Isaiah Berlin argues in his essay, “Two Concepts of Liberty,” (which is based on the lecture that he gave before the University of Oxford on 31 October 1958), that there are not one but two concepts of liberty—positive and negative. He also notes that liberty is a porous concept “with more than two hundred senses of it recorded by historians of ideas.” Here’s an excerpt: “To coerce a man is to deprive him of freedom – freedom from what? Almost every moralist in human history has praised freedom. Like happiness and goodness, like nature and reality, the meaning of this term 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.” Immanuel Kant was probably the first philosopher to distinguish between a negative and positive sense of the term “liberty”. Berlin is essentially defending a Kantian view of liberty in his essay—he shows that positive and negative liberty are not only distinct, they can also be seen as the opposing and incompatible expositions of the same political ideal.