We already have set a precedent with cigarettes. And the argument most often employed by sin tax proponents revolves around economic externalities -- or the idea that everyone shouldn't have to pay for the destructive habits of the few. (Though there is evidence that the societal cost of the obese is largely inflated, as it were.) I have a lot of sympathy for this argument. So perhaps all citizens can begin taking fiscal and moral responsibility for their own behavior. …
… I'm just kidding. That's crazy talk.
But once we start rationing health care, externalities will only become more of an issue. If we collectively pay for health insurance, then what is to stop the majority of us from dictating to the minority what it can eat or drink?
What would stop Republicans -- after they roar back to power in 2048 -- from levying sin taxes on promiscuous behavior? After all, promiscuity burdens all taxpayers through sexually transmitted diseases, unwanted pregnancies and Lindsay Lohan.
If government continues to manage social behavior through taxation, why not give it a shot? It's the moral thing to do.