Yuval Levin argues that our basic understanding of liberty today is wrong. Both liberals and libertarians see liberty as the absence of constraint, the liberty to do and to choose as one wants. He [Levin] suggests that Supreme Court Justice Anthony Kennedy's opinion in the 1992 abortion case Planned Parenthood v. Casey encapsulates the modern bi-partisan version of liberty: "At the heart of liberty is the right to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life." Opposed to what Levin calls this thin version of liberty (what is usually referred to as negative liberty) is a thicker liberty bound up in institutions that demands that individuals not only be free to choose, but that they be free to choose well. This, what is usually called positive liberty, assumes that we humans are not simply willful beings but that we are also rational, and that rationality means something. It contains standards and truths. For Levin, one element of this rational liberty of limitation is the family.