Holly Metcalf Kinyon's 1776 broadside printing of the Declaration of Independence at the Museum of the American Revolution in Philadelphia. Metcalf Kinyon, a descendent of Declaration signer John Witherspoon, has lent her document to the museum. (Matt Rourke)
J.M. Opal is chair of the department of history and classical studies at McGill University and author of “Avenging the People: Andrew Jackson, the Rule of law, and the American Nation.”

In the age of “America First,” it’s easy to remember July 4 as the day we Americans resolved to go it alone. As Thomas Jefferson proclaimed in the Declaration of Independence, the people of the 13 colonies had “totally dissolved” their ties to the British Empire and could henceforth do whatever “Independent States may of right do.”

But who told Jefferson what states could rightly do? Where did his notions of national self-determination come from? And why did he and other founders believe that their fragile new country could assume a “separate and equal station” on Earth without being gobbled up by hostile powers?

The clearest answer is someone few Americans have ever heard of: Emer de Vattel. Swiss by birth but mostly employed in the Holy Roman Empire, he was an authority on the “law of nations,” the 18th-century term for international law. He never lived to see the new United States — he died in 1767 — but his influence on American thinking was as deep and direct as it is now forgotten.

Vattel’s ideas came out of his mountainous homeland, a multilingual confederation of towns and duchies surrounded by bigger and stronger states. His desire to preserve Swiss liberties led him to embrace the treaties and borders that made Europe a patchwork of different nations — a larger version of Switzerland, in some respects.

The idea of keeping a balance of power was nothing new. But Vattel rejected the corollary assumption that the world was a jungle where only the strong deserved to survive. Such ideas were “detestable,” he wrote.

According to Vattel, people were made to join for safety and happiness. Society was their natural habitat. And in the more enlightened age he saw around him, where violence and tyranny seemed to be waning, modern nations made up a “great society” in which every country, like every man, was “naturally equal.”

“A dwarf is as much a man as a giant,” Vattel reasoned. Thus, “a small republic is no less a sovereign state than the most powerful kingdom.” Each was free to pursue its happiness, so long as it respected that freedom among others, lived up to its treaty obligations and showed compassion for the poor, sick and helpless. Nations could also break away from negligent or abusive rulers. For details, interested parties could consult his lengthy tome, “The Law of Nations,” first published in 1758.

Americans, it turned out, were quite interested, especially after years of futile protest of British policy during the 1760s and early 1770s.

In 1775, Benjamin Franklin turned to Vattel’s book as a kind of beginner’s guide for countries. He even secured a copy for the Continental Congress, reporting in December that it was “continually in the hands of the members” as they scrambled to set up a working government. Jefferson almost certainly consulted it while drafting the Declaration in June of 1776; some of its most famous lines paraphrase Vattel.

After the Revolution, Federalists such as Alexander Hamilton used “The Law of Nations” to protect former loyalists and gain respect in London, while their Jeffersonian foes cited Vattel to condemn the British Empire’s ongoing mistreatment of the former colonies. They were both right. Vattel opposed bullying, whether by great powers on the world stage or by angry majorities within a society. He also expected “generous nations” to treat foreign prisoners decently, and during the War of 1812, U.S. leaders of all stripes generally respected that standard, too.

Americans of the early republic read Vattel because they wanted to believe in the world he described: a society of nations, not a Hobbesian jungle. They embraced international law as a duty and privilege of nationhood. In a republic, one of the first Supreme Court justices opined in 1790, “the law of nations is the law of the people.”

None of this makes Emer de Vattel a “real” Founding Father. Nor does it mean we should accept his ideas uncritically, as several members of the current court would have us do with the framers of the U.S. Constitution.

After all, Vattel showed little interest in half the human species (women). He was dangerously ignorant of Native Americans, asserting that since they didn’t farm (some native women farmed) they had no right to their lands. After winning fame in the second war with Britain, Andrew Jackson used “The Law of Nations” to demand the destruction of “savage nations” and escaped slaves in Florida. Then as now, people weaponized ideas to suit their desires.

So the lesson is not that we should enshrine Vattel and his ideas. Rather, it’s that the American Revolution was as much about joining an international society as it was about seceding from the British Empire. Refusing second-class status under the Crown, the patriots put their faith in a Vattelian world of human progress and decency, a place where at least some nations would be treated equally.

On this Independence Day, in particular, that’s worth celebrating.