To support his distinction between "guided Darwinism" and "unguided Darwinism" Alvin Plantinga refers to the eminent philosopher of biology, Elliot Sober, in his essay, "Evolution without Naturalism," ( in J. Kvanvig, ed., Oxford Studies in Philosophy of Religion, vol. 3). It's a fascinating essay, discussing not only the question of Darwinism and Theism, but also the question of Darwinism and Platonic Numbers.
On p. 196 of his essay, Sober writes:
"God can direct the evolutionary process in an ultimate sense, though mutations are undirected in a proximate sense. Biology says nothing about the former and theism says nothing about the latter."
This might be enough for Plantinga's guided Darwinism, if determinism is true. In a deterministic world, God could set up the initial conditions, and allow events to unfold, resulting in the precise path that He wanted evolution to follow.
However, what if the world is not deterministic? Could we still have "guided Darwinism?" And again, Sober is most obliging:
"Theistic evolutionists can of course be deists, holding that God starts the universe in motion and then forever after declines to intervene. But there is no contradiction in their embracing a more active God whose post-Creation interventions fly under the radar of evolutionary biology. Divine intervention isn't part of science, but the theory of evolution does not entail that none occurs.16
And in his footnote, Sober writes:
"Plantinga (2009) distinguishes "Darwinism" from "unguided Darwinism" and interprets the latter as incompatible with the existence of God. For Plantinga, Darwinism is a scientific theory whereas unguided Darwinism is that theory with a "metaphysical or theological add-on." I agree that the distinction is important, but think that the notion of unguidedness that is central to evolutionary biology is itself theologically neutral."
If I understand Sober's point, it is that Darwinian evolutionary theory claims that genetic mutations fall within a pattern that can be explained as random with respect to fitness. However, it is possible for God to cause some mutations that are not random with respect to fitness to occur, so long as they do not fall outside that apparently random pattern. Thus, they would "fly under the radar of evolutionary biology."
So then Darwinism, according to Sober, simply says that it looks like the mutations in evolution happened randomly with respect to fitness. The question of whether they actually did happen that way is outside of the purview of evolutionary biology.
So the popular view -- and my previous view -- that "guided Darwinism" is an oxymoron, is apparently incorrect.