For those of you who aren't watching the Roberts confrimation hearings (why would you? he's getting confirmed no matter what), here's the breakdown of whats going on.
Republicans know he's going to rule in their favor for the most part, so they are trying to say that the only questions people should ask are about his ability to judge cases fairly based on the facts presented. Republicans are basically trying to not have him answer any questions that might show his political inclinations about anything.
Democrats know he's not going to rule in their favor for the most part, so they are trying to say that he has to talk about his political ideology because its impossible to be completely unbiased as a judge (for an extreme example, see Scalia). They want him to say something so dumb that it makes it impossible for him to get confirmed.
It is a shame that a guy who will probably be the Chief Justice for the next 30 years is probably going to sit there and not answer any questions about his fitness to serve and get confirmed anyway because of the Republican domination of the government. The founding fathers are dusting off their Sit 'n Spins right now.