Libertarianism: a definition

I’ve been musing, over the past few months, about what exactly I mean by libertarianism, and trying to come up with a concise definition. I have now, at last, come up with a first draft. Please feel free to question, comment, or critique.

Libertarianism: the philosophy that holds that the ultimate political value is the freedom of the individual, and that the most effective way to uphold that freedom is to limit the scope of the state to those activities which directly defend that freedom.