Thinking Complete

Note: after putting this online, I noticed several problems with my original framing of the arguments. While I don't think they invalidated the overall conclusion, they did (ironically enough) make the post much less coherent. The version below has been significantly edited in an attempt to alleviate these issues. Rohin Shah has recently criticised Eliezer’s argument that “ sufficiently optimised agents appear coherent ”, on the grounds that any behaviour can be rationalised as maximisation of the expectation of some utility function. In this post I dig deeper into this disagreement, concluding that Rohin is broadly correct, although the issue is more complex than he makes it out to be. Here’s Eliezer’s summary of his original argument: Violations of coherence constraints in probability theory and decision theory correspond to qualitatively destructive or dominated behaviors. Coherence violations so easily computed as to be humanly predictable should be eliminated by optimi

Epistemic status: I endorse the core intuitions behind this post, but am only moderately confident in the specific claims made. Also, while I do have a degree in philosophy, I am not a professional ethicist, and I’d appreciate feedback on how these ideas relate to existing literature. (Edited to add: readers have pointed out similarities to moral particularism and pluralism; the concept of incomparability also seems relevant). Moral indefinability is the term I use for the idea that there is no ethical theory which provides acceptable solutions to all moral dilemmas, and which also has the theoretical virtues (such as simplicity, precision and non-arbitrariness) that we currently desire. I think this is an important and true perspective on ethics, and in this post will explain why I hold it, with the caveat that I'm focusing more on airing these ideas than constructing a watertight argument. Here’s another way of explaining moral indefinability: let’s think of ethical theories