The obvious answer is 'the sequences' but imo that is neither necessary nor sufficient. The Sequences are valuable but they are quite old at this point. They also run to over a million words (though Rationality AtZ is only ~600k). Here is a list of core skills and ideas:

1 - Rationality Techniques

Ideally, an experienced rationalist would have experience with most of the CFAR manual. Anyone trying to learn this material needs to actually try the techniques; theoretical knowledge is not enough. If I had to make a shorter list of techniques I would include:

Double Crux / Internal DC
Five-minute Timers
Trigger Action Plans
Bucket Errors
Goal/Aversion Factoring
Gears Level Understanding
Negative Visualisation / Murphy-Jitsu
Focusing

2 - AI Risk: Superintelligence

The rationality community was founded to help solve AI risk. Superintelligence gives an updated and complete version of the 'classic' argument for AI-risk. Superintelligence does not make as many strong claims about takeoff as Elizer's early writings. This seems useful given that positions closer to Paul Christiano's seem to be gaining prominence. I think the 'classic' arguments are still very much worth understanding. On the other hand, Superintelligence is ~125K words and not easy reading.

I think many readers can skip the first few chapters. The core argument is in chapters five through fourteen.

5. Decisive strategic advantage

6. Cognitive superpowers

7. The superintelligent will

8. Is the default outcome doom?

9. The control problem

10. Oracles, genies, sovereigns, tools

11. Multipolar scenarios

12. Acquiring values

13. Choosing the criteria for choosing

14. The strategic picture

3 - Cognitive Biases: Thinking Fast and Slow

Priming is the first research area discussed in depth in TF&S. Priming seems to be almost entirely BS. I would suggest skipping the chapter on priming and remembering the discussion of the 'hot hand fallacy' seems incorrect. Another potential downside is the length (~175K words). However, I don't think there is a better source overall. Many of the concepts in TF&S remain fundamental. The writing is also quite good and the historical value is extremely high. Here is a quick review from 2016.

4 - Statistics

It is hard to be an informed rationalist without a basic understanding of Bayesian thinking. You need to understand frequentist statistics to evaluate a lot of relev...

Miguel Ignacio Solano

Miguel Ignacio Solano