ellie!

Finally wrote this up after a conversation with @youzicha, who also helped throughout the whole writing process this past week.

In 2023 I began learning modal logic from a book recommended by @eka-mark, Graham Priest's "An Introduction to Non-Classical Logic", which also happens to be a very good introduction to classical logic. I was hoping to formalize the thoughts about decision theory I had been posting on Tumblr. I really liked the tableau method used in the book, which I now understand to be a formal system that sticks closely to Kripke semantics. In contrast to the natural deduction systems they use for modal logic on LessWrong, I was learning an algorithm, a decision procedure.

I thought MIRI's prisoner's dilemma tournament would be a good tutorial level to try out the technique. Instead, it felt more like a final boss, which was humbling.

But I recently stumbled across an Andrew Critch post that suggests a different modal agent for the tournament. When I tried the tableau technique I had practiced, it all just worked, and easily.

This post is the tutorial level I had hoped for, applying Kripke semantics to "modal combat". It's technical, but I think it's doable if you know what provability logic is and you've read the MIRI prisoner's dilemma paper.

Prescriptive philosophy of science('science should look like THIS') liberalism neoliberalism mainstream economics

thing I hate - coined by Hitler