But I think Seth may be right.
He says that the Intelligent Design assertion fails, not because that something looks designed shouldn't be taken as evidence that it is designed, but rather because
Living things don't look like they were designed. They don't look remotely designed, at any level, from super-macro to super-micro. From forests to molecules, the incredibly paucity of structures or systems that even vaguely resemble human creations is astonishing. Sure, we've copied natural features to supplement our terrible, inefficient, and ridiculous attempts at designing usefull things. But nothing that we do looks even a little like the inside of a cell, ccd chips don't look like retina, we can't build a decent sphincter and as for proteins... don't even get me started. We can't even model the mechanisms of protein folding, much less design something that works like one. Nothing designed looks or behaves anything like a protein.
I'm not sure, though. I'm not convinced that saying something is more complicated than anything we can design necessarily implies that it therefore doesn't look designed. And I think maybe Seth is misinterpreting Dawkins. I doubt very much that any biologist (well, except Behe), would say that living things look designed once they're examined properly. But I think it is the case that on first, uncritical glance, living structures can look designed. Once we understand how evolution works, of course, then that becomes a better explanation for what we see, because it accounts for inefficiencies and suboptimal configurations that intelligent design wouldn't bring about. So on more detailed examination living things don't look designed, because they instead look evolved.
Of course, this is all very fuzzy, because we talk about things that may or may not "look designed", but we never really say what 'looks designed' means. I think we need a specific definition for that term, but I'm not going to provide it because I'm tired.
And there are other, entirely sufficient reasons why ID is a non-starter. It makes no predictions. It has no explanatory power. It is therefore not falsifiable.
What more do we need?
So, yeah, I take it back. I think Seth is wrong.