David Ricardo mathematically proved it was a bad thing over 200 years ago. It absolutely befuddles me that people, especially in scientific communities, continue to support its implementation. Hong Kong has always been free trade and their GNP per capita is now greater than all of western europe, barring Norway (which is equal to HK). Protectionism makes yourself poorer.
Isn't interesting concerning tariffs that what we do to our enemies during wartime we do to ourselves during peacetime.