And that's pretty ambiguous. Surely we can't just talk about direct material return, dollar for dollar - we'd have to talk in terms of what bundles of goods people are willing to buy, and under what circumstances. But we can only have that conversation in a context unpolluted by the utter nonsense of the "I've got mine, Jack" right.
This, again, is where we have to reconstruct the consensus that the Friedman school has done so much do destroy. Because clearly, beggar-thy-neighbor is not the way any human being actually wants to live, so the arguments against taxation fall apart at their conclusion. A set of premises which leads to an absurd conclusion is absurd, ergo, the Chicago Gang is absurd.
So once more, we're back to "which taxes are reasonable?" And here, economists could do a lot of good, if they'd plant one foot on each buttock and pull until their heads came popping free. Because economists have a set of tools with which to analyze the actual results of policies. They can supplement the naive intuition which can lead to poor policy, and offer some depth to the discussion.
What they shouldn't try to do is value judgements, since value judgements are in fact the question we're trying to answer. If they begin by assuming that gilded-age laissez-faire sink-or-swim is morally correct, the economists have sidelined themselves from the discussion before they say one word. Their input is useless, since it's aimed at supporting a conclusion known a priori. On the other hand, if they come to the table in a spirit of honest inquiry, then they're incredibly useful. Who knows, if that were to happen, an economist might someday get laid.