There are a spectrum of views, or cases, from Intelligent Design (of a “progressive creationist” sort) at one end — to Natural Selection at the other:
CASE 1) The Designer fiddles with genes of various creatures every once a while to produce an evolutionary-like progression of forms throughout geologic time.
Though there appear no necessary reasons why such fiddling must involve short steps rather than long ones, nor why it necessarily had to follow an evolutionary-like pattern of descent with modification over time as it certainly appears to. And questions remain whether individual creatures were fiddled with, or entire populations simultaneously; and also whether the Designer ensures that the creatures with the new genes survive and reproduce (more than those without the new genes), because if the reverse were true, even giving the creatures new genes would not ensure that those genes were passed along.
So the Designer in…
Case 1) apparently has to keep introducing new genetic changes in small increments over vast eons of time, restricts himself to always building on what came before, and also has to watch over individual creatures (and/or a population of them) to make sure they reproduce and pass along those new genetic changes he has made in their DNA.
Case 2) The Designer does not fiddle with the genes as in CASE 1) but allows them to mutate naturally over vast eons of time. But the Designer does ensure that specific mutations get passed along by making sure which creatures survive and reproduce, and/or which creatures die. In this case no direct fiddling with genes is necessary, just a fiddling with which creatures survive and breed to pass along particular mutations that the Designer deems appropriate to pass on, and perhaps the Designer also stops some creatures from breeding, the ones with the old mutations.
Case 3) The Designer sets up nature “in the beginning” such that mutations continue to occur naturally, and creatures produce lots of offspring, but only a fraction of them survive and breed and thus pass along their genes to the rest of the population. In this case their survival depends on natural circumstances, not a supernatural picking and choosing of which creatures survive and which do not.
The third option above is modern day “neo-Darwinism,” which need not exclude a Designer, just a Designer that allows nature to do her own job — via a cosmos created “in the beginning.” (When I consider the three options above, I must admit, creating something that can itself create other things, is the most impressive of the three options, at least to my mind. I mean, pulling a rabbit out of a hat every now and then may be impressive, but having to keep pulling tiny rabbits out of hats for a billion years seems too “labor intensive” — and doesnʼt seem as impressive to me as creating the element known as carbon with the inherent properties such that it can evolve in billions of years into a human being all on its own.)
Notice that option 1) involves a Designer “fiddling” by introducing specific point mutations in a gene, or instantaneously adding new genes or new chromosomes, such that even if a scientist was there watching it happen (watching those genetic changes underneath a microscope of a cell that was still living and attached to the organism in question) such first-hand observation could tell that scientist nothing about the nature, or causal reason, or the “science” behind what had just happened, except that it was an apparent miracle.
It would also be a miracle in the case of option 2)in which the Designer miraculously fiddles with the destiny of particular organisms, miraculously choosing which survive and reproduce and which die (in order to ensure that specific mutations “out-compete” other mutations in nature).
Another point I would make is that there is nothing particularly “scientific” about watching something pop miraculously into existence, or watching one creature rather than another survive in a totally miraculous fashion (so it could reproduce and leave more offspring).
To use the “rabbit out of the hat” illustration again, if I knew a magician who performed genuine magic (instead of carefully orchestrated “tricks”), and I watched him pull a rabbit totally miraculously out of the air inside his hat, that would teach me nothing, certainly nothing scientific about either hats or rabbits or about any genuine connection between the two. It would only prove to me that I had witnessed a “performance.” But as a scientist qua scientist, I would still want to know how the trick was done. By what “means” was a rabbit produced from the inside of that hat? Even if the means were miraculous, a scientist would want to find out what the exact ways and means of performing that particular miracle were. In the case of a Designer designing creatures over geologic time a scientist qua scientist would be dying to find out more about how it was done and why in that particular way and what thoughts were going through Godʼs mind at each moment. In other words, a scientist qua scientist would not be satisfied that “it just happened,” but remain curious about how it happened, what steps there were leading up and through the process, what connected with what, and why they connected.
And since we cannot know such things in cases 1) or 2) above, since the ways and means are deemed absolute miracles, I think it quite appropriate of “scientists qua scientists” to continue to investigate the matter from the practical perspective of 3).
Even as a creationist I used to wonder why God ever bothered to create creatures like chimps and apes, that were more similar to human beings than any other creatures in both looks and behaviors, mockingly so, intriguingly so. And then when I later discovered that there were other primates in the geological past, that even creationists could no longer explain their remains away as “random bones,” such as Homo Erectus (not a hoax from China, but found in Africa too!), I began to question my creationist beliefs.