As a pragmatist, how do you decide if something is or isn't real?
My stance is that whether or not an entity is real is not a meta-level philosophical question, the way it is usually treated in the realism vs. anti-realism debates, but an object-level scientific question. Our scientific theories, interpreted literally, are committed to certain ontologies. MWI is quite clearly committed to the existence of something like a universal wave function, otherwise none of its explanations or purported merits make any sense. I also think (like David Wallace) that basic quantum theory, interpreted literally and without any ontolog...
What is something you used to believe, preferably something concrete with direct or implied predictions, that you now know was dead wrong. Was your belief rational given what you knew and could know back then, or was it irrational, and why?
Edit: I feel like some of these are getting a bit glib and political. Please try to explain what false assumptions or biases were underlying your beliefs - be introspective - this is LW after all.