Hobbes and Newton on the co-constitution of bodies and minds

The definition, therefore, of body may be this, a body is that, which having no dependence upon our thought, is coincident or coextended with some part of space...they answer best that define an accident to be the manner by which any body is conceived; which is all one as if they should say, an accident is that faculty of any body, by which it works in us a conception of itself. --Hobbes, Elements of Philosophy, Concerning Body, Part Second, chapter 8 "Of Body and Accident" [HT Jennifer Jhun]

In what follows I use 'Hobbes' as shorthand for his Elements of Philosophy. (I, thus, ignore any other works by Hobbes.) Because Hobbes is a quintessential modern corpuscularian, and we are often told that the encounter with Galileo was decisive to Hobbes' life it is natural to read passages like the one just quoted as instantiating a primary/secondary quality distinction, especially because Galileo seems clear on the distinction in (say) The Assayer. (See Martha Bolton's lovely review essay in the Stanford Encyclopedia.) Hesitation on the ascription of the primary/secondary quality distinction to Hobbes immediately creeps in (not just because Bolton does not mention Hobbes, but also) because in (the quoted passage from) Hobbes it seems nearly all qualities of bodies are what one might call 'secondary' and only the bare bodies themselves, and perhaps magnitude (as being the quality body shares with extension or parts of space), are what one might call 'primary' if it wouldn't be so odd to call body itself a quality of (ahh) body. 

A Hobbesian accident may be thought of as a disposition or relational quality (as Jhun suggests in the paper that triggered this post). In particular, it is a quality of body that is intelligible to us (assuming that if we an have a conception of it, it's intelligible). There is an interesting question lurking here to what degree accidents are co-constituted by the conceptions of agents. And, so, it seems that for Hobbes there is a bare and parsimonious absolute ontology of fairly homogeneous matter, and that the rest of nature's structure or differentiation is, in part, the effect of the conceptualizing existence of material minds like ours.*

So, if Hobbes has or anticipates a primary/secondary quality of bodies distinction at all (which I am doubting), the list on the primary side is going to be rather short (it seems to include only magnitude or extension, which Hobbes explicitly treats as synonyms "The extension of a body, is the same thing with the magnitude of it, or that which some call real space.")+ And the list of secondary qualities will include features that are generally taken to be primary in the early modern tradition. For example, in the same section Hobbes goes on to write: 

[T]here are certain accidents which can never perish except the body perish also; for no body can be conceived to be without extension, or without figure. All other accidents, which are not common to all bodies, but peculiar to some only, as to be at rest, to be moved, colour, hardness, and the like, do perish continually, and are succeeded by others; yet so, as that the body never perisheth. [emphasis in Hobbes]

So, Hobbes does have a distinction between universal or what one may call 'intrinsic' or 'essential' qualities of body -- these are the accidents that make a body a body while it exists -- and non-universal or extrinsic or inessential qualities of body. Now, as readers of Newton's third rule of reasoning know, there is no necessary requirement to treat universal qualities as intrinsic qualities of bodies. That a quality is a universal property of matter may be an accidental feature of the universe; God's will or the laws of nature could have been otherwise. But it looks like Hobbes tacitly denies any gap between the universal and intrinsic qualities of body. And that makes sense, because Hobbes' list of these is incredibly short: only extension/figure is universal to body, and it must intrinsic to it.

Again, one may well treat the distinction between features of body that never perish except when the body perishes and features that are transient qualities of bodies as a kind of anticipation of the primary/secondary quality distinction. And I think that's fine, as long as one remembers that the transient qualities of bodies include accidents that are often treated as primary (hardness, motion/rest) by the rest of the tradition.

The significance of this is two-fold. First, relative to Galileo, Descartes, Boyle, and Locke, Hobbes is really an outlier. But, second, I do think pre-Principia Newton toyed with something close to Hobbes' position. This seems to be suggested by an extended aside in Newton's manuscript known as 'De Grav.' (I call it an 'aside' because it both detracts from the main argument of De Grav, and, in fact, is in some tension with it, or so I have argued.) After articulating the exceptionally clear idea of space, Newton offers a tentative hypothesis on the nature of body with an extended thought experiment involving God's creation. I quote the crucial passage from Andrew Janiak's edition:

And hence these beings will either be bodies, or very similar to bodies. If they are bodies, then we can define bodies as determined quantities of extension which omnipresent God endows with certain conditions. These conditions are: (1) that they be mobile, and therefore I did not say that they are numerical parts of space which are absolutely immobile, but only definite quantities which may be transferred from space to space; (2) that two of this kind cannot coincide anywhere, that is, that they may be impenetrable, and hence that oppositions obstruct their mutual motions and they are reflected in accord with certain laws; (3) that they can excite various perceptions of the senses and the imagination in created minds, and conversely be moved by them...--Newton's Philosophical Writings, edited Janiak, p. 43

To be sure, this is not exactly Hobbes' position. For, Newton does not rely on Hobbes' terminology of 'accidents'. Hobbes would not define body as determined quantities of extension (let alone let God's will play such an outsized role).  And it does seem that Newton is inclined to treat mobility and impenetrability as universal qualities of bodies, where Hobbes would not. But here in (3) Newton does echo Hobbes in thinking that except for the spatiality of body, it is rather to central to body (I almost wrote 'intrinsic to body') as such that body has a relationship to minds. 

Now, again there are important differences between Hobbes and Newton even on this point. In Newton this relationship is causal: bodies can "excite various perceptions of the senses and the imagination," whereas in the passages quoted from Hobbes the relationship is conceptual, we cognize features of bodies which, thereby, become intelligible if not differentiated. (Of course, there are plenty of passages in Hobbes, in which our thinking is treated in terms of the effects on the senses by bodies in motion!)

This soft connection between Hobbes and Newton is not wholly contingent. We know from Newton's early notebooks that Newton read De Corpore, and that he reacted strongly against Hobbes' materialism. And so while I don't want to claim that Newton was self-consciously following and modifying Hobbes (and Newton's position evolved away from  the one presented De Grav), I do want to claim them as occasional partial fellow-travelers when it comes to analyzing bodies as spatialized, in one absolute sense, and as treating the differentiating properties of bodies as being more than accidentally linked to minds that perceive or cognize them. 

*This anticipates some of (the as it were formal structure of) Spinoza's metaphysics, although because of Spinoza's commitment to infinite attributes the details are going to be very different.

+In "Hobbes and the Phantasm of Space," (2014) Ed Slowik nicely brings out the bewilderment one might feel if one reads Hobbes and comes to it with the primary/secondary quality distinction.

Comments

[Bill Wringe]

‘That which having no dependence on our thought is coincident or coextended with some part of space’ - why wouldn’t a shadow count as a body on this account?

[ERIC SCHLIESSER]

I suspect the definition also includes a silent 'and has volume' (since space has dimensions). But perhaps it's the coloration of shadows that puts them in the accident category.