I think the argument towards evolution being a fact is that we have watched bacteria evolve in real time. (http://news.harvard.edu/gazette/story/2014/02/evoluti

I think the argument towards evolution being a fact is that we have watched bacteria evolve in real time. (http://news.harvard.edu/gazette/story/2014/02/evolution-in-real-time/ http://news.harvard.edu/gazette/story/2014/02/evolution-in-r...) So not only is it a good model, it happens to be elevated to the level of fact because we have directly observed it happening.