Indeed, while people are entitled to believe in horoscopes, trust in crystals to bring good luck, or buy into quack medicine, such “junk science” becomes a serious threat to society when it is allowed to influence public policy. Consider, for example, the response last year by some activists in Key West, Florida, to efforts aimed at stemming the spread of dengue fever, a serious, potentially life-threatening disease, which reappeared in the area in 2009 after being absent for more than 70 years.