Why?

Intellectual consistency is always thin on the ground, so I don't agree with Professor Mankiw's assertion: "If you are going to take that philosophy seriously, you have to take all of the implications seriously." I'm certain most Americans, perhaps even all of them, agree that Bernie Madoff's Ponzi scheme was immoral, but support for ending the Great American Ponzi Scheme of Social Security is non-existent.

Professor Mankiw continues with this simile:

It is more like your mother telling you to clean everything on your plate. If you are a Utilitarian redistributionist, the height tax is like that awful tasting vegetable your mother served up because it is good for you. No matter how hard you might wish it wasn't there sitting on your plate, it just won't go away.

Sure it will! My four year old finds all kinds of ways to make it go away. She begins by whining about it to see if her parents will capitulate. Failing that, she might chew it up a bit and gag, requiring her to spit out the offending vegetable, or she'll play a variant of "there's many a slip 'twixt the cup and the lip." Oops! It's on the floor so she can't eat it now. To put it another way, Utilitarian redistributionists can ignore the height tax because their "parents", the people that elected them, will not demand intellectual consistency. The redistributionist is excused from the table while the unwanted vegetable languishes on their abandoned plate to be discarded with scorn by those who fail to hold them to account.