Modern use of the term "libertarian" began with the "Who is a Libertarian" pamphlet, circulated by John Hospers in the 1960s. This FEE pamphlet contained a reprint of a 1955 article by Dean Russell, proposing the word "libertarian" to describe those who favor "Individual freedom with personal responsibility".
Russell began by saying, "Here is a suggestion: Let those of us who love liberty trade-mark and reserve for our own use the good and honorable word 'libertarian'" and noted that the dictionary already defined the word as, ""One who holds to the doctrine of free will; also one who upholds the principles of liberty, esp. individual liberty of thought and action" and added, "Strictly speaking, a libertarian is one who rejects the idea of using violence or the threat of violence -- legal or illegal -- to impose his will or viewpoint upon any peaceful person." Prof. Hospers apparently based his NAP (Non-Agression Principle) upon this notion.
Hospers circulated this pamphlet in the 1960s, long before helping David Nolan create the LP. I would also point out that, by these definitions, there are many millions of libertarians in the United States, but not all of them are in the party which adopted that name.
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