Some will say that this analogy is true for art and engineering, but not for biological systems. Even though a fine painting or the Golden Gate Bridge obviously didn't just happen by chance, biological systems have ongoing processes that don't occur with paints or bridge components. I agree that this contention has some truth. However, as noted above, even in biological systems, undirected evolution of functional complexity still has theoretical problems (ie the math situation mentioned above). Therefore, I still contend that complexity, whether in biological or nonbiological systems, can give evidence for design.
One more comment. Some scientists simply say that an intelligent design hypothesis has no place in science. However, this assumption is generally made without scientific support as to why it is true. In fact, the search for intelligent design is used all the time in certain aspects of science. For instance, forensic science tries to discern if a possible crime was an accident or "designed." Similarly, archeological science looks for evidence of design and seeks the identity of the designers.
Some people counter this argument by saying that for archeology or crime cases, we know there could be an intelligent person behind the observation (ie we know that people commit crimes or make artifacts). On the other hand, in the case of living systems, we haven't ever seen one originated by a personal designer.
One flaw with this response is that the same criticism can apply to saying evolution produced very diverse creatures. We have never seen a new creature arise simply by random, natural processes. In making this statement, I am excluding small developments created by artificial breeding. This would include fruit fly "species" that cannot mate with each other, as well as some plant breeding phenomena. These developments involve very small effects compared to what must happen to start with slime molds and evolve biochemists and race car drivers.
There is another flaw with the "we never saw this" statement. Just because one has never seen a divine designer, doesn't automatically mean one does not exist. Unless there is reason to rule out the possibility of a designer for living species, then one is possible. “
Robert DiSilvestro, Ph.D. Biochemistry