The promised follow-up to A New (Bad) Argument: I'm discovering that I have quite a lot to say about this, and since I want to approach what Perry Marshall has said in the most philosophically rigorous way possible (at least given the medium), this post is going to be broken into multiple parts. Marshall calls his talk "If You Can Read This, I Can Prove God Exists," and the title is (obviously) a take off on that. Once again, I urge you to go read and/or listen to the talk before continuing on here--while I will explain Marshall's argument as much as necessary, he should be able to represent his own ideas himself. Before I begin my critique, I'd like to commend Marshall on a very clever and (as far as I know) original argument; it isn't often that I see a purely philosophical (i.e. non-Biblical) case for Intelligent Design, and creativity in argumentation (even when the arguer is wrong) ought to be commended. Unfortunately for Marshall, it seems to me that he has only a shallow understanding of philosophy of mind and philosophy of language (not to mention computational linguistics, evolutionary biology, and molecular biology), and many of his problems arise from this shallow understanding. I'm going to do my best to point out precisely where I think he goes wrong, and to offer at least a sketch of my own theory of meaning/representation in the process.
Marshall is arguing primarily (by his own admission) against a naturalistic worldview, so let's start by defining just what that means. A naturalistic account (contrast with a supernaturalistic account) is one that seeks to explain phenomena in natural (if not materialistic) terms. It is worth emphasizing that materialism and naturalism are not necessarily synonymous--I hold exclusively naturalistic views, but I would be somewhat hesitant to call myself a materialist, simply because of some of the dogma that tends to surround the term (e.g. that the mind "just is" the brain). For the sake of discussion, let's just define "naturalism" as "any worldview that explicitly affirms that any factor F that plays a causal role in any system S is ultimately causally reducible to a natural (i.e. describable by physics) phenomenon. Thus, a naturalistic account of (say) color perception (heh) would describe color perception purely in terms of natural (again, for lack of a better synonym let's say by natural we mean "physical") processes. This isn't exactly right (in my opinion), but it is close enough for our current discussion. For a slightly more lengthy account, see metaphysical naturalism. I'm sure Eripsa will howl about any oversights I've made.
It's important to contrast this (naturalism) to the worldview that Marshall is trying to advance; while he never explicitly (as far as I can remember) describes his account as "supernaturalism," that is in fact what he is advancing; he wants to articulate a worldview in which the physical universe is not causally closed; in other words, physical reality can be influenced by ghosts, spirits, souls, and non-physical deities. Strike one, Mr. Marshall.
At its heart, Marshall's argument for the claim that life must have been designed is a psycho-linguistic one; he's arguing for his claim on the basis of the way symbols (e.g. the little marks on the screen in front of you) acquire meaning. It should be obvious to most people that the series of pixels "the cat is on the mat" has absolutely no intrinsic meaning--that is, there's nothing physical about that particular arrangement of pixels that makes it have anything to do with cats, mats, or the relationship between the two. It is only by virtue of the fact that we (i.e. humans) have minds with intentionality (in other words, minds with the ability to have states like beliefs and desires which are "about" something) that purely physical symbols come to represent something. Marshall gets this right.
It occurs to me that I should probably say a few words about intentionality, since it's a concept that is inevitably going to come up over and over again in this discussion (not to mention a pretty confusing idea). First, forget everything you know about the English word "intention;" the word "intentionality" comes from a Latin root that is (for the most part) unrelated to the modern-day colloquial meaning of "intention" or "intentional." In short, the philosophical meaning of "intentionality" is "the property of having aboutness or directedness." The paradigmatic examples of so-called "intentional states" are beliefs and desires; these examples were not chosen randomly, and it is pretty easy to see what is meant by "aboutness" or "directedness" when you consider these two terms. Both beliefs and desires must have objects--it doesn't make sense to say "I believe" or "I desire." I must, in other words, always desire something or believe something (similarly with considering, wondering, hoping, fearing, etc.). It is worth mentioning that not all mental states are necessarily intentional: anxiety, for example, does not necessarily require an object--I can be anxious without being anxious about something.
Of course this is a very rough sketch of a complex concept, and is greatly simplified; again, however, it should be sufficient for our discussion of Marshall's work. If you're interested in more about this very deep concept, I'd recommend this book by John Searle.
This concept is significantly more powerful than it may first appear, as it is essential in our capacity to represent--to create symbols, in other words. Symbols (e.g. 'the cat is on the mat') are only symbols if they represent (i.e. are about) something other than themselves. Thus, the concept of intentionality is central in Marshall's thesis.
Whew, I think that's enough for starters; more to come tomorrow.