A Skeptic’s Guide to Conspiracy Theories

This article first appeared as a Vic Skeptics discussion pamphlet.
The full range of our discussion pamphlets (and a lot more) can be downloaded from our USEFUL INFO page.

A Skeptic’s Guide to

by Peter Barrett, Canberra Skeptics (2016 edit by Ken Greatorex)

Test 1: Is the argument factually correct?

It’s remarkable how many conspiracy theories are based on arguments which are simply factually incorrect. If you’re presented with a conspiracy theory argument, check the facts.

[Sites such as




are useful here.]

Many incorrect arguments are repeated in ignorance. But there are also some people who knowingly repeat conspiracy arguments they know are wrong.

Test 2: Is the argument relevant to the theory?

A second problem with conspiracy theories is that people cloud the issue by attaching true, but irrelevant, arguments. Just because an argument is true doesn’t mean it’s relevant to the theory you’re testing. This is a form of guilt by association, [https://en.wikipedia.org/wiki/Association_fallacy]

and suggests the theory is being padded.

Test 3: If the argument is true, what implications does it have in other areas?

An argument on its own may appear to be plausible. But if we apply the argument to related fields or subjects, does it continue to make sense? Or would it require the world to be very different from how we see it?

Test 4: Is the argument consistent with other arguments used to support the theory?

There’s a temptation to judge a theory simply by the number of supporting arguments.

But amongst all these arguments, there’s the danger that some of them contradict each other. This immediately means that at least one of the arguments is wrong, but in the context of conspiracy theories, it’s perhaps worthwhile doubting both.

Test 5: What do relevant experts say about a particular argument?

Conspiracy theorists often tout their apparent expertise with a body of knowledge in order to bolster their arguments. But, perversely, they also often dismiss other expertsin the field. This is often because the expert consensus in that field is contrary to the argument presented. Similarly, they sometimes quote experts speaking inaccurately outside their field of expertise.

Test 6: Is it an argument or an opinion?

An argument which merely expresses an opinion, but which doesn’t have any supporting evidence, adds nothing to the theory, and should be ignored. Conspiracy theorists are certainly entitled to their opinions, but they’re not arguments.

Test 7: Does the argument offer any supporting evidence?

Some arguments are presented with words such as “could have” or “maybe”. Without any supporting evidence, these aren’t arguments – they’re speculation. They too should be ignored.

Test 8: Is the explanation provided by an argument the only possible explanation for the evidence?

There are cases when an argument presents two alternative explanations for an event.

One is the conspiracy explanation, while the other is said to be the official explanation.

When the official explanation is debunked, the conspiracy explanation appears to be correct by default. But sometimes the official explanation is something different, or misrepresented.

Test 9: How does the argument deal with positive arguments which contradict it?

Theories aren’t built out of opposition to other theories. Instead, they’re created to better explain the evidence than previous theories. Therefore, a conspiracy theory has to address evidence which contradicts it. Ignoring the evidence should be treated as a major weakness of the theory.

Test 10: Would an experiment of your own help shed light on an argument?

Some conspiracy arguments rely on you accepting them without question, perhaps by an appeal to common sense. Sadly, common sense can lead us astray. This is where simple experiments, or even just careful observation of the world around us, can help test the accuracy of an argument.

Conclusion: Is the conspiracy theory a coherent theory?

A problem with many conspiracy theories is that they exist only as a challenge to the official version of events. Yet if the conspiracy theory is true, a series of events must have occurred to make the conspiracy happen. However, many conspiracy theorists are unwilling to spell out exactly how they think the conspiracy was achieved. This appears to be a tacit acceptance that their arguments don’t add up to a coherent theory. What they often have, instead, is an ad hoc collection of arguments which, if put together, make no sense.

2 Responses to A Skeptic’s Guide to Conspiracy Theories

  1. Tim Harding says:

    Here is my contribution. The Scientific Conspiracy Fallacy | The Logical Place

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