Allison Kuklok

I argue for an interpretation of Hume on which our confused notions of causal necessity find their model in Hume's notion of logical necessity: our minds react in similar ways to constant conjunctions, on the one hand, and genuine cases of inseparability between ideas, on the other, in light of which we mistakenly place relations of necessitation between objects we call cause and effect. I argue that my account provides a more satisfying explanation of the mismatch between the feeling that provides our true idea of necessary connection and the confused notions of necessary connection held by philosophers and the vulgar.

When I classify Fluffy as a cat, I appear to do so out of an appreciation of a prior metaphysical fact, namely, that she has a nature or essence common to creatures we classify as cats. Locke turns this picture on its head. Our actual practices of naming and sorting individuals into kinds proceed according to ideas in the mind. As Locke puts it, species (kinds) are ‘the Workmanship of the Understanding,’ not the workmanship of nature, because their essences consist in abstract ideas, or ‘nominal essences,’ we make. Many take Locke to mean that the observable similarities and differences between things leave it undetermined how we are to group and distinguish them, so that classification is, and must be, a matter of convention. And while Locke never denies that individuals have real essences, it is argued that knowledge of them would not reveal natural boundaries, either. On this influential reading, nature does not draw boundaries between kinds, and she makes this fact apparent to us. I argue that Locke’s claim that nature does not determine the ‘Boundaries of the Species of Things’ should be understood as the claim that nature does not draw the variable boundaries set out in the nominal essences we make. Differences in our nominal essences reflect differences in speakers’ knowledge of external ‘standards,’ which we latch on to by way of their ‘leading’ qualities, which present the mind with a limited number of unique and highly salient bases for classification. On my reading, nature may very well draw boundaries of her own.

I argue that Locke’s various descriptions of real essence pick out one and the same thing, namely a nature that can be ascribed to many things, and in terms of which we can get matters of classification right or wrong. On my reading, Locke does not attack real essences of the sort that are the essences of real species, but rather the presumption that a sorting according to our species concepts and their names is a sorting of things according to their real essences. And the lesson of Locke’s empirical argument against that presumption, I argue, is that our species concepts often function more like higher taxa, grouping together things that knowledge of their real essences would distinguish into distinct lowest species.

It is often claimed that classification, on Locke’s view, proceeds by attending to similarities between things, and it is widely argued that nothing about the sensible similarities between things determines how we are to sort them, in which case sorting substances at the phenomenal level must be arbitrary. However, acquaintance with the “internal” or hidden qualities of substances might yet reveal objective boundaries. Citing what I refer to as the Watch passage in Locke’s Essay (henceforth Watches), many commentators claim that classification at the microphysical level must also be arbitrary. They conclude that sorting is arbitrary at any level of description. I refer to this as the standard reading of Locke on classification. In this paper I argue that Locke does not claim that sorting is arbitrary, either at the phenomenal level, or at the microphysical level. First, Locke does not claim in Watches that sorting is arbitrary at the microphysical level. The existence or nonexistence of objective boundaries at the microphysical level is not Watches’ topic and the passage is in fact silent on that question. Here, the standard reading mistakes a claim about the nature of the task of locating “specific differences” for a claim about the nature of the task of classification. This diagnosis proves instructive, for I argue that a similar conflation underwrites the standard reading’s claim that sorting at the phenomenal level must be arbitrary. Far from arbitrarily choosing how to sort things in terms of their phenomenal similarities, Locke thought that the mind simply follows nature’s lead. This characterization of the mind’s activity, I go on to argue, accords well with Locke’s claim that species are the workmanship of the understanding.

Locke's Essay Concerning Human Understanding is considered by many to be the locus classicus of a number of influential arguments for conventionalism, according to which there are no objective, privileged ways of classifying things in the natural world. In the dissertation I argue that Locke never meant to reject natural kinds. Still, the challenge is to explain how, within a metaphysics that explicitly denies mind-independent essences, we can make sense of a privileged, objective sorting of substances. I argue that we do so by looking to Locke's conception of God as divine architect of created substances