Not only is he well known, to many he is also known for his outstanding work on Scientific American Frontiers.
He hosts Scientific American Frontiers and is a visiting professor at Stony Brook University’s Center for Communicating Science. His status as a movie star will draw attention to the debate.
With his well-known left-wing political views, he would not be considered fair by the Republican party and they would not accept him as moderator.
To be fair, the moderator can't be a left-wing activist or a right-wing activist.
Judy Zlatnik commented
He is also well versed in scientific issues and would brook no B******T!
Christine Aidala commented
Disseminating science more broadly is something about which he cares deeply. He was instrumental in establishing the Center for Communicating Science several years ago at Stony Brook University (http://www.centerforcommunicatingscience.org/).
Carol S. commented
This is the first person who came to mind for me (especially because of his role with Scientific American Frontiers). Although he probably favors a liberal perspective, I don't think he is seen as polarizing with the public. His sense of humor would be a big plus.