In response to a claim that creationism and ID are unfalsifiable and therefore “not science”, I left the below comment. I though I would post it here as well:
The Designer is not falsifiable per se (I’ll agree). However, creationism makes falsifiable claims. There is more to creationism than “God created the heavens and earth.” When you say that creationism is “not falsifiable”, it comes off (on my end) as a blanket statement. I see it all the time. “Creationism is not falsifiable” on the one hand, but on the other “creationism is demonstrably false” It sounds schizophrenic (CS is simultaneously unfalsifiable and falsified).
Creationism is filled with assumptions that can be tested. However, on both sides of the fence, there are theories that are abstract; they are general concepts that by no means be tested directly. Moreover, only predictions about the physical world which can be drawn from the theory can actually be subjected to test or experimentation. This puts God out of the field of testability and thus He is un-falsifiable in relation to direct scientific detection.
Another thing is that falsification seems to be inappropriately used as this transcendent line of demarcation. However, scientific theories are typically integrated into a much larger framework of presuppositions (via philosophical) and assumptions that not only entice conclusions, but ultimate characteristics of any given theory.
Evolution has its issues as well. When all else fails, evolutionist appeal to the unknown, and even unknowable naturalistic causes that science has not yet discovered, and in reality may never discover.
However, if I may note, saying that creationism is “not science” is used as more of a type of ad hom toward creationism and a semantic smokescreen that tends to demote it’s merits before even engaging the issue. It’s a sneaky way to poison the well. In addition, if creationism can't be falsified, then no possible fact or event could count as evidence against creationism. It would follow, then, that Darwinian evolution does not falsify creationism. However, they make contradictory claims.
Take for example Intelligent Design Theory. ID theorists propose that some features of biological organisms are irreducibly complex; Darwinists (in the complete naturalistic sense), however, deny that any are irreducibly complex. Ipso facto, this contradistinction alone denotes that ID theory can be falsifiable by showing X biological organism are not irreducibly complex. Darwinists contend that there are no irreducibly complex organisms and thus ID’s claim is false. However, if that claim is false, then it is falsifiable; therefore, if ID theorists propose what is possibly a false claim, it is open to falsification. Thus, evidence for Darwinism is evidence against creationism and ID theory and evidence for creation or ID theory is evidence against Darwinism.
We have falsifiable propositions either way, thus, we have theories that are open to falsification.