How high is the price we would pay for justice?

A sense of justice and injustice is an evolved moral emotion to signal to others that if exchanges are not fair there will be a price to pay. In the Ultimatum Game, in which one person is given a sum of money to divide with another person — with the stipulation that if the offer is accepted both keep the money, but if the offer is rejected no one gets any money — offers less than 30 percent of the sum are typically rejected. That is, we are willing to pay 30 percent to punish an offender. This is called moralistic punishment.

It might surprise you to learn how much of everything we do in a typical day we do out of habit without even thinking about it. We don’t even remember how those habits got formed. I’ll bet that you tend to wash yourself the same way each time you take a shower. If so much of what we do in a day is made up of habits we formed without realizing it, why does it seem so hard to change habits or create new ones?