Theists and their Straw Men, Life and its Beauty.

So, back to the Hitchens critique of Darwinism. (1) (2) By the way, I acknowledge that the piece I have picked up on is not his own words, but someone else's attempt to sum up his views. However, the "Hitchens critique" seems reasonable shorthand, given that the piece is explicitly associated with him, even if it does not necessarily derive from him. You can find some comment about this in words that are explicitly his under "What are Archbishops for?"; scroll down the page to find it. He says there:
"Darwin's theory - and that of his followers - is a heroic and impressive attempt to describe events that no human could ever have witnessed, on the basis of very thin evidence which cannot easily be tested."

But I shall go back to the original piece first, because there's even more foolishness in it. Like this: "the theory of evolution, unlike other scientific theories cannot be tested because it cannot be and has not been observed, and remains a theory about the distant past." See that Big Bang? Apparently, that's not a scientific theory. To be fair, this is where poor wording may be making Hitchens look more ignorant of science than he actually is. Or maybe he really does believe that the theory of evolution is unique in this regard.

But what, exactly, is meant by "cannot be tested"? This seems to assume that unless you can reproduce all of what you're talking about in a laboratory experiment, then you can't be doing science. Because there are plenty of ways to test a theory. For example, you could dig up thousands upon thousands of fossils which demonstrate different species living on the earth at different times. Or you could look for "transitional stages". Good one this, because for some reason, anti-darwinists of various stripes often point to it:

"If all that's true, then we should see lots of inbetween stages, shouldn't we." Yes, is the reply, and the thing is, that we do. For example, every animal that has ever lived anywhere ever. And all the plants, too. "Species" only appear to be discrete entities because what we actually see are individual creatures at one moment in time. But if that's too abstract to grasp, then take the eye. (Squelch.) Go for a more complex one, such as that of a human, or octopus. Now, the fantastic thing is that just about every stage that could be easily imagined in between "no eye at all" and the organ in your hand exists in animals, many of them alive now. (This eye bit is entirely derived from The Blind Watchmaker, by the way.) So that's transitional stages thoroughly sorted out, then.

Or there's the burgeoning science of genetics, and all that we have learned about molecular clocks. The test, not to labour the point, is whether the information that we keep on turning up is compatible with the theory, or not. And it is, in all its vast quantity.

So, and lastly for today, about this "has not been observed bit". I hope I've already indicated that a theory can be highly robust without needing for all its implications to be seen in process. But go back to the bit about natural selection. The two observations, I would contend, being observations, have been observed. Stop me if I've missed something, here. The rest simply follows. The really interesting part, though, is speciation, the process itself. Even if species, as such, only exist in snapshots of time, the process of speciation is absolutely vital; it does not (necessarily) happen in quantum leaps, but even if we cannot draw a boundary, it is still possible to say "this species is not that species, yet they are both descended from that species." If you can identify that, then you have identified a speciation.
Shame we can't see that happening, isn't it? Oh. Have a look here. And here. I'll not deny that this evidence has its detractors. Some of those detractors may actually be better at it than that one, who nicely attempts to refute the evidence by ignoring most of it (compare the examples listed by the proponent above and the opponent), and by setting up straw men: "Darwinists say all dogs are different species!". Only thick ones. "Speciation...In the sense of one species changing into another" is not what we're looking for; speciation, where descendents of a common ancestor diverge into separate species is another matter entirely.

Well, I'm off for now. If this has become gibberish, I may well come back to tighten it up; in the meantime, I just wish we Darwinists had more than just the flimsiest of evidence to draw upon. More about why Intelligent Design is just a misprint of Nonrational Craving for a big old Daddy in the sky later.