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.
That isn't how I've heard it. E.g., Wikipedia: "The onyology [...] consists of a configuration [...] and a pilot wave." Bohm's book "The undivided universe" says (I'm going off the Amazon look-inside feature so it's possible that this would be invalidated by more context): "Let us now discuss this ontology in a more systematic way. Its key points are: [...] 2. This particle [sc. an electron -- gjm] is never separate from a new type of quantum field that fundamentally affects it." (The "new type of quantum field" is the wavefunction.) This seems to say in so many words that the wavefunction is as real as the particles in Bohmian mechanics, which seems to me enough to (e.g.) say that "observers" encoded therein are real.
Bohmian mechanics has developed quite a bit since Bohm. Its most significant contemporary defenders are Sheldon Goldstein, Nino Zanghi and Detlef Durr, and they advocate the ontology I described. See, for instance, this paper. From the abstract:
... (read more)