The Sucker, The Sucker!
By Amia Srinivasan, The London Book Review
What does it feel like to be an octopus? Does it feel like anything at all? Or are octopuses, as Godfrey-Smith puts it, ‘just biochemical machines for which all is dark inside’? This form of question – ‘what is it like to be a bat?’ Thomas Nagel asked in a hugely influential paper in 1974 – is philosophical shorthand for asking whether a creature is conscious. Many philosophers think consciousness is an all or nothing phenomenon: you either have it or you don’t. Humans have it, as do perhaps chimps and dolphins. Mice, ants and amoebas presumably do not. Part of the motivation for the all or nothing view is that it is difficult to imagine consciousness being possessed in degrees. Other cognitive attributes – like memory, linguistic capacity and problem-solving ability – are the sorts of thing that can and do vary in degree from creature to creature, and species to species. But it is harder to see how consciousness can vary in that way. As Godfrey-Smith puts it, ‘how can an animal be halfway to having it feel like something to be that animal?’ Yet, if consciousness is a natural thing, something that evolved over time, it seems unlikely that it just popped up at some point in evolutionary history, fully formed.
Godfrey-Smith starts with the conviction that consciousness is an evolved thing, and accepts the conclusion that it has more primitive precursors: that it comes in degrees after all. Consciousness – the possession of an ‘inner’ model of the ‘outer’ world, or the sense of having an integrated, subjective perspective on the world – is, on his view, just a highly evolved form of what he calls ‘subjective experience’. Many animals, Godfrey-Smith thinks, have some degree of subjective experience, even if it falls short of full-blown consciousness. He points to what the physiologist Derek Denton called the ‘primordial emotions’: thirst, lack of air, physical pain. These sensations intrude on our more complex mental processes, refusing to be dismissed. They hark back to a more rudimentary form of experiencing the world – a form, Godfrey-Smith thinks, that does not require a sophisticated inner model of the world. ‘Do you think,’ he asks, that pain, thirst or shortness of breath ‘only feel like something because of sophisticated cognitive processing in mammals that has arisen late in evolution? I doubt it.’
Godfrey-Smith suggests that the octopus is, phenomenologically speaking, in a hybrid situation: its arms are partly self, and partly other. Because of this, the octopus is sometimes held up as a mascot for the ‘embodied cognition’ movement in psychology, according to which the physical body, by constraining and making possible certain actions, is itself ‘intelligent’. The human ability to walk, for example, is not simply a matter of top-down brain control, but also a function of the angles of our joints; in this sense, our bodies encode information vital for intelligent action. There can be little doubt that an octopus’s embodiment is radically different from our own, and that understanding an octopus’s mind requires us to grasp its particular form of embodiment. But thinking about the octopus in terms of embodied cognition may undersell its strangeness. While it makes sense to think of our own bodies in terms of the constraints and opportunities they afford, the octopus’s body, as Godfrey-Smith says, is ‘protean, all possibility’. Even asking how much the body contributes to intelligent action presupposes a division between brain and body that seems not to apply to the octopus. The octopus’s body is pervaded by nervousness: it is not a thing controlled by the animal’s thinking part, but itself a thinking thing.
A further oddity in thinking about octopus experience has to do with the creature’s relationship to colour. An octopus’s skin is a layered screen of pixel-like sacs of colour called chromatophores, which make it possible for an octopus to change its colour at will to match its surroundings or threaten an aggressor. The so-called mimic octopus can impersonate more than 15 different animals, including flounder, lionfish and sea snakes, by changing its colour and shape. An octopus’s colour also seems to indicate its mood – some octopuses turn white after being caressed for a long time by humans, as well as after mating. The chromatic displays produced by octopuses can include elaborate patterns of stripes and spots, flashing rings and waves of rippling colour. Yet octopuses – like most cephalopods – appear to be colour-blind. Their eyes lack the variety of photoreceptors required to see colour, and octopuses are unable to distinguish between differently coloured objects in experimental tests. Researchers have recently discovered that octopuses have photoreceptors not only in their eyes but also in their skin, which suggests that the skin can see (as well as taste and smell), either by sending the visual information it receives to the octopus’s brain, or by processing the information itself. Both options are weird: either the skin as a whole becomes an eye, or the octopus’s body sees independently of the octopus’s brain. Even this isn’t the whole story, since the photoreceptors found in an octopus’s skin are, like those in its eyes, insufficient to detect colour. The best working hypothesis is that some complex interaction between the skin’s photoreceptors and chromatophores allows the octopus to adopt colours it cannot see.