[tripzilch]

Yeah it's called "The Barstool Experiment". Look it up :-)

The short summary is: Two people sitting in a bar, discussing how there is no objective truth, or that "science or truth exists only at the whims of the social order" and stuff like that, all day long. And then a third person comes along and smashes their brains with a barstool. In some variations, the first two people are a scientist and a priest. But the third person is just some dude with a barstool.