Ezra Klein offers an analogy about mandates:
First, Obama aside, mandates matter because, sometimes, folks have to be protected from their worst instincts. That's why we force everyone to pay into fire departments through taxes. Otherwise, some folks would opt out under the theory that they don't do much cooking, and we don't want their houses to burn down.
But this is not true. We force everyone to pay into fire departments because fires have very bad negative externalities: if your house catches on fire, unless you live on a rural farm, there's a good chance that your neighbor's house will burn down too. Fire prevention is a genuine public good; most health care, with the exception of things meant to stop the spread of infectious disease, simply isn't.
One can make a modestly compelling moral hazard argument for a mandate--people will be tempted to free ride on the rest of us, knowing that we won't deny them health care in extremis, so the only thing to do is make them pay up front. But I'm persistently disturbed by the notion that most of our fellow citizens are intellectual children who need to be forced to do what is good for them even at massive cost to their liberty, and ours.