How did we end up in a world where Big Gulps are being banned in New York while the welcome mat for potheads is being rolled out in Colorado? How is it that cigarette smokers are pariahs, while people smoking weed are being cheered? This is despite the fact that potheads are almost universally recognized as unmotivated, low class, degenerate – and, yes, smelly failures. Even the ones that get somewhere in life, like Barack Obama, usually turn out to be mediocrities. Moreover, we all recognize that smoking is a dirty habit that makes you die younger and while drinking...