Monday, January 26, 2009

Locke and the idea of the void

In the seventeenth century, the two dominant forms of mechanistic philosophy were Cartesianism and corpuscularianism. The former denied the possibility and hence existence of the void, and the latter affirmed the existence of the void, since matter was ultimately discrete.

Locke, being much in favor of corpuscularianism over Cartesianism (though withholding belief about whether corpuscularianism delivers scientia about natural bodies), surely must have wondered how it is that one can have an idea of a void.

I’ve wondered whether this passage from the Essay could have been deployed by Locke to explain the idea of a void.

“If it were the design of my present undertaking to enquire into the natural causes and manner of perception, I should offer this as a reason why a privative cause might, in some cases at least, produce a positive idea, viz. that all sensation being produced in us only by different degrees and modes of motion in our animal spirits, variously agitated by external objects, the abatement of any former motion must as necessarily produce a new sensation, as the variation or increase of it; and so introduce a new idea, which depends only on a different motion of the animal spirits in that organ (II.viii.4).”


tpy said...

Bayle's reading of Locke on the vacuum:

"Mr. Locke (2.13) believing that the could not define what a Vacuum is, hath yet given us clearly to understand that he took it for a positive Being. He had too clear a Head not to discern that Nothingness cannot be extended in length, breadth, and depth."
- "Zeno" F∆∆ (in English edition)

If Locke thought the void was a positive thing, then what Lockean principle getting in the way of our having an idea of it? Why would we need a privative cause for our idea of space?

Or were you suggesting that Locke did not consider empty space to be a thing?

Dan said...

Hi, Tim. As usual, great question...

I’m thinking of the section where he talks about solidity. He asks us to consider whether it makes sense to conceive of an object moving while everything else in the universe is at rest (which he thinks is distinct from imagining that such a body really exists in the actual world). He thought it makes sense to conceive of this. He calls the area that the object deserts “pure space.” I’m not sure that Bayle is right in taking Locke to think that was a positive being. It’s not a substance in any sense, especially if Locke is exercised to distinguish such a pure space from body as such (contra the Cartesians).

In fact, Locke wrote a letter (or was it a journal entry?) in the late 1670s where he said that space should be considered as merely a possibility or capacity for bodies to exist in place-designations. So, I think that it makes sense to take Locke to be a relationalist about space.

tpy said...

That's interesting. Do you think he possibly migrated from relationalism to substantivalism after his reading of Newton and later acquaintance with him? Perhaps there is a shift in his thinking (like in the late 1680s).

I can't find it offhand, but I thought in a letter to Shaftesbury he made some mention of holding a Newtonian view, but I'll defer to you on all matters of Locke.

Dan said...

Well... you might be right. No one would accuse Locke of either never changing his mind or being entirely self-consistent.

If you find evidence that Locke migrated to substantivalism about space or that he was ambivalent about the nature of space, please send it along!

tpy said...

Just found Letter 2395 to van Limborch (Feb, 1698) in which Locke makes frequent reference to the infinite extent of space. It comes in an argument for there being only one God, so it is not clear that he actually holds to an infinite space. But if he is thinking of space as wherever God is, and God as necessarily existing, he may be more than a relationalist about space. However, he doesn't make any direct argument in this passage from God's immensity or omnipresence to the existence of space, so I'm not inclined to draw too much from it.