Evidence of Intent

Your strength as a rationalist is your ability to be more confused by fiction than by reality.  If you are equally good at explaining any outcome, you have zero knowledge.

— Eliezer

Logic is equally valid in all universes, and hence cannot tell you which of those universes you are in. Applying logic does not give you new information, it merely aligns your decisions better to the information you already have, by either reducing bias or increasing the efficiency of your estimators.

It is good to distinguish when you are getting new information and when you are processing existing information better, because knowing explicitly how the validity of your ideas flows allows you to make corrections faster and easier.

Long tails in distributions are troublesome for 2 reasons:

1. They are hard to test for empirically because they represent rare events. How they look like in any given model is more model-driven than data-driven.
2. Models which are modular, and construct the distribution of interest from many independent component distributions, tend to underestimate long tails in the distribution of interest. This is a problem of degree, not a black and white issue – theoretical proofs use absolutely independent component distributions, and using those proofs for real work requires an assessment of whether components are independent enough in reality. That assessment is non-trivial and all too often skipped.

1. Forcing a concession
2. Convincing the other person
3. Maximally updating your own beliefs