If it saves just one life

Hovering in the background of church closures is the view that I have no right to put you at risk. Related to this is the ethical assumption that restrictions are justified "if they save just one life".

But as a matter of public policy and private behavior, no one actually operates with the principle that a restriction is justified or morally mandatory if it saves just one life. To begin with, that's hopelessly unrealistic. Life contains inevitable tradeoffs. Overprotective policies that save some lives do so at the expense of taking other lives. Policies have unintended consequences. There are no cost-free solutions. 

So what we're really dealing with is the sorites paradox or little-by-little arguments. There is no intrinsic cutoff. So it's a question of degree. How much risk is acceptable? How much is too much? How much is too little? There is no ideal answer. But we need to avoid certain extremes that lead to moral and practical paralysis of action.