At recent request, I’m just going to give a brief outline of my reasons why I don’t advocate ID. I’m not particularly anti-ID, and I am well aware that it has been unfairly maligned since the movement began. It is not creationism in disguise, and it is at least putatively scientific. That said, I do not advocate it. I have not thought or read in huge depth about it, so these are at best preliminary thoughts.
The first, boring answer is that I haven’t seen the logical argument spelled out anywhere. This is probably my own fault, and I should probably have made more of an effort, but the literature seems to focus very much on enormous improbabilities within evolution, which I don’t think tells us very much on its own. I’m aware that attempts have been made to solve this, and Dembski in particular has done some work on the logic of Intelligent Design. But I haven’t, so far, seen anything with concrete premises advanced, even once we’ve added in things like “specified” complexity. I am very open to someone providing an argument, though: feel free to comment!
But what I think is more difficult is that it doesn’t seem to make sense why God would bother fine tuning the universe to give parameters “necessary” for life if he had to carry on intervening to create life. Or, put another way, any parameters would be life-permitting if you had an omnipotent God prone to tinkering with molecules to aid abiogenesis.
Of course, this will be of no consequence to an ID proponent who doesn’t use the fine tuning argument for God, but most do, in my experience. And, in any case, I think fine tuning is much stronger – we can have more of an idea of possible comparison ranges for the values of constants, and we lack the probabilistic resources which are so abundant for the biological arguments (viz. multiverse and different planets, respectively). If one is making an argument that it is extremely unlikely that any planets would have the required conditions for life, then we seem to be making a fine tuning argument, not an argument from irreducible complexity (or whatever other datum is used as the explanans).
In terms of Bayes’ Theorem – which is the way I generally look at natural theology – my argument would be that I cannot identify any datum from the Intelligent Design movement which increases the probability of theism, once we have already put fine tuning into the equation. For something to constitute evidence for God, it must be such that P(E|T&k) > P(E|~T&k), where E is the evidence in question, T is theism, and k is our background information (which includes fine tuning). If ID proponents can suggest some E which satisfy this criterion – and can demonstrate that it does indeed satisfy this criterion – I will be very willing to hear.