To Mr. Unicorn:
The analogy was flawed because of this reason: The claim is that supposedly intelligent life could not have arisen by blind chance. The popular form of this argument is Hoyle's argument that evolution states that if you threw the parts of a 747 jet airliner into a tornado, eventually you'd get a completed aircraft. ID advocates then say: "either it's this sort of blind chance, or it's God." Clearly the logical choice in that scenario is God.
But it misrepresents natural selection by a wide margin. Let's take the same 747, and put its parts into different stipulations, ones that mirror evolution. One small part randomly mixes with the rest until it locks together with an adjacent part. This is more cohesive than 1 part, so it stays together. In biology this would be analogous to small adaptations in successive generations of species through genetic mutation that allow an organism to better adapt to its surroundings.
So mix that 2-link chain in the tornado for a few more years, and it's bound to link up with 1-2 more parts (among thousands, I'm assuming). This continues. So we have an completed 747 in just a few thousand years if we assume, say, one match per year. Evolution is working with hundreds of millions of years, so the small adaptations lead to large-scale change.
In Hoyle's scenario (or your clock scenario), the 747 would need to be completed all at once in order for evolution to be correct. But that's not how natural selection works, which is by incremental change over countless generations. Only small things are accomplished at any one time, but the system keeps positive changes. Let's look at it another way:
The famous monkeys typing Shakespeare. Put a thousand monkeys in a room with typewriters for a year. None of them will write Shakespeare (any play will do). But let's say each correct letter is kept, then we move on to the next one (much more akin to how natural selection works). I would venture to say every minute or so we'd have a correct letter (there are only 26 to choose from), so we'd have Shakespeare in probably a few weeks.
So for the earliest stages of evolution to have worked, all that would be needed is simple protein chains that could break down nutrients better (or something similarly mundane). The complexity we see is the result of millions of years of such change.
That's natural selection in a nutshell. I hope it helps.
ID advocates are great at trying to attack evolution. Usually they misrepresent evolution, so they are just plain false. And even if they have valid points about evolution (I have yet to see any worth merit) they fail to recognize that discrediting part of an idea doesn't make the whole thing false...all the evidence that has ever been collected points to evolution being a fact, so even if scientists get one thing wrong, the whole remains intact. And second, disproving one theory (as yet unaccomplished) doesn't automatically make their theory correct, especially when no evidence supports ID.
ID advocates, to have any credibility, would need to first explain how God intervenes in evolution that would give their theory merit, how we are to test for such intervention, and what evidence exists that points to God having intervened in human development. So far, none exists, and the little that does is either bad science or wild speculation, or the aforementioned attacking of evolution (which does nothing to support their theory).