In the background lurks, again, the legacy of an extreme form of dualism. Latour likes to refer to it as ‘the modern constitution’; a more common genealogy derives it from the philosophy of René Descartes. He held that the mind and the body are two ‘distinct substances’. The body is extended in space and constituted of parts that can be sliced off and removed like cogs from a machine, in starkest possible contrast to the thinking mind. If a heart is cut out from a body, that body loses a vital component and ceases to be – but where is the heart of the mind? Where are its arms, its legs, its constituent parts potentially separated from each other? They are nowhere, Descartes argued, for the mind is a thing one and whole, indivisible, indestructible; it does not possess a corporeal shape. The body is a physical substance, but the mind is an ethereal, spiritual sort of thing. This is why the mind can live on and prosper without the body; after death and decomposition, it survives because it is made of utterly different stuff. ‘Two substances are said to be really distinct’, Descartes lays down his central criterion, ‘when each of them can exist without the other’: and here such is the case, Descartes being ‘certain that I am really distinct from my body and that I can exist without it’.12 His philosophy is a substance dualism.
In the debate on nature and society, critics of Cartesianism are in the habit of mapping that philosophy onto the pair.13 Descartes himself did not speak in terms of these categories – his concern was the problem of body and mind – but many observers have found in Western worldviews the fingerprint of that philosopher, his dualist model simply extended to the analogous realms. And, indeed, the all-too-common conceptual segregation of nature and society can be seen as its logical continuation. If only by default, rather than some explicit alignment with Descartes, a characteristically Cartesian view of nature and society treats them as distinct substances fundamentally detached from each other. There might be occasional interstellar traffic between them, through some tiny pineal gland, but their essences are of opposite kinds and move in separate orbits.
Now, hybridism screams out its hostility to Cartesianism from every page it commands. It poses as the absolute negation of that obnoxious philosophy, since it refuses to countenance any distinction whatsoever between nature and society, to the point of denying their existence. That latter move, however – that rush to jettison the categories as soon as the extent of their entanglement comes into view – is, at a closer look, merely the flipside of substance dualism. Descartes himself spelled out its corollary: ‘to conceive of the union of two things is to conceive of them as one thing’.14 Anyone who believes that the body and the mind form a union would, he argued, be forced to recognise them as an undifferentiated oneness. By taking observations of their combination as so many reasons to expunge nature and society from the map of the world, hybridism updates this logic for our times. Moreover, it draws all of its rhetorical force from centuries of Cartesian thinking, to which the quantitative, historical component stands in exact proportion, the surprise at the proliferating combinations emanating from the legacy of extreme dualism: of this thinking, hybridism is not so much a rejection as a consequence. It is a negation of it only in the way the hangover is a negation of the binge. It is post-Cartesian in the sense that some scholars are post-Keynesian or post-Kantian: they carry the code of the original creed within themselves, if only in diluted form. Hybridism is to Cartesianism what e-cigarettes are to cigarettes.
HISTORICAL MATERIALISM IS A PROPERTY DUALISM
The mind, according to Descartes, is nowhere. It does not occupy any location in space. The substance of which it is made is not the kind that sits on a stool or lifts a weight or kicks a stone; it is defined precisely by not having extension, of being altogether otherworldly, cut off from mortal flesh. This philosophy gives rise to a well-known problem: that of causal interaction. If a stone is kicked down a path, it is because some foot has come into contact with it at a place. The foot has imparted motion to the stone, causing it to run over the ground; the two objects have interacted at the site of the collision, and that is how all causation occurs. For one thing to cause the behaviour of another, it must strike, brush, bump into, tickle or in some other way touch that thing at a shared location. But if the mind resides nowhere or only on its own numinous plane, where can it exert impact on the body? If the soul has no spatial position, how could it make contact with something physical? How do the two ever meet? It would be rather more occult than a concept hitting a billiard ball. Neither Descartes nor any other proponent of substance dualism has come up with a minimally satisfactory solution to this problem, and since one of the most conspicuous features of the relation between mind and body is that the two act upon one another, modern philosophy has written off that position as indefensible.15
But the cognate substance dualism is alive and well in conventional perceptions of society and nature. It is there whenever someone thinks or behaves as though society need not care about what happens in nature, however much the body of nature may bleed – as though it could exist without it. We can easily accept the critique of this version of Cartesian dualism developed by Val Plumwood in her two books Feminism and the Mastery of Nature and Environmental Culture: The Ecological Crisis of Reason: such dualism is there whenever humans put it in their heads that they live in a region levitating somewhere above the biosphere, independent of it, free and able to bracket it off as an inferior order unrelated to theirs, except as a storehouse of resources they can use up in perpetuity.16 Not so much a philosophical programme declared by avid preachers, more a syndrome than a credo, this dualism is present in everything from neoclassical economics to climate change denial and sheer indifference to issues of ecology. Devised for negligence, it has its own causal interaction problem: it has no idea about how society can cause a crisis in nature or vice versa.
To realise that there is an ecological crisis with great potential to affect humans is to break with substance dualism. We are, it turns out, of exactly the same substance as nature, inhabit the same planet and constantly touch each other all over the place. In terms of the philosophy of mind, this is a commitment to substance monism. From here, however, there are two paths to choose between. One can go on to argue that the social and the natural not only share substance, but that they have no significant properties that tell them apart – a substance monism and property monism. This is the position of the hybridists, of Bruno Latour and, as it happens, of Val Plumwood: there is only one substance, and everything made of it has the same essential attributes (we shall soon see what these are). Then there is the view that society is made up of the same substance as nature, but has some highly distinctive properties – what in the philosophy of mind is known as substance monist property dualism.17 To tease out this position, we may first turn to Dale Jacquette’s The Philosophy of Mind: The Metaphysics of Consciousness, a masterpiece in defence of it.
The quandary of mind and body that Descartes struggled with to such unsatisfactory effect has not gone away. My brain is a physical entity. It contains cells, tissue, fluid, neurons, synapses, blood vessels, matter white and black and grey. But do these things also make up my mind? ‘My mind’, Jacquette writes, ‘on casual inspection contains memories, desires, expectations, immediate sensations, embarrassments, likes and dislikes. But my brain on casual inspection contains none of these things.’18 Brain events have weight and colour, but thoughts seem not to. What colour is my thought that Donald Trump is a racist? How much does it weigh? Does it swerve if I turn my car sharply to the right? How could the physicality of that thought as thought be pinpointed and measured? Suppose I attend a concert with Run the Jewels, and suppose the intensity of the performance is heightened by a jury having just acquitted a white policeman for shooting and killing a black man, and suppose a neuroscientist at this moment drops in to subject my brain to observation. She will see neurons firing and flaring like firecrackers, but she cannot possibly inspect or capture my conscious experience as such, the quality of taking in the musical furore or the feeling of shared fury. These subjective states appear nothing at all like the features of a material object. As such, they are not available for third-person observation in the way a microphone or a T-shirt is, nor can they be read off from neuroscientific instruments or described in a strictly physical language.19
At a first introspective