At the outset let us say that "Libertarianism", as the term is used in current moral and political philosophy (as distinct from a view about freedom of the will), is the doctrine that the only relevant consideration in political matters is individual liberty: that there is a delimitable sphere of action for each person, the person's "rightful liberty," such that one may be forced to do or refrain from what one wants to do only if what one would do or not do would violate, or at least infringe, the rightful liberty of some other person(s). No other reasons for compelling people are allowable: other actions touching on the life of that individual require his or her consent. In the course of this study the idea will get some refinement. But it is always refinement of that idea, rather than some hybrid or evolutionary version.
(Jan Narveson, The Libertarian Idea [Orchard Park, NY: Broadview Press, 2001], 7 [first published in 1988])
Keith Burgess-Jackson, J.D., Ph.D. 