It may eventually turn out that there is something about nervous systems that is uniquely suited for the mediation of intelligence (Searle 1980), but until that “something” is identified, the objection seems both vitalistic and anthropocentric. Meanwhile, my bet is that some suite of information-processing, adaptation-developing, and adaptation- implementing features will prove necessary and sufficient for the implementation of intelligence, regardless of the material which instantiates them. The extent to which that suite includes the features I have attributed to species remains to be seen.Which does seem to explicitly exclude the idea that intelligence actually is evolution and that they are really two sides of the same coin, while in other ways arguing that we can see some deep homologies between species evolution and organism intelligence.
It all turns out to be a pretty dry read although Sharlow's paper is great and certainly does explain the real flaw in design. Which is actually the explanation I agree with. There is real design in nature, and nature is entirely sufficient to result in said design. The primary flaw is the implicit assumption that if a system is designed then it cannot be self-designed. To wit, he gives a notable example of a self-designing system: the human brain. As it is entirely possible to without external input, derive a new splendid mathematical proof or other insight due to the functioning of the brain. So the brain must, in some ways, be seen to be able to redesign itself to be more designed. That self-design is possible is the principle flaw in the argument from design. When we conclude that the designs of nature are like the designs of human ingenuity, we should rather conclude that these designs are created by the system themselves (probably through a form of evolution) rather than subjected to an infinite regress of skyhooks.
There is real design in nature. Design requires a designer. That designer is nature through the self-designing process of evolution.
Most evolutionary attacks on the argument from design suppose that because it's possible for evolution to produce results that seem like design then therefore there must not be any real design in nature. But, that really does narrow the use of design rather strongly. After all, Venter recently designed a lifeform is that life form designed? Well yes. But, he cheated and used all well evolved genes. It really is a pretty silly line and if humans invented squirrels they would be considered designed.
There's a lot of philosophical arguments kicking around but they just don't go far enough in my mind.