Everyone knows that tall people make more money (and get more girls) than short people, so Greg Mankiw is right to wonder how much we should tax height.
Should the income tax system include a tax credit for short taxpayers and a tax surcharge for tall ones? This paper shows that the standard utilitarian framework for tax policy analysis answers this question in the affirmative. This result has two possible interpretations. One interpretation is that individual attributes correlated with wages, such as height, should be considered more widely for determining tax liabilities. Alternatively, if policies such as a tax on height are rejected, then the standard utilitarian framework must in some way fail to capture our intuitive notions of distributive justice.
In other words, if you're against taxing tall people based on height, then your view of "distributive justice" is flawed and you should reconsider your support for tax policies that take from the rich and give to the poor.
(Also, tall people may earn more simply because they're smarter.)