'Tis remarkable how many disputes between would-be rationalists end in a game of reference class tennis. I suspect this is because our beliefs are partially driven by "intuition" (i.e. subcognitive black boxes giving us advice) (not that there's anything wrong with that), and when it comes time to try and share our intuition with other minds, we try to point to cases that "look similar", or the examples whereby our brain learned to pattern-recognize and judge "that sort" of case.

My own cached rule for such cases is to try and look inside the thing itself, rather than comparing it to other things - to drop into causal analysis, rather than trying to hit the ball back into your own preferred concept boundary of similar things. Focus on the object level, rather than the meta; and try to argue less by similarity, for the universe itself is not driven by Similarity and Contagion, after all.