Matthew Yglesias makes the case for labels.
Normally, how much you’re willing to pay for a good or service depends on the quality of the good or service in question. But there’s no way to sample the quality of a can of soda without buying it first. So how am I to know whether or not I want to buy that can of Diet Coke? Well it’s simple. I may not have had that can of Diet Coke before, but I have had many other cans of Diet Coke. And I can infer that the Coca-Cola corporation, having invested a great deal of time and money in building the Diet Coke band is going to make a good-faith effort to turn out a consistent product … The rise of recognizable and coherent parties creates some challenges for American political institutions, but the correct response is to tweak the institutions not to spend time wishing for label-free politics.