Monday, September 16, 2013

Locke on primary and secondary qualities

To: Craig S.
From: Geoffrey Klempner
Subject: Locke on primary and secondary qualities
Date: 12th November 2010 11:56

Dear Craig,

Thank you for your email of 4 November, with your essay for the University of London BA Modern Philosophy: Descartes, Locke, Berkeley and Hume module, in response to the question, 'What role does the notion of resemblance play in Locke's account of the distinction between primary and secondary qualities? Is his account of the distinction a defensible one?'

Thanks also for your comments on my piece, In Pursuit of the Amoralist. My argument is 'Kantian' in the sense that I am looking for an a priori basis for moral judgement, but it also sharply diverges from Kant's view that we can derive a moral theory, the laws of ethics, by deduction from the Categorical Imperative. My approach is necessarily more modest.

The point you might have missed concerns the role of the statement, 'Other persons are not my measuring instruments'. I claim that this follows immediately from the idea that there is such a thing as truth. For the solipsist, there is ultimately no distinction between how I judge things to be, and how they are in reality. This is not as such a moral claim. Rather, the existence of other persons is a 'necessary condition for the possibility' of there being a notion of truth (to put the claim in Kantian terms). However, it follows that I cannot make a meaningful distinction between needs or interests depending on whether they are 'mine' or not. That is the minimum basis for an idea of moral conduct, but of course it still leaves much undecided.

Back to your essay.

Your sanguine defence of Locke had me searching my hard drive for an exchange I had with another of my UoL students on the same topic, back in March/ April 2006! We were looking for a quote which I seemed to remember from Locke's Essay to the effect that angels would be able to 'see' the corpuscles that constitute the gross bodies that we perceive. I think we did subsequently find the passage, although I don't have the reference to hand.

Let's say that angels have 'eyes'. How do they work? Evidently not by processing perceptual information acquired through a process analogous to the way our eyes work. (In theory, of course, they could but then we would be on the road to an infinite regress, with angels speculating about super-angels etc.) Let's assume the regress doesn't even get started: angels don't perceive through action at a distance on their sense organs. They interact directly with the corpuscles, feeling them, holding them, moving them in Helen Keller fashion, relying on proprioceptive feedback. That might work.

In theory, there is no reason why we need to have organs of sight, hearing, smell etc. Helen Keller-like beings could develop artificial tools for accomplishing what we are able to do by the gift of nature. A long time ago, I saw a piece on Tomorrow's World where a blind man was able to 'see' by means of a video camera which etched an image into his bare back by means of hundreds of needles. Ouch!

You claim that Locke's account is confirmed by science, but also, interestingly, argue that it would survive the discovery that 'mass, shape, size etc. turn out not to be the best way to understand matter. Locke's primary qualities would be unseated. Fair enough. We could abandon the term as outmoded or restrict it to properties deemed fundamental by current science.' Really? What reason do we have for holding that human beings, as a matter of logical necessity, have the capacity to acquire information about the world in a form which *represents* or *resembles* how things are, not just in the sense of structural isomorphism derived from theory, but in terms of content -- as our idea of, say, a spatial array is considered (still) applicable to particle physics?

The very next point you make is crucial here: 'Indeed 'solidity' was already dubious when Locke introduced it.' I say. It was in fact Leibniz who diagnosed the fundamental weakness in Descartes' account of material body. You can't derive physics from geometry alone. The extra something -- impenetrability, solidity, resistance to movement, mass -- all these notions are incapable of being derived from the idea of 'extension', where as in Descartes the visual sense is taken as the primary model perception.

On this account, if any property deserves to be called 'primary' it is the capacity to exert a force through physical contact. As a matter of logical necessity, any subject of experience must be capable of acting upon the world of their perception. Everything else, including the capacity for sense perception at a distance, is up for grabs.

Locke may have thought that it was sufficient to report on the 'best science' of his day. This science was itself the product of philosophy. Greek atomism played an important part, although Newtonian corpuscles are a very different animal from Democritean atoms. But the way he describes his distinction between primary and secondary qualities makes it look as though he has discovered a necessary truth about the very nature of perception, as it applies to any conscious subject in any conceivable physical world. That claim is wildly overstated.

All the best,

Geoffrey