Lack of Evidence is Not Evidence of Lack

The most predictable thing has happened. This fall, Covid-19 finally reached my city. The hospitals are filling up. The people in charge did nothing to prepare. Correction, worse than nothing. As in many places they were happily cutting health and education budgets right up until it hit.

That aside, among the platitudes they are now using is one that is simply and obviously misleading. It always begins with, “There’s no evidence that…”

As in, “There’s no evidence that Covid-19 is spreading in schools.” (Even though schools are enclosed spaces with large numbers of people close together for long periods of time. )

This drives me crazy for two main reasons.

  1. I want to add “yet” every time I hear it. It’s just a matter of time. Why wait? Why not prevent an outbreak? Why wait on incontrovertible proof that what has happened elsewhere will happen here too? Why not be proactive and protective, rather than painfully reactive.
  2. It’s actually a well-known fallacy. And pure, bad science.

Photo by Rosie Kerr on Unsplash

“Absence of evidence is not evidence for absence”

This quote is often attributed to Martin Rees, and was popularized by Carl Sagan. I first heard it in the context of archeology as, “Lack of evidence is not evidence of lack.” It was referring to the everyday activities that leave little trace in the fossil record but must have existed (e.g., most things).

In this case, it is a type of “argument from ignorance,” a concept that is traced as far back as John Locke in the late 17th century. Let’s Wikipedia it real quick. (Can Wikipedia be a verb? or does that undermine my credibility?)

It asserts that a proposition is true because it has not yet been proven false or a proposition is false because it has not yet been proven true. This represents a type of false dichotomy in that it excludes the possibility that there may have been an insufficient investigation to prove that the proposition is either true or false.

This sort of statement should make people ask — are you looking? What sorts of investigations or research is being done on this? Are you testing in schools? The fact that they have not (yet) confirmed school transmission means nothing.

Further, at what point do we cross the line to willful blindness? Or are they all just trying to maintain plausible deniability?

So, don’t buy into this sort of insulting rhetoric. Call it what it is when you see it. Now you’ll have the fancy terms (and Wikipedia links) to back you up.

Stay safe, stay sane.

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