To: Christian M.
From: Geoffrey Klempner
Subject: Defence of Locke's view on real and nominal essences
Date: 1st April 2008 11:21

Dear Christian,

Thank you for your email of 20 March with your University of London Modern Philosophy 'free' essay in response to the question, 'Is nature "pre-packaged"? -- A defence of Locke's distinction of real and nominal essence.'

This is a superb essay. I would have liked to have known your other sources besides Ayers and Locke, as the argument is of a level of sophistication which implies (to me) that you have read quite widely. The Kripke/ Putnam view of natural kinds would be an obvious example.

There is so much to say. First, the context of the debate (I don't have Ayers to hand but I guess that he refers to this) is J.L. Mackie's resurrection of Locke's account of real essence in his book 'Problems from Locke'. Some earlier abridged editions of Locke actually had the important passages removed. To students (like myself) who were reading the unabridged version of the Essay, Mackie's book came as a revelation.

The traditional interpretation of Locke saw him very much through the eyes of Berkeley, and wrongly identified 'real essence' with the conception of substance which Locke ridicules with the story of 'what the earth rests on' (and the infinite regress which that generates). Mackie reads Locke in the light of Kripke and Putnam, as recognizing the importance of an indexical aspect to the classifications that we make (the point you make with the two varieties of gold).

In an important sense, Locke is right and Aristotle was wrong. That's the crucial point. Locke takes the empirical view of real essence. We seek to adjust nominal essences to our conception of description of the world which provides the best explanation for the varieties which we find in nature -- something which science seeks to discover. This is a major 'interest', although not necessarily our only interest in making classifications.

Aristotle's view of essence, by contrast, has to be understood against the background of his implacable hostility to atomism and the idea of the possibility of micro-structural explanation (e.g. in 'On Generation and Corruption'). In Aristotle's view, human reason and the exercise of sense perception ought to suffice for understanding the world in which we find ourselves. The idea that there might be something forever beyond our knowledge -- imperceptible 'atoms' -- was totally unacceptable. Hence, Aristotle gives Platonic view of essence, as something ultimately given as a metaphysical fact. Water freezes and boils because that is just what the ultimate nature of water is, that is its essence. In respect to this archaic view, anyone today would count as a 'nominalist', including (I hope) Ayers.

Modern attempts to resurrect Aristotle have concentrated on the importance of micro-structural explanation to sortal concepts (such as 'man' or 'horse') which underlie our ability to identify spatio-temporal particulars. You will find this in David Wiggins' fascinating book 'Sameness and Substance', an expansion of his earlier, 'Identity and Spatio-Temporal Continuity'.

This is where your speculations about worlds where things are as Locke thought they might be on a micro-structural level -- indefinite variability rather than the 'pre-packaging' which we find in our world -- really bite. It seems a merely contingent fact that we inhabit a pre-packaged world rather than a variable world. The problem, however, is that a truly variable world would be one where it was difficult, if not impossible, to provide adequate criteria for spatio-temporal continuity.

From the standpoint of metaphysics, of course one wants to be able to provide a description which is to a large extent independent of mere contingencies. But at least in this respect, the very nature of particulars (in the sense described in Strawson's seminal work 'Individuals: an essay in descriptive metaphysics') does seem to depend on a remarkable contingency, namely the contingency which makes it possible to identify particulars in the way that we do, as examples of natural kinds.

The idea that borderlines between kinds may be fuzzy and don't have to be sharp goes with the empirical view of real essence. The world is messy. There are varieties of ways in which we collect things together in order to explain their properties as flowing from an underlying identity of structure. This idea, however, would be unacceptable to Aristotle. Form is given as a metaphysical fact, that which divides things into given kinds and makes classification possible. There would be no reason or logic in overlapping, clustering or indistinct forms.

One point from Ayers does remain: Locke didn't know what we know, and therefore wasn't in the position to state that the world is, in fact, nicely pre-packaged in all sorts of ways. However, given this, it is all the more remarkable that Locke described a view of essence which goes perfectly with what we know now about biology, chemistry and physics.

All the best,

Geoffrey