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Epistemic Trespassing: Stay in your lane mf

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In this blogpost, I focus on the problem of epistemic trespassing. This happens when experts step outside their field of expertise and pass judgment on questions in fields where they lack expertise. Philosopher Joshua DiPaolo recently argued that epistemic trespassing is wrong insofar as it constitutes an abuse of expert authority that neglects novice vulnerabilities (1). I agree with DiPaolo and think that it's something more people should know about, especially at a time when a lot of knowledge is specialized and we--novices--often depend on experts for answers. So, below, I share a tragic example of epistemic trespassing that illustrates its harmful potential and very briefly consider possible solutions.

Consider the following:

A mother’s two infant children die suddenly and without any explanation. She’s charged with their murder and in court two possible explanations are considered: (i) that the infants died due to the rare sudden infant death syndrome (SIDS) or (ii) that she murdered them.

To help in this matter, a paediatrician is called to the stand for his expert testimony and he proceeds to answer a question about the statistics of SIDS.

The paediatrician says that the chance of sudden death for one child, from a professional non-smoking family, is 1 in 8,500 and that the chance of sudden deaths for two children is 1 in 73,000,000.

However, there's a problem with the expert’s testimony. He wrongly assumed what statisticians call the principle of independence and so simply squared the probability of one sudden death in order to determine the probability of two sudden deaths in the same family. But if a family suffers one sudden death, then you’d expect them to be at high-risk for whatever environmental and/or genetic factors might underlie SIDS, and so increase their chance of suffering another sudden death. And yet, the expert didn’t factor any of that information into his consideration.

As the statistician Peter Donnelly put it:

If a paediatrician had’ve come out and said to a jury ‘I know how to build bridges, I built one down the road, please drive your car home over it’. They would’ve said ‘well paediatricians don’t know how to build bridges, that’s what engineers do’. On the other hand, he came out and effectively said or implied ‘I know how to reason with uncertainty, I know how to do statistics’, and everyone said ‘well that’s fine, he’s an expert’. (2)

Unfortunately, no one questioned the paediatrician about his erroneous testimony and the mother was later wrongfully convicted of murdering her children (she was eventually released after a second appeal).

So, that's a clear case of epistemic trespassing because the expert’s error, in reasoning with uncertainty, is demonstrative of his non-expertise about questions concerning statistics.

It’s important to notice that he didn’t trespass by asserting someone else’s opinion on the matter. For it to count as epistemic trespassing, trespassers must do it on their own and, above, the expert trespassed using his own ineffective skills in passing judgment on a question he wasn’t expertly qualified to answer.

Of course, this could’ve been avoided had the court instead asked a statistician rather than a paediatrician but it goes to show just how easy it is for epistemic trespassing to go unnoticed and have harmful consequences. Most people, like the paediatrician, are novices in statistics and so are typically bad at reasoning with uncertainty. Hence, they were vulnerable to epistemic trespassing, whether or not it was done intentionally.

As we’ve seen in the above example, epistemic trespassing can seriously harm individuals. What we haven’t considered is how it can harm society at large. During the pandemic, we’ve all likely witnessed numerous instances of epistemic trespassing but which we perhaps didn’t recognize as trespassing at the time. The problem is that epistemic trespassing can prevent or distract us from addressing important issues like climate change, economic instability, and global health issues. For that, we may need to implement systemic changes, with appropriate checks and balances.

That said, I guess the best thing we can do is raise awareness and change our educational system. For working professionals, we could (maybe already do?) provide some required training, like courses and workshops, as part of their continued professional development. For students, we could change the curriculum to include such training as a program requirement. But, for now, I just want to use this opportunity to say to any experts reading this: stay in your lane mf!


  1. DiPaolo, J. (2022). What's wrong with epistemic trespassing? Philos Stud 179:223-243
  2. Donnelly, P. (2007) How stats fool juries. TED.

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