The key claim is: You can’t evaluate which beliefs and decision theory to endorse just by asking “which ones perform the best?” Because the whole question is what it means to systematically perform better, under uncertainty. Every operationalization of “systematically performing better” we’re aware of is either:
Incomplete — like “avoiding dominated strategies”, which leaves a lot unconstrained;
A poorly motivated proxy for the performance we actually care about — like “doing what’s worked in the past”; or
Secretly smuggling in nontrivial non-pragmatic assumptions — like “doing what’s worked in the past, not because that’s what we actually care about, but because past performance predicts future performance”
This is what we meant to convey with this sentence: “On any way of making sense of those words, we end up either calling a very wide range of beliefs and decisions “rational”, or reifying an objective that has nothing to do with our terminal goals without some substantive assumptions.”
(I can’t tell from your comment if you agree with all of that. But, if this was all obvious to you, great! But we’ve often had discussions where someone appealed to “which ones perform the best?” in a way that misses these points.)
The key claim is: You can’t evaluate which beliefs and decision theory to endorse just by asking “which ones perform the best?” Because the whole question is what it means to systematically perform better, under uncertainty. Every operationalization of “systematically performing better” we’re aware of is either:
Incomplete — like “avoiding dominated strategies”, which leaves a lot unconstrained;
A poorly motivated proxy for the performance we actually care about — like “doing what’s worked in the past”; or
Secretly smuggling in nontrivial non-pragmatic assumptions — like “doing what’s worked in the past, not because that’s what we actually care about, but because past performance predicts future performance”
This is what we meant to convey with this sentence: “On any way of making sense of those words, we end up either calling a very wide range of beliefs and decisions “rational”, or reifying an objective that has nothing to do with our terminal goals without some substantive assumptions.”
(I can’t tell from your comment if you agree with all of that. But, if this was all obvious to you, great! But we’ve often had discussions where someone appealed to “which ones perform the best?” in a way that misses these points.)