The discussion in the combox for American Protectionists, Unite has been interesting.
Often one will put the debate over "free markets" in terms of freedom--I should be able to purchase a product from whomever I wish, especially if I have the good reason that it is cheaper. While this makes sense within a political community, it is not so if one makes this freedom (or right) or other economic 'freedoms' absolute, so that I can make any transaction with anyone anywhere. Why? Because one has a duty first to help one’s neighbor before helping someone distant--one forgets that commercial transactions are a form of help whose purpose is to help others and the community as well, not something aimed only at my own benefit. Do the libertarians have different first principles that would contradict the former and support the latter? Economic transactions by their nature are a form of mutual support--they should not be acts in which each party acts out of self-interest and hopes to maximize their own benefit, without any any concern for the other party.
I haven't made up my mind regarding tariffs as a form of protectionism, but what other means are there to curb economic behavior that may "benefit" the individual but hurt others of the community, and the community as a whole? How does one reinforce the primary obligation that members of a community have to each other?