Well trade is free in name only when you consider the fact that the various treaties where its proponents claim it opens markets there are provisions/regulations that either protect specific industries or make it easier to litigate for one party but not others. Every nation tries to press their thumb on the scale in their favor. China does it with its steel industry. The US does it with IP. European nations do for their own industries and so forth. No one plays by the same rules nor are held accountable for their subterfuge. Everyone just flashes their fake smile, shake hands, and look good while everyone on Main Street lives on less so Wall Street can get its shareholder value.

Mind you, I don't believe that economics is a zero sum game. It's just that economists refuse to acknowledge their ideological biases which muddies the discussion. Ideologies are fine if you're willing to state your position and defend it with facts. But that's not how economists seem to be working (orthodox and heterodox schools all do it) an angle to insert their favored ideology into the political machine through fraudulent means (by avoiding public discourse and popular referendum). So the rest of us who aren't at Harvard or the University of Chicago pay the price for their reindeer games. All I have to do is look at my home town of Wichita to see the causalities of all this.

Depends if you consider only your nation and your people important. If you place more value in humanity itself, then free trade puts the benefits of corporations and humanity before the benefit of nations.

Corporations exist only because of the legal fiat of "nations" (nation states, anyway).

But, certainly not. Mercantilism benefits corporations much more strongly. Diseconomies of scale can be mostly inhibited through a strategically designed trade and fiscal policy. Slower falling unit production costs and opportunities for price fixing abound, as the "nation" (well, non-aristocratic taxpayers, anyway) bears these costs. Nor do tariffs necessarily reduce unemployment. The mercantile firm may well decide to keep its selling prices stable at a markup (especially given its lower customer base) and just lay workers off in event of supply shocks or other.

Protection is a Faustian gambit for more rapid growth today at the expense of hulking inefficient corporations tomorrow. Corporations that would not exist without it.