Darwins theory meets that criteria.
Proponents of intelligent design have yet to develop a testable hypothesis that could get it into the scientific arena.
The only argument Ive ever heard from intelligent designers
has to do with their incredulity about mechanisms behind evolution.
Their stance is that the irreducible complexity of life must have had a
designer. Ive spoken with proponents of intelligent design, and Ive
read their writings. The only thing they have to say is that they accept
the reality of microevolution, as they must if they believe in things
like flu shots, but they do not see how one species might develop from
I feel a
certain sympathy with that view. There is clearly intelligence at work
in nature that is well beyond human comprehension. Im not uncomfortable
with the naming of that intelligence as God, but I would hesitate to be
so specific as to say that it is God as described in the Bible. That is
the rather huge leap of faith that proponents of intelligent design are
asking that we make in science classes. It is not science.