I posit instead that libertarianism is a means of interpreting a political philosophy.
That said, libertarianism does have a number of foundational principles. They are:
- the non-aggression principle (NAP)
- the principle of self-ownership
1.) I sometimes explain the NAP as 'pacifism... with a catch'. Unlike true "turn-the-other-cheek" pacifism, the NAP is only a prohibition against initiating force or fraud. If PersonB is initiating violence (e.g. attempting to rob or murder) PersonA, PersonA is [in general] free to retaliate against PersonB. I say "in general" because to not say it is to oversimplify. For example, there is the issue of parity or proportionality.
2.) The principle of self-ownership appears in the abortion debate, having long been a refrain of the pro-choice crowd. For example: "Keep your laws off my body." One of the most well-known illustrations of the principle of self-ownership outside of the abortion debate is:
http://www.jonathangullible.com/mmedia/PoL.English.The.Philosophy.of.Liberty.swf
http://www.youtube.com/results?search_query=isil+philosophy+liberty
Beyond these foundational principles, there are also a number of facets of libertarianism (e.g. individualism vs. socialism, insistence on equal rights and equal protection of the laws). Beyond that, there are also 'related' topics, such as voluntaryism.
Notes: For the record, I am not a fan of the word 'libertarianism'. We "stole" that word from the socialists,* who used it first. Sure, it wasn't in much use at the time, but that's still no excuse. Our word is 'liberal', and that word was "stolen" from us by Progressives. Some have not abandoned the word 'liberal', and continue to refer to themselves as 'classical liberals'... to differentiate themselves from so-called 'modern liberals'.
*actual socialists... the fact that Republicans/conservatives have repurposed that word to describe Democrats/Progressives upsets me
References and Further Reading:
http://www.huffingtonpost.ca/joyce-arthur/motion-312_b_1525263.html
http://www.nationalreview.com/corner/256269/keep-your-laws-my-body-jonah-goldberg
http://www.coyoteblog.com/coyote_blog/2012/02/keep-your-law-off-my-body-err-or-maybe-not.html
http://reason.com/archives/2010/03/04/keep-your-laws-off-my-body
