What if you are trying to explain evolution to someone and he states "Evolution is just another religion." Is that a stop sign? To me it is, in the sense that the only reason to continue at that point would be to enjoy the sound of your own voice. The person has just signalled his membership in a tribe; you recognize that you are not in that tribe; and you recognize that he will not consider anything further you have to say on the subject, because that would be disloyal to the tribe. Global warming is a religion, taxation is theft, property is theft, healthcare is not a right (I'm not sure if the reverse is used as a flag, too), there is no peace without justice, "allopathic medicine"; there are a lot of them. I'm old enough to remember "The Soviet Union is a state in transition," too. (Sadly, it was in transition to total collapse.) All these statements are what Eliezer calls "Green and Blue" (I think--those are the two chariot racing team colors, right?) markers. I'm not sure if these statements are also semantic stop signs. Anyway, I think that class of statement is very different than statements like abiogenesis or prebiotic soup, because the latter statements indicate that the original topic has been exhausted. That line of reasoning has gone to its logical end, and to continue conversing, we must switch to a different discussion. Not quite the same thing as saying that "tribal loyalty dictates that I do not use reason to consider anything further you say on this subject."