Sorry the Shorter OED doesn't have list the original citation. Perhaps
someone with access to the complete OED could help better. For what its
worth the shorter says:
Libertarian. 1789. [f. Liberty + ARIAN, after Unitarian etc] 1. One who
holds the doctrine of the freedom of the will. Opp. to necessitarian. Also
attrib. or adj. 2. One who approves of or advocates libertry 1878. Hence
Libertarianism, 1. principle or doctrinces.
ciao, patrick
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Patrick Wilken http://www.cs.monash.edu.au/~patrickw/
Editor: PSYCHE: An International Journal of Research on Consciousness
Secretary: The Association for the Scientific Study of Consciousness
http://psyche.cs.monash.edu.au/ http://www.phil.vt.edu/ASSC/