Prior Plausibility: How to First Assess Claims

A necessary tool in the scepticism kit is prior plausibility (or probability). I’ve mentioned it before, but not sure I’ve explained it well. It’s a good starting tool for consumers to be protected from scams, fads, influencers, nonsense etc.

The term is a shortcut to forming a quick estimation of the truth of a claim. It must be used correctly, of course and in good faith. Importantly, it is linked directly to ‘what we already know to be true’. It’s how I am often able to confidently dismiss or be sceptical of a claim without first digging far into it.

Prior plausibility in science is not just a guess. It’s informed by the existing body of scientific knowledge – the well-established and high confidence stuff, primarily. From there, if the claim passes the lowest bars of plausibility, then it may indicate there’s something worth checking out; providing there are no further serious reasons to doubt the claim.

Prior plausibility can often be the difference between outright dismissal and provisional acceptance of a claim. The dismissal can also be provisional – pending compelling evidence of course. Similarly, the acceptance can be tentative, not something you’d put money down on but something you’re not yet willing to rule out completely. Again, this is subject to further compelling evidence being found.

I’ll now use several examples where different levels of prior plausibility can be used to make a shortcut judgment of various claims, explaining why you can have such levels of confidence in rejecting certain ones outright. This dismissal can often appear arrogant and ‘superior’ to those who do not understand why the claims are not plausible; those who do not exercise prior plausibility.

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Low Prior Plausibility 

Alien Visitation

Herbs, Supplements, Remedies

Detoxes, Juice Cleanses

Perpetual Motion/Free Energy Generators

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High Prior Plausibility

Vaccines

Fluoride for Dental Health

Einstein’s Theory of Relativity – Spacetime Exists

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What informs prior plausibility?

A little knowledge always helps distinguish plausibility, but this isn’t readily available for a lot of people. Some understanding of scientific concepts and logic, critical thinking, etc., goes a long way. But there are still plenty of ways to make better decisions as an average consumer of information. I wrote a whole post about that if you are interested.

Judging prior plausibility requires a little knowledge of the topic, a little critical thinking, and a little understanding of what qualifies as evidence – and how to interpret it. It sometimes easier to have a bit of knowledge of things that are just wrong – not necessarily right (which is usually a tougher answer). Think of it like a jigsaw – you could test 50 pieces to fit another piece, knowing confidently that each one prior to the correct one was wrong. However, you might not know the right one yet. But this doesn’t stop you from identifying which pieces are wrong.

Above all, try to judge claims that spring up out of nowhere against as many scientific sources as possible. Where there is no criticism to be found, or no information at all other than touting a plethora of benefits, or anecdotes, it’s likely a red flag – low plausibility. If you don’t have enough information, then there’s no shame putting the claim on hold and sitting on the fence.

Here is a rough table which would inform the appropriate level of scepticism to apply to claims, based on their prior plausibility, much like I have done in the examples earlier.

Prior Plausibility (informed by science)	Level of Scepticism
Zero plausibility ·         Homeopathy ·         Reiki or other undetectable ‘energy’ ·         Free energy devices	Don’t waste another second! Dismissed!  Flies in the face of basic scientific facts, uses broken logic, invents nonsense and poorly defined, unproven or disproven, or untestable concepts.
Very low plausibility ·         Dubious/unstated mechanisms. ·         Conspiracy Theories without evidence. ·         Contradicts previous body of evidence.	Very high scepticism  Obvious red flags and contradictions of prior knowledge without backing it up.
Low plausibility ·         Claim is unproven but makes money. ·         More questions than answers. ·         Logical inconsistencies in reasoning.	High scepticism Insufficient evidence, patterns in reasoning or evidence similar to other debunked claims. Running with the hype before substantiation.
Difficult to tell but plausible ·         Small studies, case studies. ·         Not ‘impossible’ by current knowledge. ·         No immediately obvious contradictions. ·         Recognises limitations. ·         No hype/certainty. ·         Too much hype/certainty.	Be Sceptical Seek better info. Claims made without strong evidence have less merit than a 50/50 chance, because of the many ways we can be fooled or be wrong. Confirmation bias is rife in this category.
High plausibility ·         Consistent with prior scientific findings. ·         Criticisms/limitations addressed appropriately. ·         Passed preliminary testing and studying with positive results. ·         Claims are in line with the current evidence and don’t overshoot it.	Low scepticism  Still a relevant degree of it until sufficiently demonstrated. Tentative acceptance of the claim is ok, but low certainty.
Very high plausibility ·         Independently replicated among science institutes globally. ·         Larger effect than placebo. ·         Well-controlled and designed studies (double blind, randomised, large study).	Scepticism not very necessary  Subject to checks and verification. Provisional acceptance of the claim is safe.
Established, demonstrated scientific knowledge. ·         Scientific Theories (Evolution, Relativity) ·         Scientific Laws (thermodynamics) ·         High certainty. Predictive.	Zero scepticism required Highest bar of scrutiny passed. Scepticism would be wasted time, inappropriate and counter-productive. It would actually indicate insufficient understanding of the topic to be sceptical of a scientific consensus of evidence.

Although my above explanations are hopefully adequately simplified, a better, more comprehensive explanation can be found in the below embedded post – and click through into the full article. It’s written by a scientist, with an even greater understanding of the concept than me. Well worth the read:

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Conclusion

One of, if not the first thing that should be considered if you want to know the truth of a product or likelihood of a claim, is prior plausibility.

It’s a tool you can apply on a detailed level if you’re well-informed, or on a lay persons’ level with a bit of digging.  Time, effort and money is wasted all too often by consumers of information without the necessary checks in place, and the more gullible we are, the more at risk we are personally, and to those close to us – merely of being fooled, if nothing more serious.

If we are too quick to judge a claim as favourable, then we tend to skip the checks and incorporate it into our identity for the time being or our social standing. This makes it difficult, but never too late, to rewind and pause a second, check that we aren’t first deceiving ourselves. It’s much better to address it sooner, than to fall irreversibly deep into an idea and then have to back out.

I’m sure nobody likes to be perceived as gullible, much less likely be gullible. But that doesn't mean we should ignore it when it inevitably happens from time to time. In order to learn from these kinds of mistakes, we must be humble to ourselves, and acknowledge the error such that it can be recognised the next time.

Dismissing a claim with low prior plausibility and a healthy level of scepticism is not a cynical, killjoys’ game, ideological, or close-minded.

Dismissing a claim with low prior plausibility is retaining one’s own power, consumer protection, and a privilege we should practice and celebrate intellectually.

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