Any time I hear a pro-bab y killer talk about it I ask if they have seen “The Silent Scream” - if they say no (And, as usally is the case, go ballistic) then I end the converstaion and tell them they are arguing from a position of ignorance.
I tell them to come back after they have seen it and I will gladly give them my undivided attention and listen to whatever they say.
Good approach.