In his new book, Thinking Fast and Slow, Daniel Kahneman illustrates a lesson of central importance to bleeding heart libertarians: that if you want to help the poor, trusting your intuitions about how to do so is a bad way to go.

Kahneman illustrates this point with a story from Thomas Schelling’s Choice and Consequence. Schelling was teaching at Harvard’s Kennedy school on the topic of child exemptions in the tax code.

Schelling told his students that a standard exemption is allowed for each child, and that the amount of the exemption is independent of the taxpayer’s income. He asked their opinion of the following proposition: should the child exemption be larger for the rich than for the poor?

Of course, almost all of the students said that it should not. And I’m sure your intuitions were the same.

But then Schelling did something interesting. He pointed out that the tax code could have been set up differently – that instead of assuming zero children as the default and then giving tax credits for those families who have more, it could have assumed, say, two children as the default and then impose surcharges on those who have fewer.

He then asked the following question:

Should the childless poor pay as large a surcharge as the childless rich?

Your intuitive reaction to this question, like that of the students, was probably immediate: “No.” But there’s a problem. Our intuitions say that the rich should not receive a higher credit than the poor, but that they should pay a higher surcharge. But as Schelling pointed out, “surcharge” and “credit” are just two different ways of describing the same thing, a purely verbal distinction created by an arbitrary choice about how many children we assume as the baseline case. So what our intuitions are telling us to do – have the rich pay a higher surcharge but receive a lower credit – is logically impossible.

Kahneman’s diagnosis:

[Relying on our intuitions] delivers an immediate response to any question about rich and poor: when in doubt, favor the poor. The surprising aspect of Schelling’s problem is that this apparently simple moral rule does not work reliably. It generates contradictory answers to the same problem, depending on how that problem is framed.

And it’s not just that framing effects distort our reliable judgments about reality. It’s worse.

Framing should not be viewed as an intervention that masks or distorts an underlying preference. At least in this instance – and also in the problems of the Asian disease and of surgery versus radiation for lung cancer – there is no underlying preference that is masked or distorted by the frame. Our preferences are about framed problems, and our moral intuitions are about descriptions, not about substance.