In The Big Questions Steven Landsburg examines the problem of belief. He points out that 96% of Americans believe in God, but most go through their lives acting as if they don't believe in God. That raises the question of what do we mean by "belief"?
At one point Landsburg makes this interesting observation:
Sometimes we lie; sometimes we mouth platitudes. Many an atheist has thanked God for a Red Sox victory or promised to keep a sick friend in his (nonexistent) prayers. And sometimes we express our instincts instead of our thoughts. We scold and threaten our computers, even though we don't believe for a moment that they actually hear us.
Now, the cognitive scientists will tell you it's not that simple - depending on what you mean by belief, it's perfectly possible for different parts of your brain to believe contradictory things. One part says, "I think I'll have another cashew," while another says, "No. Don't you dare!" Perhaps some part of your brain does believe your computer is listening even while the thoughtful parts know better. But here's the sense in which I mean you don't believe for an instant in your computer's sentience: If you had to bet all your wealth (or your child's life) on the matter, there's no question which side of the bet you'd take.
It seems like people often hold contradictory economic ideas in their brains at the same time. Perhaps in their reptilian brains people are crude Keynesians or crude Austrians. At cocktail parties the crude Keynesians will claim that monetary stimulus will no impact at the zero bound. The crude Austrians will complain that QE will lead to hyperinflation. But when they go down to Wall Street, they put aside their reptilian brains and start buying and selling stocks, T-bonds, and TIPS as if QE has some impact, but will not lead to hyperinflation.
Of course this is also true of politics. What do Americans really believe about NSA spying? If the answer they gave were their "true belief," then would it matter whether Bush or Obama was president at the time?
Bryan Caplan seems to understand this point, as he likes to bet with people who say they hold different beliefs. As soon as money is involved, it becomes easier to infer people's "true beliefs," or at least the beliefs of what Landsburg calls the "thoughtful parts" of the brain.
I tend to avoid betting on beliefs, as I think one can get even better information from looking at market forecasts, where millions bet on their beliefs. Market monetarism is a sort of bet on the proposition that betting elicits thoughtful beliefs, and that the thoughtful beliefs of the crowd are humanity's best guess as to the "Truth."
PS. About the term "reptilian brain:"
1. It's a giveaway that I'm 50 years behind in cognitive science.
2. I don't mean it as a pejorative. Dinosaurs lasted 200 million years; we'll be lucky to last another 200. On the other hand I'm told dinosaurs were not exactly reptiles.
3. I also hold many incompatible beliefs in my brain, at the same time.
PPS. The post title is of course half-joking. What can lying mean when we have multiple beliefs? And it's a reference to the best song on the best rock album.