I gave you one reference as to Franklin acknowledging Vattel. Go there and I think you can find many more references. My take as to the Founders considering/incorporating Vattel is they took what They deemed good for the new Nation. Their Constitution, and ours, explicitly refers to ‘the law of nations’ in Sec. 8 of Article I. I consider this validating that the Founders were very much aware/atuned to Vattel’s works on government. I believe that Franklin being much connected to France and a power in the framing of the Constitution did much to have the Founders knowledgeable about Vattel’s views of government.
Such a conclusions would simply be inaccurate.
The "law of nations" was a general category of law, and it was by no means the sole province of Vattel. He was simply one of quite a few different writers on the subject.
It's like saying that if Vattel wrote a book titled, "Right to Bear Arms," and the Constitution refers to our right to keep and bear arms, then that means the Founding Fathers were fans of Vattel's book and his philosophy, and therefore there is no individual right to keep and bear arms.
The example is fictional, of course (Vattel wrote no such book) but it illustrates what I'm saying. The "law of nations" was a GENERAL topic, a general area of law. And there is NOTHING to suggest that when the Framers referred to the "law of nations" in our Constitution, that they were referring to Vattel or his book.
Actually, if you want to go there...
What they referred to, quite specifically, was "OFFENSES AGAINST THE LAW OF NATIONS."
There IS a book that uses VIRTUALLY THAT IDENTICAL PHRASE as the title of one of its chapters.
The chapter title is: "OF OFFENSES AGAINST THE LAW OF NATIONS."
The book was EXTREMELY well known in the Founders' and Framers' day. The book that I refer to was far better known, far more used, and far more quoted, by the Founders and Framers, than Vattel's book EVER was.
That being the case, would you agree with me that this book, with its chapter entitled, "OF OFFENSES AGAINST THE LAW OF NATIONS," is most likely where they got the phrase from?
One link directed me to Jefferson's library, and to George Washington having borrowed a copy of Vattel's LON and never having returned it, all of which I was familiar with.
Like I said: It's clear that the Founding Fathers read Vattel. It's clear that they paid attention to him in areas of international law. But there's nothing to suggest they paid much, or even ANY, attention to him on matters of how to define citizenship. And again, even on the law of nations, he was only ONE writer of quite a few.
If you look at Jefferson's library, it has Vattel's book. It also has "law of nature and nations" books by Beller, Cumberland, Burlamaqui, Perreau, Ward, Grotius, Puffendorf, Wolff, Martens, Rayneval, Felice, Barbeyrac, Lee, Selden, Bynkershoek, and others.
Yes, Vattel was an important writer on the law of nations. But he was far from the only one.