Sorry about my last sentence in the previous post sounding dismissive, that was sloppy, and not representative of my views.

I guess my real issue with this is that I don't think that there's a 50% placebo, and disagree that the "declarative belief" does things directly. My anticipation of success or failure has an influence on my actions, but a 50% placebo I would imagine would work in real life based on hidden, unanticipated factors to the point that someone with accurate beliefs could say that "my anticipation contributes this much, X contributes this much, Y contributes this much, Z contributes this much, and given my x,y,z I anticipate this" and be pretty much correct.

In the least convenient possible universe, there seems to be enough hacks that rationality enables that I would reject the 50% placebo, and still net a win. I don't think we live in a universe where the majority of utility is behind 50% placebos.