Therefore they must not vary all that much in terms of metabolism.
I don't think that follows, or at least not without a lot of other explanation, even if you grant that temperature doesn't vary in any significant way between people (which I'm not sure I do). The body has multiple mechanisms for maintaining temperature, of which metabolic rate is only one. It seems entirely plausible to me that people run their metabolisms at different rates and adjust their peripheral vasodilation and sweating rate to balance it all out near 37 C/98 F. Core temperature might vary between people by only a few degrees, but surface temperature varies much more widely.
Core temperature might vary between people by only a few degrees, but surface temperature varies much more widely.
That's an interesting point. Would you agree that if a person has a higher metabolism, one would expect that under your theory, their skin temperature would be expected to be higher?
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.