Living systems reproduce.
Paley's watch doesn't. In the case of the mousetrap or Paley's watch, we are forced to conclude human design and manufacture because there is no pathway to the fully developed state. It may only be because of my scientific naivete, but I had some trouble with Glenn's statements. Since we were dealing with Mike Behe's mousetraps, it would be helpful to take a look at DBB, where he officially sets out his case. I'm still trying to get all of the arguments straight, but this seems to me to be a very compelling argument.