I’m currently reading Harvard psychologist and cognitive scientist Steven Pinker’s new book The Better Angels of Our Nature: Why Violence Has Declined. To read, it is at once a delight and an aggravation. But I’ll spare you the book review. For now, I just wanted to excerpt a particular passage relevant to this site:

In one of his pensées Blaise Pascal (1623-62) imagined the following dialogue: “Why are you killing me for you own benefit? I am unarmed.” “Why, do you not live on the other side of the water? My friend, if you lived on this side, I should be a murderer, but since you live on the other side, I am a hero, and it i just.” Voltaire’s Candide (1759) was another novel that slipped scathing antiwar commentary into the mouth of a fictitious character, such as the following definition of war: “A million assassins in uniform, roaming from one end of Europe to the other, murder and pillage with discipline in order to earn their daily bread.”

Together with satires suggesting that war war hypocritical and contemptible, the 18th century saw the appearance of theories holding that it was irrational and avoidable. One of the foremost was gentle commerce, the theory that the positive-sum layoff of trade should be more appealing than the zero-sum or negative-sum payoff of war. Though the mathematics of game theory would not be available for another two hundred years, the key idea could be stated easily enough in words: Why spend money and blood to invade a country and plunder its treasure when you can just buy it from them at less expense and sell them some of your own? The Abbé de Saint-Pierre (1713), Montesquieu (1748), Adam Smith (1776), George Washington (1788), and Immanuel Kant (1795) were some of the writers who extolled free trade because it yoked the material interests of nations and thus encouraged them to value one another’s well-being.

I would add another, Frederic Bastiat, who put it succinctly: When goods don’t cross borders, armies will.