Two Concepts of Liberty/porous
From Critiques Of Libertarianism
Almost every moralist in human history has praised freedom. Like happiness and goodness, like nature and reality, it is a term whose meaning is so porous that there is little interpretation that it seems able to resist. I do not propose to discuss either the history or the more than two hundred senses of this protean word recorded by historians of ideas.
Isaiah Berlin, "Two Concepts of Liberty"