Best Laid Plans: Idealization and the Rationality–Accuracy Bridge

Abstract

Hilary Greaves and David Wallace argue that conditionalization maximizes expected accuracy and so is a rational requirement, but their argument presupposes a particular picture of the bridge between rationality and accuracy: the Best-Plan-to-Follow picture. And theorists such as Miriam Schoenfield and Robert Steel argue that it's possible to motivate an alternative picture-the Best-Plan-to-Make picture-that does not vindicate conditionalization. I show that these theorists are mistaken: it turns out that, if an update procedure maximizes expected accuracy on the Best-Plan-to-Follow picture, it's guaranteed to maximize expected accuracy on the Best-Plan-to-Make picture as well, in which case moving from the former to the latter can't help us avoid the conclusion that conditionalization is a rational requirement. If there's a problem with Greaves and Wallace's argument, it must lie elsewhere.

Higher-Order Evidence and the Dynamics of Self-Location: An Accuracy-Based Argument for Calibrationism

“…Part of my reason for adapting this argument is to show that, in fact, no recourse to Schoenfield’s nonstandard picture is necessary. (This is unsurprising given the argument in my ( 2021 ), the upshot of which is that Schoenfield’s picture and the standard picture always agree.)…”

“… 5 Schoenfield ( 2015 , 2018 ) introduces a nonstandard picture of the connection between expected accuracy and the rational status of update procedures and suggests that adopting this picture will allow us to “deliver an accuracy based argument for calibrating” ( 2018 , p. 711). But this, I argue in my ( 2021 ), is incorrect: Schoenfield’s alternative picture turns out always to agree with the standard picture about what update procedure is rational, and so, whatever other reasons there may be for adopting Schoenfield’s picture, doing so will be of no help in resolving the apparent incompatibility between calibrationism and the accuracy-first program. …”