I can't dispute the instrumental value of a rational approach to building airplanes. But the instrumental value of a rational approach to religion is less clear to me.
It is difficult to estimate the instrumental value of anything when terminal values are unknown/unspecified. If one starts with absolute certainly that a particular religion is true, then rationality may have little instrumental value with regards to religion for that person (except to help them realize that absolute certainty is problematic). On the other hand, if one is deciding whether to join or leave a religion, then epistemic rationality would likely be extremely useful in making the right choice.
Today's post, Why truth? And... was originally published on 27 November 2006. A summary (taken from the LW wiki):
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This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was The Martial Art of Rationality, and you can use the sequence_reruns tag or rss feed to follow the rest of the series.
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