The Path from Belief to Knowledge: 5 Levels of Certainty

how to think like a scientist

An old friend of mine recently told me that video games are harmful for my kids’ brain. When I asked him why he thought that, he didn’t bring up some scientific data or research. Instead, he pointed to an acquaintance of ours whose kids are gifted and guess what? They never play video games.

I was flabbergasted.

How can a university-educated man show so little critical thinking and make such unbridled inference? Of course, I quickly made him admit that a ton of other variables could play a role here. And even if a correlation existed, as any college freshman knows, it wouldn’t imply causation.

This story highlights one important fact about belief and knowledge.

As Gary Marcus shows in Kluge, humans often believe first and think later, rather than the other way around. In other words, once we decide that something is true (for whatever reason), we’ll look for reasons to support that belief. The conclusion comes before the premises.

This is a fascinating topic, which I’ll explore in a future post, but today I want to talk about the truth. No less.

How can we make sure that A causes B? How do I know if video games will really damage my kids?

Here are 5 degrees of certainty.

  1. Anecdotes. People just love anecdotal evidence (ex: this cured my brother-in-law), because it’s vivid and personal. But understand this, it’s the weakest kind of proof you can offer.
  2. Experts’ opinion. Experts’ knowledge is more comprehensive, but it often suffers from biases.
  3. Empirical research. This is where beliefs start becoming knowledge, but its reliability level greatly varies due to the presence or not of controls (variables and groups) and peer review.
  4. Meta-analysis. When findings of several independent studies point in the same direction, your claim rests on a solid foundation.
  5. Mega-analysis. When meta-analyses say the same thing, this is as good as it gets. A good example is Hattie’s Visible Learning, which is a synthesis of 800 meta-analyses including 80 million students.

As a peak learner, assessing the validity of new data and current beliefs should become a reflex. Using the 5 levels of certainty presented here can be an excellent start.

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