Really, I wish anyone who wants to prattle on and on about the deficiencies of Darwinism would take, at the very least, undergraduate courses on the theory of computation and artificial intelligence. It would save a lot of electrons being wasted the way Barham does.
It starts badly, with a claim that the "Darwinian consensus" (whatever that means) is "gradual[ly] crumbling" and that the "official explanation" (no kidding -- like a 9/11 truther, he really says that) "of the nature of living things---and therefore of human beings---that we've all been led to believe in for the past 60 or 70 years turns out to be dead wrong in some essential respects."
Yeah, yeah. We've heard that for more than a hundred years; it's what Glenn Morton called the "longest-running falsehood in creationism".
"The machine metaphor was a mistake---organisms are not machines, they are intelligent agents."
This is precisely the kind of silliness that a good course on the theory of computation could avoid. Why does he think that a machine cannot be an "intelligent agent"?
"For one thing, it [Darwinism] meant that all purpose is an illusion, even in ourselves, which is absurd. We know that is not true from the direct evidence of our own experience."
No, the biological theory of evolution does not mean that "all purpose is an illusion". Trouble results from using the vague word "purpose", which means many things to different people. It is not a concept that has a precise scientific definition (what are the units of "purpose"?), although Barham tries to provide one: he says, "Purpose is the idea that something happens, not because it must tout court, according to physical law, but rather because it must conditionally, in order for something else to happen." Well, that's not what most people mean by purpose, but even so, practically any computer program would exhibit purpose under Barham's definition. And nature is filled with objects that can serve as a basis for computation, including DNA and sandpiles. There is simply no logical barrier at all to computing devices arising through natural processes.
There are a few philosophers who have something interesting to say about evolution, but Barham is not one of them.