In January 2003, Professor David Bradford told a New York Times reporter that a consumption tax discourages work effort. Shortly thereafter, he received the following e-mail: “Since when is a tax on consumption a disincentive to work?

This sort of specious reasoning ran amok in this article. I laughed as I saw it was labeled

‘Economic Analysis.’ ” Who was correct, Professor Bradford or his correspondent? Justify your answer using either an arithmetic or algebraic argument. [Hint: Bradford was right.]