What are the Best Hammers in the Rationalist Community?

I’ve toyed with the idea of giving an intro to rationality, hoping I can find the 20% of the material that provides 80% of the gains (or the 5% that provides 50% of the gains).

Here and there, I’ve also been asked what the rationality community is about, and I’ve struggled to give an effective summary. I usually say the 3 keys are seeing in terms of concepts rather than words (a la rationalist Taboo or hyperdimensional thingspace), fighting motivated reasoning (since most people are already strong enough to prove others wrong and just need to turn that force upon themselves), and correcting for the heuristics and biases. But are these really the top 3 most important pieces? Even if they are, what other Hammers would take 4th, 5th, and 6th place?

The Hammers and Nails post got me thinking again: What are the most powerful pieces of rationalist lore? If I had 1 day to tutor a brilliant, but untrained mind, what are the most powerful techniques that can most easily be taught?

The comments under Hammers and Nails are full of people saying what their favorite and most powerful techniques are, but I’d like to make an explicit invitation here to share. What are your hammers? (see https://​​www.lesserwrong.com/​​posts/​​QzBuuNEqJGQFeWM4f/​​hammers-and-nails)