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.
The Bohmian stance is that the "pilot wave" isn't a real thing, it's a mathematical tool. The stuff that actually exists in the universe is the particles. The pilot wave is just a construct we use to predict how the particles move. So it's a little misleading to say that the particles are epiphenomenal. Ordinarily, when we say that X is epiphenomenal in some theory, we mean that X is causally affected by all the other stuff in the universe but does not itself have any causal effect on any other stuff. The Bohmian position is that there is no other stuff in the universe besides the particles, so it doesn't make really sense to say the particles are epiphenomenal.
Similarly, saying that all observers will find themselves somewhere in the pilot wave is also a bit misleading. It's true that there are mathematical structures within the pilot wave (including in those parts of it that do not carry particles) that correspond to observers. However, since the pilot wave isn't a real thing, those observers don't actually exist. The only observers that exist are the ones made out of particles.
MWI, on the other hand, interprets the wave function as representing a real physical object, so any structures within the wave function correspond to stuff that actually exists in the universe.
As a pragmatist, how do you decide if something is or isn't real?