The Under-Determination of a Theory by Data

There are two alternatives for explanations, both of which fit the observable facts and theories we have around those. But in most cases it's possible to figure out some prediction that's made by one of the theories and not by the other. The wave theory predicts that you'll observe certain interference phenomena in certain situations - but particle theory doesn't have any natural explanation of that. When we try it, we find interference patterns. Particle theory is out and the wave theory wins.