Most of us, including myself, like to think that we are pretty rational thinkers, and that we make our decisions on the basis of facts and common sense. So whether it's choosing the brand of peanut butter we buy or who to vote for for President, we claim to have reasons and to have thought the whole thing through.
But actual experimental evidence shows that we are actually pretty irrational in what we do much of the time. Game theory and economics are based on the idea that we are rational actors who can determine what's to our own benefit and who will act on that information. However, people don't act like that in real life. For a quick example, $1 saved is $1 saved, regardless of how we come by it. So if $2 toothpaste is $1 off or if a $20,000 car is $1 off, it's the same benefit. But I would bet that there's no one who would care about saving $1 on a car, while almost everyone would be glad to save 50% of the cost of a tube of toothpaste. And if a $1 item is offered for free, we'd all get excited. And yet in terms of our finances, it's still just $1.
Advertising is built on the fact that we tend to like and trust things that we are familiar with. Advertising long ago gave up on giving us factual data, and instead it works almost entirely at causing us to feel some sort of emotional attachment to a brand. We all like to think that we're not swayed by advertising, but the evidence is against us. We might react negatively rather than positively, but on the whole, advertisers pay big bucks because their stuff works.
Psychologically, we all tend to divide the world into "us" and "not us." This is an essential survival strategy left over from our tribal past, when our survival depended on generalizing quickly and acting instinctively thereafter. For example, if I meet one grizzly bear and it attacks me, the next time I see a bear, I don't have to stop and wonder if this bear is as bad as the last one. I just run. And if I meet a member of another tribe who might kidnap me, I run as well. So we quickly size up whether a person is "one of us" or a dangerous alien.
In politics as well, while we offer reasons for who we choose to vote for, our reasons are likely to be rationalizations rather than real logical reasons. We want someone we can identify with, someone who is "one of us." We respond at a level below the rational to advertising of all sorts, and most of politics is conducted through advertising. Sensible candidates know this, and they go to a lot of trouble to "identify" with us in various ways. We may be reacting to candidates as images of parents or potential spouses or bosses or friends. When Christian conservatives vote for Bush or Huckabee, they are not doing so because they necessarily agree with a flat tax or an opposition to nation-building. It's because they feel, "That's me. That guy represents me." When people hate Hillary Clinton, it's not really because of the details of her health plan. It's because she reminds them of a teacher who humiliated them in 4th grade or the smart girl in class who wrecked the curve in Soc 101.
Our rational brain is the weakest link in our mind. Anything that we have to think about, we do poorly. As long as we're thinking about how to drive a car, we can't really drive. If we have to think about grammar rules, we can't speak fluently. Geniuses in math and science "see" patterns in a flash of insight, and then have to laboriously try to reason their way to a proof after the fact. We are very good at seeing patterns. We are very poor at reasoning analytically. We actually feel the strain of trying to think something through, whereas things that are below the level of consciousness, like speaking our native language or walking or driving a car, are effortless.
One of the arguments against Obama is that people's attraction to him is not based on good solid policy reasons. But no one ever became a Democrat or a Republican or a Libertarian or a Green by a careful cost/benefit analysis. We identify with a certain position at subliminal levels. Those who choose McCain may be responding to his courage in North Vietnam, which tells us almost nothing about how well he'd do as president. Those who choose Hillary may see her as embodying their hopes for a gender-equal society. So what does Obama represent that is so attractive to so many? He's part Tiger Woods and part Robert Kennedy and part Morgan Freeman and he's young and vital and new. He's black and white, he's rich and poor. He's American and foreign. And a lot of people find that more attractive, at a gut level, than a Vietnam vet or a Mormon or a pastor or a nagging mom or a 911 mayor or an actor or a southern populist. They say, Yup, that's us.
And then we hope to God that the person we've projected our hopes into can do the job.