Tariffs are a political instrument for revenue to fund the government, to protect critical industries (as politically determined) or to punish an offending nation with high trade barriers.
In 1940 the US and world economies were in a state of collapse one of the reasons for that collapse was the passing of the Smoot-Harley Law in 1930 which killed international trade. Our growth prior to that was military based from WW1 and the void left by the destruction of the British Empire in that war.
It is no news that China does not have free trade but restricts the freedom of its citizens and seizes the profits from international trade. Surely that is not what you want.
Tariffs can easily by turned into an instrument of oppression as in a totalitarian society like China.
http://www.encyclopedia.com/history/encyclopedias-almanacs-transcripts-and-maps/tariff-act-1789
Again, a duty of Congress to regulate trade with other nations.
Smoot-Hawley is a red herring. There is no serious scholarship which attributes the collapse of trade in the 1930s to Smoot-Hawley.
Germany saw an 80% reduction in both imports and exports and was nearly completely unaffected by the law. The same applies to most of Europe.
The US suffered a 50% loss, coincident with far greater losses of net trade worldwide.
Serious scholarship says Smoot-Hawley contributed to the deflation of the 30’s, but to contend that Smoot-Hawley precipitated that is not supported by any research that I am aware of.
The world economies were already collapsing in upon themselves when it was enacted.
We got a Smoot Hawley lie propagator. LOL.
For anyone that isn't brainwashed Smoot Hawley had little or no impact on the Great Depression. Why? Trade was only 4% of the total GDP in 1930 so it couldn't have great impact.
The great Depression was a financial crises and a banking crises Smoot Hawley had nothing to do with it. It as passed the year AFTER the crash.