:D The proof for theory tends to be somewhat stable, by which I mean: 'the theory can be tested and produces results in line with what the theory predicts.'

If you are asking why one theory tends to be better than another is qualitative at best, but irrelevant quick. Once the two theories settled in people's brains, it only exacerbated the sell off. In a sense, the theories were irrelevant. Their impact, however, was not.

In other words, I think you have the entire structure all wrong. It is not binary at all. Or, at least, it does not require for it to be mutually exclusive.