It's established that the burden of proof rests on the party making a claim.

The problem I find, is that for any conspiracy theory - the proponent can point to a multitude of conspiracy websites or videos, and say 'Look! Here's the proof! It's all here!'.

It's then a time consuming exercise to examine the proof and refute it. More so - I myself, don't have the expertise to evaluate these claims either way (in the case of 9/11 building collapse theories for example).

A tempting response is to not acknowledge the evidence, because of the source 'This is obviously a conspiracy theory website, show me a mainstream scientist making these claims'. But this is an appeal to authority fallacy.

What is the correct, pragmatic, reasoning response here?

To elaborate, let's follow this with an example.

Bob claims that there are fairies at the bottom of his garden. I say 'The burden of proof is on you - show me the proof'. Bob directs me to a website, that has videos of witnesses claiming they've seen them, reports of inconsistencies about the official story regarding the fairies, sketchy videographic evidence, and a 30 page lab report about something that I don't understand.

One option here is - I can go through, spend all the time, get to understand the report, and conclusively refute the hypothesis.

Then, when Bob next makes a similar claim, I can say 'Well look, your credibility is shot, the methods and reasoning that were used last time weren't scientific, so I'm going to no waste my time again here'.

Any other thoughts?

  • First, burden of proof is only established in very limited domains. If someone makes the claim that Simulac baby formula is toxic, and if the claim is serious and plausible, then the burden of proof falls on all parents. The burden of proof rather lies on those who care about the certainty of the answer. Nov 17, 2013 at 16:40
  • Second, I think to get at the crux of your question, when an individual, namely you, are trying to evaluate the claims of a group of conspiracy theorists on the internet one on one, then yes the task would be time-consuming and difficult to do correctly. But the resolution to this problem is for the claims of a group conspiracy theorists to be countered by a group of skeptics, like the Debunking 911 site (debunking911.com). Nov 17, 2013 at 16:47
  • 4
    There is a sister-site skeptics.stackexchange.com, of which you may be aware. Some of the users may have ideas (perhaps based on experience). Perhaps something to (also) try out in their chat or meta?
    – user3164
    Nov 17, 2013 at 19:06
  • @Transmissionfrom - I initially was going to post this at the skeptics stack exhange,but that SE is for refuting specific claims, not questions about skeptic reasoning.
    – dwjohnston
    Nov 17, 2013 at 19:14
  • 1
    @dwjohnston That's why I suggested chat/meta. :) (See here for something similar.)
    – user3164
    Nov 17, 2013 at 19:17

8 Answers 8


What you're touching on, of course, is a couple of basic facts about epistemology — and how they impact the activity of proseletysation: the attempt to get someone to believe in an idea (whether religious or secular) which they not only did not know, but did not even concern themselves with, before.

The short version is that because original discovery of knowledge is difficult, we have systematically done out best to substitute discovery with learning from others. This makes knowledge socially contingent, and therefore based on reputation.

Discovering knowledge is hard. So hard, in fact, that we have developed several interoperating institutions whose purpose is to preserve knowledge which we have won, and to try to disseminate it much more efficiently than it could be independently re-discovered by anyone who might need it. Meanwhile, we pay researchers moderately generous salaries (much less than programmers, medical doctors, and financiers, mind you, but generous considering their outwardly apparent output) to take the risk of brain damage involved in spending long periods of time trying to discover things.

Knowledge of sufficiently complicated topics is socially constructed. The ideas of 'trust', 'faith', and 'teaching' are predicated on the idea that we can take as candidate "facts" things which we have never experienced, but have been told. In this sense, we defer the obligations for knowledge to others — we make knowledge dependent of social relations.

Application to proseletysation. Suppose you want to apprise someone of a new idea. In trying to provide them with 'knowledge' by social means, you must have one of the following two resources: concision, or reputation. If your claim is outlandish, but the explanation is short and sweet, I may humour you just out of curiousity because the cost to me is low. Otherwise, if your explanation is long and complex, I will only investigate it if I have some good reason to give you the benefit of the doubt: for instance, if you are widely recognised by society as a trustworthy speaker on the subject (e.g. you are a famous scientist, you are a teacher at the school and your audience is your class, etc.)

If a conspiracy theorist wants to convince you of something, they should either present it very calmly and soberly (or convince you of short separate pieces of their reasoning which can stand alone) in order to build up your trust in them, or they must provide a very short and compelling explanation of their theory. Otherwise, even if their claims are true, they are asking you to make an unreasonable expenditure of your time and energy as an information-gathering agent for one very specific piece of knowledge — if indeed it is knowledge, i.e. a faithful representation of reality.

This is true not just of conspiracy theorists, but also of religious enthusiasts, and technical enthusiasts — it is unreasonable to ask your friends to share one's excitement for (or vehement rejection of) Jesus Christ as your saviour; and unreasonable to ask one's relatives to develop highly specialized knowledge of the operating system on their computers, if they have computers. There are exceptions in both cases if it is highly relevant to their lives, but if it requires them to spend a lot of attention or to overturn a lot of ideas of how things work, then it will be labour-intensive for them, and one's request should be made giving this fact due respect.

In short, anyone who is asking you to believe in something, is asking you to make an effort. They are requesting a favour from you (the aspects of what makes belief in an idea a 'favour' is itself an interesting idea, but never mind that) in the attention you spend on them. If they want you to do them that favour, the onus is on them to make sure their request is reasonable, in that it is not a social imposition. If they develop a reputation for social impositions, that's unfortunate — but repairable, to the extent that any reputational damage from social transgressions can be repaired.

On noisy learning environments. On the case of penicillin and the Pasteur Institute mentioned by Michael in his earlier answer: we have in that case the unfortunate situation of an environment which was, for the Pasteur Institute, hostile to learning, in that it was subject to a lot of noise by (possibly even well-meaning) cranks. It is not immediately clear what they should have done in the face of such stimulus. There are similar problems in computational complexity and proofs either of P = NP or P ≠ NP: because there are so many well-intentioned (but poorly trained) people who continually attempt to prove it, and who cannot even be induced to learn from their mistakes, the very question has a taint upon it, so that there is a high reputational burden involved in being taken seriously.

Thus we see a second-order ethical obligation to conspiracy theorism (or interests which diverge from the norm, generally): not only should you be respectful of the attention which your audience is literally paying to you, it is your social responsibility to be careful in how you engage in your conspiracy theorism, lest you poison the well for others who may come after you, and thereby inadvertently hurt society.

Again, I think that this responsibility is not just upon conspiracy theorists and amateur scientists.

  • One of the major reasons why there is as much distaste for mathematics, and wilful innumeracy, in the general population, is because (a) tremendous emphasis is put on the importance of mathematics to make math education mandatory, but (b) it is not taken seriously enough to ensure that the teachers of mathematics are up to the job demanded of them. Students feel their time has been wasted, and conclude that mathematics is likely to be a waste of time. And they then take pleasure out of being part of a majority of people who feel that way.

  • The reason why such genres of entertainment as comic books, science fiction, etc. have been held in disdain at various points in time, is largely because the well has been poisoned by a small fraction of well-meaning enthusiasts, who ruin the subject by association through their overexuberance.

This is profoundly unfair, but it is better to recognise the fact, because without completely overturning the ways in which information is collected and distributed (and how would one begin to do this without confronting the social nature of knowledge?), it is unclear how one can avoid such problems.

  • +1 for "wilful innumeracy" as one of the causes for the situation. :) Now a natural follow-up question: is it possible to tame that problem, if not innumeracy itself but at least the impact of the wilfully innumerates on the society? For example, would it be socially acceptable to make voting rights subject to passing some minimal literacy and numeracy requirements?
    – Michael
    Nov 18, 2013 at 19:02
  • 1
    @Michael: er, I think this is wandering a bit far from the scope of the OP in this case. But in any case, while numeracy is certainly helpful for being well-informed, and well-informedness is productive to making productive democratic decisions, I don't think there is a binary distinction between well- and non-well-informedness (nor between numeracy and innumeracy), so such tests would serve largely to discriminate against those demographics who have been, by design or by happenstance, poorly served by the educational system. Nov 18, 2013 at 20:14
  • 1
    @Michael: also, I think that while it is a positive feedback loop, the fact that we could (and should) select for competent mathematics teachers means that the innumeracy in the general population could be mitigated in the problem of finding good teachers, if we made it a high enough priority (i.e. we were serious about teaching mathematics, rather than appearing to teach mathematics). So I would sooner describe wilful innumeracy as an effect of not respecting student's attention, as opposed to a cause; though it may be a partial cause in the other phenomenon of conspiracy theorism. Nov 18, 2013 at 20:16
  • There is a certain amount of social pressure against numeracy. I think psychological drive here is similar to the drive to socialize everything by the poor. How are you going to make teaching of Math a priority when priorities are set by such a crowd? You cannot hear the voice of 10% of reasonable men in the chatter of 90% confident in themselves innumerates.
    – Michael
    Nov 18, 2013 at 21:21
  • 1
    "Discovering knowledge is hard" - I don't buy this blanket statement. Even infants discover knowledge quite easily.
    – user18800
    Jan 4, 2016 at 22:08

The answer depends highly on what position you hold in regard to evaluation of conspiracy theories' claims. Let me present the following example.

Science was making huge strides in the late 19th century, including revolutionary discoveries by Louis Pasteur and his followers. That opened an opportunity for numerous hustlers to claim discoveries of magic potions that would cure numerous diseases. There were so many of those that reputable institutions, such as Institut Pasteur, would not even respond to them.

In 1897 Ernest Duchesne, and unknown 23-year-old soldier, sent a thesis to Institut Pasteur, claiming that Penicillium glaucom can be used to cure typhoid. This outrageous claim was not even acknowledged, and Penicillium remained unknown for 20 more years, and its use in medicine was not appreciated for 30 years after Duchesne's ill-fated thesis. During those decade millions have died of typhoid and syphilis that could have been cured if the recipient of Duchesne's letter provided due diligence.

I agree with Julien that the probability of any given conspiracy theory is wrong is much higher that its validity. However, one has to consider not only the alternatives, but also the cost to humanity of making a mistake. Just as in Game Theory, that matters is not whether P1 < P2 or vice verse, but whether P1*C1 < P2*C2 or vice verse, where P is probability and C is the cost.

And because the cost to humanity of you making a mistake depends on your position so does your due diligence. If you are just chatting with conspiracy theorists for pleasure just follow Julien's advice; however, if you are in charge of a relevant investigation you'd better keep your mind wide open.


The argument that one is justified to dismiss conspiracy theories (CTs) outright, simply by virtue of their being conspiracy theories, is not convincing.

This argument is generally attributed to Brian Keeley (1999). He posited that CTs share a number of traits, which lead the believer in CTs towards a sort of epistemic nihilism, resulting in doubt about everything. However, he introduced the categories "warranted" and "unwarranted" CTs, without clarifying how to distinguish the two, although the two categories share the same epistemic traits.

The particularist point of view, proposed by Charles Pidgen and others, argues that there is nothing about CTs, if they are based on evidence, to justify outright dismissal. Clearly, many historical events were the result of conspiracies. The general usage and more common definition of conspiracy theory is that it offers an explanation different from an official version. Given that so many conspiracy theories are political, this means they often contradict the government's version or position.

I would further add that CTs usually lack support from media and academia, institutions that form the backbone of society's epistemology. However, to interpret this lack of institutional support as proof of a particular CT's irrationality is a mistake.

Given that opinions and beliefs are socially construed, to speak in favor of a particular CT carries social sanctions. To publicly profess support for a CT may even hinder professional advancement in the media and academia. Further, science in academia is often funded by government agencies. We must not assume that some scientists who have expertise to evaluate a set of data that is important to a CT will actually be motivated to do so, and if some are so motivated, we cannot assume that the scientists will act on principle to risk of career growth.

Further, the potential negative consequences for contradicting an official version/story varies among scientific fields. The potential negative consequences are greater in fields in proportion to the field's reliance on government funding for research and other projects.

For these and other reasons, we cannot necessarily rely on academia to evaluate the evidence presented in CTs although many credentialed professionals, with qualifications in an appropriate field, do believe in and speak out in support of a CT.


I understand your frustration with trying to satisfy the twin goals of open-mindedness and rational rigor. The worry of committing the "Authority fallacy" leads some of those who highly value indiviudal rationality to feel the need to be perpetual investigators. However, from a practical point of view, it is not possible to thoroghly evaluate all claims either due to lack of knowledge and/or resoures. Hence, appeal to authority is inevitable for EVERYONE. For example, who actually reads all the medical literature before taking ibuprofen? Have you convinced yourself that it is safe, or are you taking the FDA and your doctor's word.

My guess is that, like all but the most paranoid, you probably follow your doctor's adivce without too much skepticism, especially if it prima facie makes sense. The same goes with scientific findings or textbooks. I don't know how many engineers bother to personally verify newtown's laws before builidng a bridge, as a simple example.

Therefore, for most people, there are limited areas where we can personally verify a claim, the rest we rely on suitably chosen and vetted authorities. Why do we trust doctors? Probabliy becauses we trust the medical decision making model and the scientific process that supplies the raw data for their decisions. If something doesn't work or is wrong, it is likely to be pointed out very quickly in the highly competitive environment of medical and scientific research. In general, we trust an authority because they utilize methods that have a high probability of finding true, or at least accurate, data.

So, for conspiracy theories, I too reject them outright unless they have peer-reviewed documents or can provide not only "data" but can establish that it was collected by a process that has a high chance of producing the truth.


What is the correct, pragmatic, reasoning response here?

Ask the conspiracy theorist to make predictions which he/she can then verify. It is extremely easy to come up with just-so stories of extant evidence. It is much harder to predict new, unexpected things. "Based on what I think I know, I should find this over there." If that thing is found, then there appears to be some knowledge in "what I think I know".

A possible exception to the above is if a wide variety of evidence can be systematized with a very 'small' model. The trick is to properly evaluate a model as being 'small'. Karl Popper's ideas on falsification are probably helpful, here. What makes a theory powerful, in his mind, is that it rules out a lot of possibilities. That means that plenty of logically possible observations will never be made, and therefore there are many ways for the theory to be disproved. Contrast this with conspiracy theories, which appear to be able to absorb and explain just about any observation.

  • Can you make a similar request of historians? For example when historians say 'At the boston tea party, a bunch of men dressed as indians and threw the tea overboard, their motives were... we know this because it's documented in the following...'. This is the historians model of what happened in the world. However, we can't really expect them to make any prediction from this, but this doesn't discount the veracity of their model.
    – dwjohnston
    Jan 15, 2014 at 21:28
  • The historian's model is still falsifiable though, unlike the conspiracy theorist who can always come up for a reason why it was that way. So I think this falls under my second paragraph?
    – labreuer
    Jan 16, 2014 at 1:04
  • Another example was "Moon landing". What could one possibly predict therefrom? In fact, the Moon landing is totally irrelevant for the majority of humans. Hence in such cases, I wouldn't even try to disprove. I couldn't care less would be a more appropriate answer.
    – Ingo
    Jan 16, 2014 at 16:02
  • @Ingo, we can fire lasers at the moon and hit retroreflectors placed there, which is surely some kind of evidence. My second paragraph also applies. And yep, if we aren't predicating any actions on whether it happened, then it [probably] doesn't matter.
    – labreuer
    Jan 17, 2014 at 3:42
  • @DavidBlomstrom: There has been a tremendous amount of work on what qualifies as good history and I've only seen bits and pieces. What I surmise is that you want simple models with redundant evidence so that as more artifacts are unearthed, they largely corroborate your current model. See Wikipedia's Bootstrapping (statistics). But falsifying evidence is not the only metric historians use to prefer one model/​explanation over another. It's probably just the simplest!
    – labreuer
    Sep 17, 2018 at 17:21

Maybe we can follow Hume and his thoughts about miracles.

Evaluating the truth of theories of the kind you mentioned can be done by comparing the probability that they are true, with the probability that the witnesses are hallucinating, mistaking or lying.

Generally, you don't need to go in a very deep analysis, and a very rough estimation of those probabilities will give you a simple answer. If it is not the case, it means that you have to go through a detailed analysis of all the arguments.

In the case of Bob's fairies, you have to compare : 1. The probability that Bob and other witnesses have made a mistake, even if they are truly convinced of what they saw, accounting for the propensity of human beings to believe fabulous stories; 2. The probability that fairy exist, but are not related to any other kind of animal or entities regularly observed, and were only observed by a very limited number of common individuals, who cannot produce a clear evidence.

In my view, P1 >> P2.

If you think P1 is of the same order of magnitude as P2, then good luck.

  • 1
    +1 Although I believe the question is not what to believe, but rather how to treat the conspiracy theorist (fairly?).
    – user3164
    Nov 17, 2013 at 19:31

You aren't being very specific in saying what you mean by a conspiracy theory. This is a common problem in discussions of conspiracy theories. They are usually taken to mean something like "an account of some event that is different from the norm and somehow involves some kind of conspiracy".

But there is a bright line that separates some theories labelled in that way from others. If a conspiracy theory claims that

  • a major historical event, such as 9/11,
  • was arranged in secret
  • by people who stood to gain from the event
  • and who conceal their motives in public,

then it is a bad explanation regardless of the specific details of the claim. 9/11 conspiracy theories typically fit this pattern. Bush, or the Mossad, or Wall Street bankers somehow arranged 9/11 or let it happen for some reason like making money, or engaging in a war for oil or something like that. But Bush pretends to be all broken up about it and says he is going to stop the terrorists when really he just wants their oil.

Try to ignore the gross stupidity of the alleged motive in this case, and think instead about how Bush would go about arranging 9/11, and what will happen after the event.

How can he go about recruiting members of the conspiracy? "Hi. I was wondering if you wanted to participate in the cold blooded murder of thousands of innocent people so I can get some oil."

The conspiracy theory says that the conspirators act in public as if they believe their lies. But so do people who are taken in by the alleged conspiracy. So the conspiracy theory doesn't explain the behaviour of anybody. Also, how does the conspiracy theorist know about the conspiracy when everyone acts as though there is no conspiracy?

And how do the conspirators stop each other from ratting the others out? And how do they distribute the spoils of their conspiracy? They can't use standard contract law since that would require making the conspiracy public.

There are other flaws, but the above are the highlights of the linked article.

  • in this post you pose your own personal motivations and you are not answering the question. You seem to ignore that the is no scientific consensus in the case of 9/11 and there are plenty of inconsistencies in the official story.
    – user22051
    Sep 17, 2018 at 14:28
  • @PbxMan The post says nothing about my motivations. What you say about scientific concensus or lack thereof is irrelevant since my criticism is about how Bush would go about arranging the conspiracy rather than alleged scientific problems. And if the official story was wrong that would still not make any of the problems I explained go away.
    – alanf
    Sep 17, 2018 at 14:36
  • @ alanf you categorised the 9/11 truth movement as "stupidity". Let me remind you that there are 3000+ Architects and Engineers demanding a new investigation.
    – user22051
    Sep 17, 2018 at 14:39
  • @PbxMan I said the alleged motive of the alleged conspiracy was stupid. Do you think waging a war for oil or to make money isn't stupid?
    – alanf
    Sep 17, 2018 at 14:43
  • not at all. Wars for power and money have been happening since the dawn of time. Have you read the PNAC?
    – user22051
    Sep 17, 2018 at 14:45

According to wikipedia:

A conspiracy theory is an explanation of an event or situation that invokes a conspiracy—generally one involving an illegal or harmful act supposedly carried out by government or other powerful actors—without credible evidence.

Conspiracies happened in the past (e.g. Assassination of Julius Caesar ) happened in the recent times Gulf of Tonkin Incident, Nayirah and will continue to happen. These last two are no longer considered "theories" because they have been validated by mainstream media and reputed historians.

It is that "credible evidence" what turns a conspiracy theory into a real conspiracy. Keep in mind that not always scientific consensus makes something credible, take for example creationism (38% of the Americans still believe in it) and climate denial (34% of Americans think scientists seriously disagree about climate change).

Also keep in mind that people have trouble accepting the truth when it comes to events which are hard to accept because the mind is not efficient at looking for the truth when you are emotionally attached to a result or idea. When this happens you may get mental phenomena such us motivated reasoning, confirmation bias or cognitive dissonance that prevent you from having an unbiased research. The more you want things turning out the way you want the harder it gets.

I'm afraid that there is no an easy way to dismiss "conspiracy theories" as fake all the time unless you do your homework or expect those ideas to be accepted or rejected in time by popular culture. Sometimes the truth is told when it is no longer relevant.

"The truth is not for all men, but only for those who seek it." Ayn Rand

"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." Demosthenes 384-322 BC

  • Well, the reason for accepting creationism is typically religious. It is hard for these people to accept God could be wrong or deceitful that they choose to believe those are imperfect humans who are wrong or deceitful. However, we know that God (or the ones who authored Genesis) can't be consistent in his words after reading a couple of chapters of Genesis.
    – rus9384
    Sep 17, 2018 at 19:48
  • Also, the climate denial source shows that 34% of people do not believe scientists agree on climate change. This is not climate denial. And climate change is hard topic, because it happens continuously, what is discussed is serious climate change.
    – rus9384
    Sep 17, 2018 at 19:52

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