If a theory is mathematically elegant, I would consider that evidence for the theory. For example, the ability to explain the exact gauge groups and representa

If a theory is mathematically elegant, I would consider that evidence for the theory. For example, the ability to explain the exact gauge groups and representations that comprise the Standard Model, or the masses of the elementary particles. In fact, I would say that a theory that could do this would be "tested" because it is a historical accident that we discovered the gauge groups/masses before the theory. As far as I understand it, string theory once promised to do precisely this. String theory was considered promising because it had no vertex factors in its Feynman diagram. Because there were only strings, you only needed to know the free space propagator for a patch of string. However, as I understand it, string theory then turned out to be have more possible parameters, and this original promise was lost. The kind of elegance that the author seems to be talking about is conceptual elegance, and I also reject this as evidence. For example, invoking the anthropic principal plus multiple universes to explain the parameters of the Standard Model. To me this is no more compelling than the Christian "grand unified theory" that unifies ethics, numinous awe, and the existence of the universe.