The Philosophy of Loyalty by Josiah Royce (1908)
How embarrassing... I overlooked this cornerstone of American ethical philosophy when I worked for FL. Now I'm studying it in my ethics class. Ah well, 20/20 and all that.
This philosophy would be a healing balm for the division and dramatic polarization we're seeing in the West today. It's an approach to ethics, not strictly speaking an ethical system unto itself, but it enables the discourse necessary to attain ethical common ground in a pluralistic society. Well worth reading and would be incredibly inexpensive to produce as a Logos ebook (though it properly fits under the Noet LOB).
https://archive.org/details/philosophyloyal00roycuoft
The Philosophy of Loyalty
Josiah Royce (1855-1916)
Macmillian, 1908 (public domain)
~400 pages