Fris: You don't always have to change someone's belief or their mental model to get them to do a behavior. The powers that be put chloride in the water supply back ofth ten fifties as a simple way to fight tooth decay. Portland, oregon refuses to floridate its water. Go to portland, ask people there how many cavities they have. They would rather sit in a dentist's chair all numbed up and get drilled for an hour, then have the government slip something harmless in their drinking water.