

Answer 13

Monsters materializing and dematerializing reminds me towards this Mahabharata story of quasi-real quasi-psychological demons.

Krishna and his elder wrestler brother Balram were walking through the forests when night fell. The silver moon filtered through the leaves and the wind blew with its might. They decided it was best to rest till the crack of the dawn. While one would sleep, the other would watch over for wild beasts; and they would take turns. Elder Balram insisted that Krishna rest and he would stand guard. Balram was smiling to himself as he watched the child Krishna sleep when he suddenly heard a sound, “Aaaaaa”.

Startled, he looked around and saw a demon about his height watching him with hungry eyes. Balram was scared and with a quiver in his voice, he asked, “Whhh..ooo aaa..rr..ee yooo..u?” The demon laughed and said, “I am a demon. And I am the size of your fear!” As he was saying this, he started growing bigger. Indeed, Balram was petrified. The more afraid he was, the more the demon kept growing. The more the demon grew, the more panicked Balram became. The demon was now towering – almost three times Balram’s size. Balram had reached breaking point.
“Krishnaaaaa!” he screamed and passed out.

Sleepily, Krishna woke up and saw Balram lying next to him. And then he turned and saw the demon.

The demon watched him with hungry eyes. Krishna watched him without much concern. Unable to take such apathy, the demon said, “Don’t you know who I am?” Krishna replied nonchalantly, “Looks like you are going to tell me, in any case!”

The demon said, “I am the size of your fear!” Krishna laughed, took out his bamboo flute and started playing. And the demon started becoming small. The more Krishna smiling to himself softly played his flute, the tinier and tinier the demon became, until it was the size of a miniature doll. Krishna picked him up and put him in his bag, closed it, and dozed off.

The next morning when Balram woke up, he woke Krishna, “Krishna, Krishna, thank God we are safe! You have no clue what could have happened to us last night while you were sleeping. A humongous demon came. He was about to eat us.

Krishna yawned a beatific smile with his lotus lips, slowly removed the doll from his bag and asked, “Is this the demon?” Balram was confused and said, “Yes – it looks like him. But he was huge. How did he become so tiny??...”

Krishna said, “He looked so huge because he was able to scare you. He was the size of your fear. I couldn’t help but laugh when he tried to scare me, and he kept shrinking. He would have disappeared, but I wanted to show him to you – hence I have kept him in this miniature form!”

Answer 14

Perhaps the whole can be summarised with Occam's Razor: "Entities must not be multiplied beyond necessity."

If we assume a monster, we assume energy. Energy intake means that on the other end, there is some sort of waste product. If we found in the forest excrement of an unknown source, believing in an undocumented monster might start to make sense. But there'd have to be many such pointers to make an investigation into the monster's existence worth while.

The conclusions we draw from what we experience are perhaps more critical to our world view than what we experience.

Seeing a monster "for real" is much more likely to be someone playing a prank, than the monster's existence. The claim that it exists because a person saw it is also a claim about many, many other things: like why it is that many have travelled this forest, and have never seen this thing.

Once we believe that person A saw a monster, we now probably should believe everyone who says they too saw something undocumented. Soon, our beliefs would be filled to the brim with mythical creatures. And, eventually there'd be so many, that we'd be left no choice but believe none of them, if we want to make any progress toward improving our survival.

If the world is full of monsters, then we should probably invest in protection against them. And we're now creating and putting energy toward an effort that reduces our survival due to poor prioritisation of our limited resources. We're now making protective trinkets rather than building a dam to protect against a flood.

Answer 15

There is precious little philosophy in this answer, none is needed as far as I am concerned. There are many observations about humans that are accessible to all of us to answer the question.

However, why should believe that the person hallucinated? The probability that a given sight is a hallucination is surely something like 1 in 1,000,000.

That number (which obviously is only there for argument's sake) seems grossly optimistic to me.

Hallucination is an extremely common occurrence in humans, both for small, trivial observations, as well as for extraordinary ones.

Only think of all the almost "meme worthy" events where a pair of adult, intelligent people disagree on the simplest and most obvious of observations or memories. The married couple who discusses heatedly in the "he said, she said" mode. Court hearings where witnesses give clearly contradictory accounts of events (even if there does not seem to be an intention to lie, as far as we can tell).

People lie on the grass, stare into the clouds, and "see" things there. Obviously they do not actually believe that there is a dragon flying there, but the brain is obviously very much tuned to see patterns and meanings everywhere (and this can easily be proven by self-inspection).

There are lots and lots of joke pictures (like the familiar one where you see a vase, and if you stare for a while, it suddenly switches and shows two faces instead).

Our brains have different versions of reality - both inside different people, as well as within the same brain: it is easily possible for us to juggle different versions of reality at the same time; for example one version that is "objectively" real (whatever that means, it is not an easy concept), and one that is a different version that we would like to approach. I.e., I can at the same time see that in my reality some fact X is true, but I can also imagine a version of my reality where X is false; and I can even overlay those and build an internal plan of how to reach the second state.

Also, it is clearly possible for many of us to have their own view of reality, but at the same time have enough empathy to be aware of a "mirror reality" that is the point-of-view of a different person.

Anyone who has done meditation (specifically, introspective ones like "awareness meditation" or "vipassana" and so on) can quickly find out that things do not are what they commonly seem to be inside the brain; for example, for most people it is readily accessible that the process within the brain that creates thoughts is not the same as the process which observes these thoughts, and that it is mostly impossible to suppress the creation of thoughts. In fact, asking a meditator to suppress thoughts is a direct route to more thoughts coming up and everything escalating very quickly. When meditating for a long time (i.e., sitting for 10 days / 100 hours), one experiences a great many things that eventually "feel" just as real as "objective" reality.

Drugs are well known to change our perception of reality - especially psychedelics. Songs have been sung about this, pictures have been painted, and drugs like LSD have been looked at scientifically as early as in the 1940's, 1950's.

Sometimes these kinds of different alternate realities overlay, swap, get confused, and so on and forth. Also there are clearly mental illnesses that make all of this different, special, problematic for individuals (i.e., schizophrenia, psychosis, and similar). This does not mean that anybody who sees extraordinary things suffers from one of these, but it shows that there clearly are "features" within the brain and however it is "implementing" the mapping of realities, that can and does go wrong; and it is quite conceivable that this happens occasionally for random people, while they are actually quite healthy.

And finally, it is clearly possible that people are influenced by their environment, education, family and so on and forth to view the world in different ways - only look at most religions and other "fundamental" ideologies. You can't seriously say that those all are actively lying about "facts" that are total fantasy for people not subscribing to those religions or ideologies. Many of them surely actually really believe the most unbelievable things.

And finally finally, people do lie and misrepresent.

Why do we choose to believe something so improbable instead of believing the man's claim?

Because, as show, there are many, many, reasons, that the mapping of "objective" reality inside the brain is not what it seems. Almost all of those I listed are readily available for self-inspection; many are reported by anybody who talks about it in a scientific or just a social setting; and there are whole branches of medical or law science considering the trustworthiness of human experience.

TLDR: trusting the statement of a human, including oneself, is generally an incredibly unreliably thing. Every-day and extraordinary statements always can be taken with a grain of salt; the grain being somewhat proportionally large compared to the claim.

Answer 16

Just looking at the lottery example: If you win, it was either incredible luck, or cheating. And with a one-in-14-million chance of winning by luck, assuming cheating doesn't seem unreasonable at first sight.

However, in the UK, there have been about 360 lottery winners in 2023, and not one serious accusation of winning the lottery by cheating. So it seems that cheating at the lottery is very difficult. Most people think it's so difficult, they don't even bother looking at possible ways to cheat. And the few that look for ways find that it is very, very difficult. So it seems to me that the chances of some person declared as lottery winner being a lottery cheat is less than one in 100.