At Cafe Hayek, Don Boudreaux writes a response to the scarcityist argument, as he puts it:
[P]rotectionism is justified if enough consumers or voters are willing to pay higher prices in order to help workers.
Don lists three reasons why the scarcityists’ reasoning is incorrect. Below is my addition of a fourth reason from the comments section of that post:
I’d add a fourth one, one which shows that this scarcityist’s plan to save jobs though higher prices cannot work:
When the relative prices of protected domestic goods rises, then some sacrifices must be made. Scarcityists assume, incorrectly, that all the goods where quantity demanded falls is from the importers rather than the domestic producers, and thus only foreigners’ jobs are harmed. But this is not so; we only import a fraction of our goods. If the relative prices of domestic protected goods X, Y, and Z rise, and if the scarcityists do not change their purchases of X, Y, and Z, then necessarily other purchases of domestic goods that were not subject to import competition (say, goods A, B, and C) will be cut back. For instance: if one has to spend more on sugar, steel, and toys, one has less to spend on dinner out, movies, and baseball games.
The scarcityist may respond by saying “But wait! I am not on my budget constraint. I don’t spend every penny I have. I can afford to spend more.” I have two responses to this: 1) Good for you, but for many of us, we are not that wealthy, and 2) Then that necessarily means you are saving less. By saving less, there are less loanable funds, which means less money for people to borrow to build homes and businesses, persue education, buy cars, etc. So, you’re taking jobs away from people in construction, business, education, automaking, etc. In short, as long as relative prices rise, quantity demanded of something has to fall. Why? Scarcity is still a thing.
In his 1971 book “Economic Theory,” Gary Becker has a neat little proof of this (see pages 21-23 of the 2007 edition). A more detailed proof and discussion can be found here: http://www.jstor.org/stable/1827018