The central task of this dissertation is to develop a new interpretation of Leibniz's famous claim that there are no purely extrinsic denominations . Though Leibniz regarded NPE as one of his most important doctrines, he nowhere offers an explicit statement as to what he meant by it. One interpretation of NPE, which enjoys a modest consensus among interpreters, is that all extrinsic denominations reduce to intrinsic denominations. According to the reductionist view, things only have intrinsic denominations as properties; extrinsic (...) denominations are not genuine properties of things. Critics of reductionism have argued that the textual case for it is inconclusive at best, and I share this assessment with them. However, in my opinion, a satisfactory non-reductionist understanding of NPE has not been offered. The goal of my dissertation is to provide such a non-reductionist account. I contend that NPE, far from being a claim of the reducibility of extrinsic denominations, is actually an assertion that extrinsic denominations are genuine properties of the things they denominate. ;To establish my reading of NPE, I examine a line of textual evidence to which interpreters have paid little attention: the way Leibniz argues for NPE. In some passages Leibniz derives NPE from his predicate-in-subject principle of truth. In others, he employs his doctrine of the interconnection of all things to reach NPE. Elsewhere, he bases NPE on the principle of the identity of indiscernibles. Though, as mentioned, Leibniz never explicitly defines NPE, he does have much to say by way of explicit definition of each of these three principles. A consideration of what version of NPE could plausibly be drawn from them is thus a revealing way to proceed. In the case of each argument, I show that my interpretation of NPE is the conclusion naturally suggested by the given principle, while the reductionist version of NPE forms only an awkward, textually implausible fit with it. The result of the examination is an original and serious critique of the reductionist reading of NPE, as well as the development of a far more plausible understanding of that claim. (shrink)