Gerald Dworkin in the New York Times:
Most of us believe that lying is wrong. We teach our children that it is wrong, and hope or expect that value judgment is shared by our friends and family. In public, we decry politicians and public officials when they lie, which we have frequent occasion to do these days. But the truth about lying is more complicated.
We tell lies to one another every day. But when we commit other acts that are generally believed to be immoral, like cruelty and theft, we do not seek to justify them. We either deny that the acts we committed are appropriately described by these terms, or we feel guilt or remorse. But many of us are prepared to defend our lies: indeed, to advocate their general use. Of course the Nazi at the door inquiring about Jews within ought to be lied to.
But perhaps this example only shows that there is not an absolute prohibition on lying. Such cases are rare, the harm to the innocent clear, the wickedness of the aggressor obvious. I want to argue that the number and types of permissible lies are much wider than one might have thought.
I am not arguing for the view that lying is morally neutral. I accept the fact that there ought to be a strong presumption in favor of honesty. But it is a presumption that not only can be, but ought to be, overridden in many more cases than we assume.
More here.