They basically stopped short of calling the scientific method a cultural construct
I had this problem recently too, and my solution was to not mention "science" in and of itself, but mention heuristics based on probability. It's much harder to argue that math is a social construct. If you can explain how biases fail using probability theory it might go over a lot better.
I think speaking in terms of probabilities also clears up a lot of epistemological confusion. "Magical" thinkers tend to believe that a lack of absolute certainty is more or less equivalent to total uncertainty (I know I did). At the same time, they'll understand that a 50% chance is not a 99% chance even though neither of them is 100% certain. It might also be helpful to point out all the things they are intuitively very certain of (that the sun will rise, that the floor will not cave in, that the carrot they put in their mouth will taste like c...
I'm afraid I haven't properly designed the Muggles Studies course I introduced at my local Harry Potter fan club. Last Sunday we finally had our second class (after wasted months of insistence and delays), and I introduced some very basic descriptions of common biases, while of course emphasizing the need to detect them in ourselves before trying to detect them in other people. At some point, which I didn't completely notice, the discussion changed from an explanation of the attribution bias into a series of multicultural examples in favor of moral relativity. I honestly don't know how that happened, but as more and more attendants voiced their comments, I started to fear someone would irreversibly damage the lessons I was trying to teach. They basically stopped short of calling the scientific method a cultural construct, at which point I'm sure I would have snapped. I don't know what to make of this. Some part of me tries to encourage me and make me put more effort into showing these people the need for more reductionism in their worldview, but another part of me just wants to give them up as hopeless postmodernists. What should I do?