What is Meant by Evolution?

In Scientific Literacy and the Myth of the Scientific Method, Henry H. Bauer asks the following questions about evolution:

When evolution is said to be a fact, not a theory, what is actually meant? That now-living things have descended from ancestors, with modification, over time? Or that the modifications came by chance, not by design? Or, in addition, that all living things ultimately had the same ancestor? Or, still further, that the "first living thing" had as its ancestor a nonliving thing? Context indicates that when evolution is asserted to be a fact, not a theory, the view actually being pushed includes that of common origin, ultimate inorganic ancestry, and modification through nonpurposive mechanisms: a set of beliefs that goes far beyond the mountain of fact that is actually there, which consists largely of fossils that demonstrate some sort of change over time.

The above paragraph is a direct quote from his book. I would add only that this illustrates how a particular philosophical position can lead scientists to make unsupported conclusions.