Technically, evolution is an observed fact. Evolution by means of natural selection is the scientific theory...
Presently, evolution is shorthand for both the class of accepted theories that forms the modern synthesis or evolutionary synthesis (terms used most frequently in evolutionary biology literature ). It is also an observed fact in all its particulars. Universal common descent, on the other hand, marries evolutionary synthesis with cladistics, paleontology, geology and some other stuff to come up with a set of unobserved facts. As I understand it, this is where what passes for serious debate between pro and anti-"evolution" partisans.
A word on "theory." It's accurate or useful to argue that the term has a special meaning in science that it lacks elsewhere. The term in law, philosophy, mathematics and even colloquial use refers to an set of inferences that merits confidence based on how well it fits the evidence both in hand and subsequently uncovered (prediction). The only difference is the standard of proof thought to verify or defeat an idea.
Last edited by a moderator: