The "what if" is for proving the concept. Proving concepts is great and all but they shouldn't be taken as concrete until applied in the real world. Sadly, until we can speed up time, observing species to species evolution will be nearly impossible. What we're left with is a hypothetical that is true based on what we can and have observed. We observe the little changes. We observe that these changes are hereditary and get passed on. We observe that the ones with benificial changes survive more easily. We can't find a barrier that prevents a species from changing when multiple changes are applied gradually. Add in the fossils that we find that show a gradual (albeit debatable) change and we come to the logical conclusion that species to species evolution is [b]possible[/b]. Make sense?