When is a Radar Trap a Contradiction?

A visitor from China was riding along in the heartland of America when he noticed and asked his driver and host about the gadgets on the dash of the car.

The top one was the radar detector to warn the driver of speed traps ahead, the American executive explained. The second one was a laser detector because some of the speed traps, in order to outwit the radar detectors, were using lasers instead. "This is high technology in action, you see," the American said partly in jest.

The Chinese thought for a while and then said, "Did you know that the Chinese term for contradiction is literally made up of two characters: "maodun" which stands for spear and shield?

"During the warring states period in ancient China, so the story goes, there were two shops next to each other in the capital. The sign on one store proclaimed that it made the world's sharpest spears guaranteed to penetrate any shield. The other store proclaimed that it made the world's strongest shields guaranteed to block any spear."