In case youve been living in a cave, theres been this hubbub about cell phone use in cars. Drivers yapping away, they say, are causing untold accidents. There oughta be a law, and in some places there is.

The whole cell-phone uproar makes sense, at least the common kind: It seems obvious that if youre talking, you aint watching the road. But just because something is obvious doesnt mean its true. I mentioned once before that in the 1970s it was obvious that global cooling was a major problem for the planet; the majority of scientists said so. (Theyve changed their minds.) In the early 80s, common sense said that VCR would kill the movie industry. (It hasnt.) Many people still think that you can catch a cold by being cold. (You cant.)

So it may seem obvious that talking on cell phones while driving is dangerous. But wait a second. Did you know that there were similar concerns about car radios? People were sureand it made common sense back thenthat listening to the radio distracted you from driving. (They were right. Hang on a moment.) Before that, the fuss was over windshield wipers: The back-and-forth motion would keep drivers from focusing on the road. Hmm.