Are environmentalists more inclined to take moral shortcuts? That's what Julian Baggini suggests, picking up on research showing "that the greener people are, the more likely they are to lie and cheat." It's consistent with an earlier study showing people who recycled were more likely to feel entitled to taking long, carbon-emitting airplane flights.

This is great fodder for people sick of green sanctimony, but Baggini thinks "it would be wrong ... to think there is something particularly hypocritical about environmentalists." Instead, "the general truth lurking behind these findings is that the feeling of being pure is a moral contaminant." How so? Baggini thinks that feeling virtuous may have two harmful effects: (1) complacency, and (2) a tendency to use good deeds like currency. In other words, we assume we deserve something good when we do something good. (Baggini thinks evolutionary biologists might talk about "reciprocal altruism" here.) And, finding no one to reward us, we reward ourselves.

That may indeed be natural, but that doesn't make it right. And even if it did, there is still a problem that when we allow ourselves to dish out the rewards, we can't trust ourselves to be fair. It's like that old Laurel and Hardy skit where Ollie shares out the money, "one for you, one for me; two for you, one-two for me ..." and so on. He who cuts the cake should never be allowed to choose the first slice.

The problem is compounded by the fact that we also tend to over-value the good we do and undervalue the harm. The more you believe that saving the world is the most important thing in it, the more your credit for doing your bit is inflated. Our own moral priorities always, uniquely, earn double points.

So what's the solution? Baggini proposes the following moral conundrum:

Consider, for instance, how you'd answer the question, are you modest? The truly modest can't answer yes, as that would be immodest. But to answer no would be false. The only honest answer that is not self-defeating is to say, "I don't know: I try to be, but I might not succeed."

Is it possible to apply this without getting tangled in knots? Is there a way to be good without suffering the ill effects of sanctimony?