 Unfortunately, having laid down this requirement, Locke complicated matters by adding a substantive principle of respect for private property: “The Supream Power cannot take from any Man any part of his Property without his own consent”, and any law that purports to do so is of no validity (Locke 1689: §138). But then there is a difficulty. Though Locke gave us his own theory of prepolitical property rights—the so-called “Labor Theory” in Chapter Five of the Second Treatise—it was itself far from uncontroversial. People in our day, as in his, disagree about the rival claims of labor and occupancy; they disagree about the background of common ownership; and they disagree about how much anyone may appropriate and how sensitive his appropriation must be to the needs of others. We disagree about all that—in ways that were made evident, for example, in the debates about the Lockean theory of Robert Nozick (1974). And Locke and his contemporaries disagreed too; Locke knew, and signaled in a number of places that he knew just how controversial all this was (Tully 1980: 64 ff; for Locke’s awareness of the controversies, see Waldron 1999: 74–5).