As with rational actors and efficient markets, the strong form of the wisdom of crowds theory is too silly to bother with -- a collection of motivated reasoning and epicyles -- but the weak form stands up fairly well and, at the very least, serves as a very useful rule of thumb. Under the right conditions, more heads really are better than one.
When, however, we try to determine how much better, we run into a paradox, or at least a tricky caveat. We are often most likely to rely on collective opinions when we should trust them the least. This is especially true in cases of limited information.
When reasonable people want to understand something or make a decision, they generally seek out both objective information and informed opinions. Furthermore, being reasonable, they constantly try to gauge the quality of that input and give more weight to the good and reliable. Unfortunately, our ability to judge the information other people are using is less than our ability to judge the information we’re using. This leads to a big problem when everyone is using the same basic set of facts.
If I feel ignorant on a subject, I’m more inclined to rely on your take. If you feel ignorant on a subject, you’re more inclined to rely on mine. Extend this out to a large number of people and limit their ability to share their uncertainty and you can see where this is going.
Which brings us to primary polls, noise and path dependency.
Supporting a candidate partially because other party members support her is not necessarily a bad thing. In a democracy, agreement is a positive and if you believe elections have consequences, it is only ration to consider electability (with the caveat that much of the conventional wisdom about electability is demonstrable bullshit). Six months from now, ignoring the polls when deciding who to support will border on irresponsible.
At the moment, though, the focus on polls and horse race coverage actually damage the democratic process, amplifying noise and creating the illusion of information. With all due respect to Nate Silver and his peers, if they would all just take the next few months off, the country would be better off.