ETA: see below.
Some interesting thoughts on the so-called "onus [or burden] of proof" are out
on the web right now, and I wanted to make a few comments, if I may:
I agree the "burden of proof" concept is maybe overstated in humanistic disciplines like religious studies. I'd also agree that in areas without a consensus position, the burden is indeed simply on the person trying to make one case or another. Having said that, I think there are meaningful ways in which a "burden of proof" can be employed.