I feel uneasy when someone suggests that people should (for practice or whatever) argue for something that they don't believe. If you can argue for anything your words mean nothing.
Well, startng from vastly different priors and interpreting the evidence according to the intermediate posterior probabilities at the moment of evaluation could reasonably lead to different conclusions. Especially in the areas where controlled experiments are hard to do, and so the evidence may be relatively weak.
From Julian Sanchez, a brilliant idea unlikely to be implemented: