I used to think so, before I understood that we live in a mercantilist world economy. I still think protectionism would be bad in a less distorted economy, and I think it's bad in as-distorted an economy as ours (because people who are subjected to pressure are more likely to be adaptive and dynamic), but it's harder to make the case, don't you think?
Protectionism means you're protecting inefficient industries. In a global marketplace, this means industries in other countries will out-compete yours.
What I meant is that in mercantilist world you do have asymmetrical protectionism, and that has real-world effects that require more thought than simply standing by the free market position, because it's not a free market even if you try on your end.
Usually they out-compete yours because they burn coal and you have to buy solar, they commute in packed trains while you drive tesla to work, they live in tiny apartments, while your house has a backyard and frontyard.
Protectionism is not a fix for comparative advantage. Regardless of the motives for protectionism, it will make your economy less competitive and less prosperous.
