from:
http://www.beyondveg.com/nicholson-w/evo-creation/evo-vs-creation1b.shtml#se
ction%205

"From Stephen Jay Gould:


In the American vernacular, "theory" often means "imperfect fact"--part of a
hierarchy of confidence running downhill from fact to theory to hypothesis
to guess. Thus the power of the creationist argument: evolution is "only" a
theory and intense debate now rages about many aspects of the theory. If
evolution is worse than a fact, and scientists can't even make up their
minds about the theory, then what confidence can we have in it?...

Well evolution is a theory. It is also a fact. And facts and theories are
different things, not rungs in a hierarchy of increasing certainty. Facts
are the world's data. Theories are structures of ideas that explain and
interpret facts. Facts don't go away when scientists debate rival theories
to explain them. Einstein's theory of gravitation replaced Newton's in this
century, but apples didn't suspend themselves in midair, pending the
outcome. And humans evolved from ape-like ancestors whether they did so by
Darwin's proposed mechanism or by some other yet to be discovered. Moreover,
"fact" doesn't mean "absolute certainty"; there ain't no such animal in an
exciting and complex world. The final proofs of logic and mathematics flow
deductively from stated premises and achieve certainty only because they are
NOT about the empirical world. Evolutionists make no claim for perpetual
truth, though creationists often do (and then attack us falsely for a style
of argument that they themselves favor). In science "fact" can only mean
"confirmed to such a degree that it would be perverse to withhold
provisional consent." I suppose that apples might start to rise tomorrow,
but the possibility does not merit equal time in physics classrooms.
Evolutionists have been very clear about this distinction of fact and theory
from the very beginning, if only because we have always acknowledged how far
we are from completely understanding the mechanisms (theory) by which evolut
ion (fact) occurred...

--Stephen J. Gould, "Evolution as Fact and Theory"; Discover, May 1981"