The first point one has to get straight in discussions like this, is that ID is not the opposite of evolution. Rather, it is the opposite of Darwinism, which says life evolved by an utterly unguided, undirected mechanism. If god directed the process of evolution, or rigged the universe to produce complex life, then that is not Darwinism - it is intelligent design.

There is no publication in the scientific literature - in prestigious journals, specialty journals, or books - that describes how molecular evolution of any real, complex biochemical system either did occur or even might have occurred.

In private many scientists admit that science has no explanation for the beginning of life... Darwin never imagined the exquisitely profound complexity that exists even at the most basic levels of life.

As can be seen even by this limited number of examples proteins carry out amazingly diverse functions.

In Darwin's time all of biology was a black box: not only the cell, or the eye, or digestion, or immunity, but every biological structure and function because, ultimately, no one could explain how biological processes occurred.

I believe the evidence strongly supports common descent. But the root question remains unanswered: What has caused complex systems to form?

In order to say that some function is understood, every relevant step in the process must be elucidated.