Education: The Stretch

In a classroom at the University of Chicago one morning last week, a group of city high-school students wrestled with an odd sort of problem. The class happened to be in mathematics, but the sort of math the teen-agers were tackling went far beyond anything that even most college students know. Based partly on the theories of Alfred North Whitehead and Bertrand Russell, it involved symbolic logic and sentence calculus. "Logically valid conditionals and bi-conditionals, or the implications they embody," blithely explained the professor, "give rise not only to rules of sound inference—by...