“This is a profound enough point worth dwelling on for a moment. When a division exists inside a party, it gets addressed through suppression or compromise. Parties don’t want to fight among themselves. But when a division exists between the parties, it gets addressed through conflict. Without the restraint of party unity, political disagreements escalate. An example here is health care: Democrats and Republicans spend billions of dollars in election ads emphasizing their disagreements on health care, because the debate motivates their supporters and, they hope, turns the public against their opponents. The upside of this is that important issues get aired and sometimes even resolved. The downside is that the divisions around them become deeper and angrier.”