"We are witnessing a return to the antagonistic protectionist politics that defined a bygone era that ended with World War I — suggesting that today’s protectionist revival threatens not just the global economy, but world stability and peace.
Leading liberal democracies have turned their back on free trade. Britain, through Brexit, announced its retreat from European market integration. Before the parliamentary elections, British Prime Minister Theresa May announced a new Industrial Strategy, which includes state subsidization of select industries and stringent immigration restrictions on foreign workers at “every sector and every skill level.”
"in the recent French presidential elections the vast majority of candidates ran on a platform of “patriotisme économique.” Marine Le Pen, leader of the French far-right National Front party, made a strong bid for the French presidency through a campaign that combined a condemnation of globalization alongside the promise of extreme economic nationalist legislation and an end to immigration into France."
"“Free trade’s no good” for the United States, as Donald Trump put it in 2015. President Trump has threatened to shred the North American Free Trade Agreement and to impose protective tariffs on imports from Mexico and China"
"This widespread fear of the global marketplace and the looming threat of tit-for-tat trade wars herald a return to late 19th-century geopolitics. Then, too, many of the leading economies of the day took shelter behind high tariff walls to halt the forces of globalization. Following the onset of an economic depression in the early 1870s, one industrializing country after another turned against trade liberalization. Trade wars, colonialism and closed markets became the name of the geopolitical game.
In stark contrast to today, back then only Britain stuck to free trade with “all the world.” Yet even free-trade bastion Britain was not without its domestic economic nationalist enemies."
"“Fortress France” turned away from free trade in 1892, the culmination of a decade-long “protectionist backlash” to the ongoing economic depression. The protectionist measure exacerbated the Franco-Italian trade war, which Italy had started with its turn to protectionism in the mid-1880s. Trade between these countries fell considerably, pushing Italy ever closer to Austria-Hungary and Germany — the Triple Alliance — in the years before the First World War.
The United States, however, topped the list of protectionist states. The political and ideological power of protectionism in late 19th-century America — the Gilded Age — was palpable. The Republican Party, formed as the party of antislavery in the 1850s, fast remade itself as the party of protectionism following the Civil War.
Hoping to protect U.S. industries from the unpredictable gales of unfettered global market competition, the ultranationalist party tacked its sails to the “American System” of high tariffs and government subsidization of domestic industries."
"late 19th-century U.S. free traders argued that trade liberalization fostered international stability and peace, and that, by contrast, the era’s global uptick in imperialism and war only illustrated how protectionism fomented geopolitical rivalry and conflict."
"The protectionist resurgence among the leaders of post-1945 globalization — be it Brexit, patriotisme économique, or “America first” — holds dire consequences for the liberal economic order by pitting nations against one another and breeding suspicion, distrust and conspiratorial thinking. The ultranationalism, militarism and tariff wars of the late 19th century spilled over into the 20th century, and ended in world war — suggesting a return to the protectionism of old could damage far more than national economies."
Less trades means less exchanging of ideas, culture and technology, in addition to goods. Then maybe countries start to develop an "us vs. them mentality" and it becomes easier to demonize the other side, which can lead to war.
Trade can benefit both sides. Otherwise, why make the trade? For example, if you have bread and no water and I have water and no bread, if I trade some water to you for some of your bread, we both gain or are better off.
It might seem like if one country is "better" at producing all goods than another, they have no room for trade. But even then, the seemingly more advanced country will sill gain from trade.
Here is an example that comes from the early 19th century economist David Ricardo, who came up with the idea of "comparative advantage." That is when you can produce a good at a lower opportunity cost than others face (in a two good example, it is impossible to have the comparative advantage in both goods).
Suppose it takes 40 labor hours to make a barrel of wine in England and 2 hours to make a yard of cloth. In Portugal, those numbers are 10 and 1, respectively.
That means that if England wants a barrel of wine, it would have to give up 20 yards of cloth (since 40/2 = 20-if you don't produce a barrel of wine, you save 40 hours of labor and you can make 20 yards of cloth in that time).
In Portugal, if you want to trade a barrel of wine, you can get 10 yards of cloth. Not spending 10 hours making wine allows them to make 10 yards of cloth.
But what if England trades 15 yards of cloth to Portugal for 1 barrel of wine? Both countries gain. England is better of since they only give up 15 yards of cloth to get that barrel of wine when normally they have to give up 20.
Portugal gets more cloth (15 yards instead of 10) for that 1 barrel of wine they trade. They are better off, too (even though it takes them less time to make each product than in England).
So blocking trade across borders with tariffs will prevent beneficial trades from taking place.