Joined: Jan. 2006
I'm afraid I'm going to go a couple over the five-statement limit - sorry about that
1) We know that artificial selective pressures (with a few random mutations thrown in) can give rise to substantial changes in organisms (e.g. chihuahuas vs great danes).
2) We know that the various natural selective pressures can give rise to similar changes, albeit (usually) more slowly (e.g. finch beaks, moth colour schemes, etc).
3) We have a fossil record in which many quite radical transitions are documented in sufficient detail that the individual steps are quite obviously within the scope of the aformentioned selective pressures (e.g. mesonychids to whales).
4) We can even make and confirm non-trivial predictions based on the premise that life is limited to naturalistic evolutionary processes (e.g. the resemblance between one human chromosome and two chimp chromosomes, haemocyanin in stoneflies, Tiktaalik). In other words, it's extremely useful.
5) There is no direct scientific evidence for the presence of a Designer of any sort.
6) The premise that an unspecified intelligent designer did something unspecified at some unspecified point in the process (which is all that ID claims) hasn't given rise to any testable predictions whatsoever. In other words, it's bloody useless.
7) Hence, it's fairly sensible to affirm evolution as a useful scientific concept, and fairly daft to affirm Intelligent Design as a useful scientific concept.