Except, the USA government does not obtain consent before governing a person.
As far as how it started, here's a great introduction to the Great Debate. It's a description, in the Framer's words, of the issues they saw at the time the Constitution was created. Note that during the Constitutional Debate Jefferson was mostly neutral. Once he started serving in Washington's cabinet, however, it became obvious that these two strains of thought were always going to oppose each other. Jefferson noted that each day he girded himself to prepare for battle. Washington as well tried to stay above it all, and managed to do so during his presidency. Afterwards it became obvious that he was more of a smart-guy-and-structure person, but he managed to keep that mostly under wraps.
American Democracy is about the consent of the governed. It always has been. If you read both the Federalist Papers and the people who were arguing the other side, it's quite clear that the anti-Federalists had some really good points. Many of the predictions they made about the future course of the country were proven correct. Their arguments caused so much concern that a Bill of Rights was a precondition to adoption of the Constitution.
There has always been two strains of thought in America. Strain 1 says that people should be led by their betters. Heck, even Jefferson privately acknowledged that there is a natural aristocracy among men. These people feel that with the right people in charge, working the right system, the sky is the limit. If things are wrong, it's a problem of not having the right person. Government consists of doing whatever it takes to make the quality of people's lives better.
Strain 2 feels that all systems of government are broken, mainly because it's impossible to have a government that doesn't involve men, and men are fallible. I agree that this has some religious roots, but it also has roots in a study of history. As Thomas Paine pointed out -- not the religious person by any means! -- a man who has a king for a tyrant knows who oppresses him. But a man who is a serf to a complex system of bureaucrats is just as oppressed, only he has nobody to point a finger at. Strain 2 believes that every time structure is added, the system becomes more and more broken. That even if you had a super smart person, they'd more as likely be a dictator than a savior. Government consists of doing as little as possible to prevent people from harming each other.
This fight continues today. The constitution was a compromise between these two strains of thought. That's why it's worked for so long. Good government consists of a balance between these two schools of thought, with some kind of reset option every now and then when the system gets too much cruft in it(in my opinion)
So Joe Sixpack who knows nothing votes, but he votes instead of marching in the street with guns. Clyde Wineglass (Joe's cousin who went to Harvard) votes, and by voting he also blows off steam. The major parties exist solely for giving the illusion that things are changing every few years, which makes Joe and Clyde feel better about voting. Over time, each of them builds up a long narrative about how their party almost did this or that, but the other party stopped them. By having a "good" party and a "bad" party in their mind, each of them is able to deal with their frustrations about government without actually becoming angry with the government. This allows our civilization to continue.
It's interesting to observe how different the idea of parties (or "factions" as I think Madison called them) turned out to be compared to what the founders thought would happen. Sometimes you get it right even when you screw up :)
Sorry if that was a little cynical, but that's the way I currently understand it. And I agree with grellas, these guys are off-base. This entire line of science-of-irrationality, as it applies to politics, is a threat to this system of consent, because it threatens to put people in boxes. In addition, it continues to politicization of science. Either of these would be bad by themselves. Combining the two? Ugh.