Forty-odd (exceedingly odd, I might add) years ago, who would have envisioned a national war against drugs? Nobody took drugs -- nobody you knew, nobody but jazz musicians and funny foreign folk. Then, after a while, it came to seem that everybody did. Drugs became a new front in the war on an old social culture that was taking hard licks aplenty in those days. I still don't understand why people take drugs. Can't they just pour themselves a nice shot of bourbon? On the other hand, as Gary S. Becker and Kevin M. Murphy argue, in a lucid piece...