I aim to defend the existence of "borderline cases" of consciousness, cases in which it's neither determinately true nor determinately false that experience is present, but rather things stand somewhere in between.
The main objection against the existence of such cases is that they seem inconceivable: What would it be like to be in such a state, for example? As soon as you try to imagine what it's like, you seem to be imagining some experience or other -- and thus not imagining a genuinely indeterminate case. A couple of weeks ago on this blog, I argued that this apparent inconceivability is the result of an illegitimately paradoxical demand: the demand that we imagine or remember the determinate experiential qualities of something that does not determinately have any experiential qualities.
But defeating that objection against borderline cases of consciousness does not yet, of course, constitute any positive reason to think that borderline cases exist. I now have a new full-length draft paper on that topic here. I'd be interested to hear thoughts and concerns about that paper, if you have the time and interest.
As this week's blog post, I will adapt a piece of that paper that lays out the main positive argument.
[Escher's Day and Night (1938); image source]
To set up the main argument, first consider this quadrilemma concerning animal consciousness:
(1.) Human exceptionalism. Only human beings are determinately conscious.
(2.) Panpsychism. Everything is determinately conscious.
(3.) Saltation. There is a sudden jump between determinately nonconscious and determinately conscious animals, with no indeterminate, in-between cases.
(4.) Indeterminacy. Some animals are neither determinately nonconscious nor determinately conscious, but rather in the indeterminate gray zone between, in much the same way a color might be indeterminately in the zone between blue and green rather than being determinately either color.
For sake of today's post, I'll assume that you reject both panpsychism and human exceptionalism. Thus, the question is between saltation and indeterminacy.
Contra Saltation, Part One: Consciousness Is a Categorical Property with (Probably) a Graded Basis
Consider some standard vague-boundaried properties: baldness, greenness, and extraversion, for example. Each is a categorical property with a graded basis. A person is either determinately bald, determinately non-bald, or in the gray area between. In that sense, baldness is categorical. However, the basis or grounds of baldness is graded: number of hairs and maybe how long, thick, and robust those hairs are. If you have enough hair, you're not bald, but there's no one best place to draw the categorical line. Similarly, greenness and extraversion are categorical properties with graded bases that defy sharp-edged division.
Consider, in contrast, some non-vague properties, such as an electron's being in the ground orbital or not, or a number's being exactly equal to four or not. Being in the ground orbital is a categorical property without a graded basis. That's the "quantum" insight in quantum theory. Bracketing cases of superposition, the electron is either in this orbit, or that one, or that other one, discretely. There's discontinuity as it jumps, rather than gradations of close enough. Similarly, although the real numbers are continuous, a three followed by any finite number of nines is discretely different from exactly four. Being approximately four has a graded basis, but being exactly four is sharp-edged.
Most naturalistic theories of consciousness give consciousness a graded basis. Consider broadcast theories, like Dennett’s "fame in the brain" theory (similarly Tye 2000; Prinz 2012). On such views, a cognitive state is conscious if it is sufficiently "famous" in the brain – that is, if its outputs are sufficiently well-known or available to other cognitive processes, such as working memory, speech production, or long-term planning. Fame, of course, admits of degrees. How much fame is necessary for consciousness? And in what respects, to what systems, for what duration? There’s no theoretical support for positing a sharp, categorical line such that consciousness is determinately absent until there is exactly this much fame in exactly these systems (see Dennett 1998, p. 349; Tye 2000 p. 180-181).
Global Workspace Theories (Baars 1988; Dehaene 2014) similarly treat consciousness as a matter of information sharing and availability across the brain. This also appears to be a matter of degree. Even if typically once a process crosses a certain threshold it tends to quickly become very widely available in a manner suggestive of a phase transition, measured responses and brain activity are sometimes intermediate between standard "conscious" and "nonconscious" patterns. Looking at non-human cases, the graded nature of Global Workspace theories is even clearer. Even entities as neurally decentralized as jellyfish and snails employ neural signals to coordinate whole-body motions. Is that "workspace" enough for consciousness? Artificial systems, also, could presumably be designed with various degrees of centralization and information sharing among their subsystems. Again, there’s no reason to expect a bright line.
Or consider a very different class of theories, which treat animals as conscious if they have the right kinds of general cognitive capacities, such as "universal associative learning", trace conditioning, or ability to match opportunities with needs using a central motion-stabilized body-world interface organized around a sensorimotor ego-center. These too are capacities that come in degrees. How flexible, exactly, must the learning systems be? How long must a memory trace be capable of enduring in a conditioning task, in what modalities, under what conditions? How stable must the body-world interface be and how effective in helping match opportunities with needs? Once again, the categorical property of conscious versus nonconscious rests atop what appears to be a smooth gradation of degrees, varying both within and between species, as well as in evolutionary history and individual development.
Similarly, "higher-order" cognitive processes, self-representation, attention, recurrent feedback networks, even just having something worth calling a "brain" -- all of these candidate grounds of consciousness are either graded properties or are categorical properties (like having a brain) that are in turn grounded in graded properties with borderline cases. Different species have these properties to different degrees, as do different individuals within species, as do different stages of individuals during development. Look from one naturalistic theory to the next -- each grounds consciousness in something graded. Probably some such naturalistic theory is true. Otherwise, we are very much farther from a science of consciousness than even most pessimists are inclined to hope. On such views, an entity is conscious if it has enough of property X, where X depends on which theory is correct, and where "enough" is a vague matter. There are few truly sharp borders in nature.
I see two ways to resist this conclusion, which I will call the Phase Transition View and the Luminous Penny View.
Contra Saltation, Part Two: Against the Phase Transition View
Water cools and cools, not changing much, then suddenly it solidifies into ice. The fatigued wooden beam takes more and more weight, bending just a bit more with each kilogram, then suddenly it snaps and drops its load. On the Phase Transition View, consciousness is like that. The basis of consciousness might admit of degrees, but still there's a sharp and sudden transition between nonconscious and conscious states. When water is at 0.1° C, it's just ordinary liquid water. At 0.0°, something very different happens. When the Global Workspace (say) is size X-1, sure, there's a functional workspace where information is shared among subsystems, there's unified behavior of a sort, but no consciousness. When it hits X -- when there's that one last crucial neural connection, perhaps -- bam! Suddenly everything is different. The bright line has been crossed. There’s a phase transition. The water freezes, the beam snaps, consciousness illuminates the mind.
I'll present a caveat, a dilemma, and a clarification.
The caveat is: Of course the water doesn't instantly become ice. The rod doesn't instantly snap. If you zoom in close enough, there will be intermediate states. The same is likely true for the bases of consciousness on naturalistic views of the sort discussed above, unless those bases rely on genuine quantum-level discontinuities. Someone committed to the impossibility of borderline cases of consciousness even in principle, even for an instant, as a matter of metaphysical necessity, ought to pause here. If the phase transition from nonconscious to conscious needs to be truly instantaneous without a millisecond of in-betweenness, then it cannot align neatly with any ordinary, non-quantum, functional or neurophysiological basis. It will need, somehow, to be sharper-bordered than the natural properties that ground it.
The dilemma is: The Phase Transition View is either empirically unwarranted or it renders consciousness virtually epiphenomenal.
When water becomes ice, not only does it change from liquid to solid, but many of its other properties change. You can cut a block out of it. You can rest a nickel on it. You can bruise your toe when you drop it. When a wooden beam breaks, it emits a loud crack, the load crashes down, and you can now wiggle one end of the beam without wiggling the other. Phase transitions like this are notable because many properties change suddenly and in synchrony. But this does not appear always to happen with consciousness. That precipitates the dilemma.
There are phase transitions in the human brain, of course. One is the transition from sleeping to waking. Much changes quickly when you awaken. You open your eyes and gather more detail from the environment. Your EEG patterns change. You lay down long-term memories better. You start to recall plans from the previous day. However, this phase transition is not the phase transition between nonconscious and conscious, or at least not as a general matter, since you often have experiences in your sleep. Although people sometimes say they are "unconscious" when they are dreaming, that's not the sense of consciousness at issue here, since dreaming is an experiential state. There's something it’s like to dream. Perhaps there is a phase transition between REM sleep, associated with longer, narratively complex dreams, and nREM sleep. But that probably isn't the division between conscious and nonconscious either, since people often also report dream experiences during nREM sleep. Similarly, the difference between being under general anesthesia and being in an ordinary waking state doesn't appear to map neatly onto a sharp conscious/nonconscious distinction, since people can apparently sometimes be conscious under general anesthesia and there appear to be a variety of intermediate states and dissociable networks that don't change instantly and in synchrony, even if there are also often rapid phase transitions.
While one could speculate that all of the subphases and substates of sleep and anesthesia divide sharply into determinately conscious and determinately nonconscious, the empirical evidence does not provide positive support for such a view. The Phase Transition View, to the extent it models itself on water freezing and beams breaking, is thus empirically unsupported in the human case. Sometimes there are sudden phase transitions in the brain. However, the balance of evidence does not suggest that falling asleep or waking, starting to dream or ceasing to dream, falling into anesthesia or rising out of it, is always a sharp transition between conscious and nonconscious, where a wide range of cognitive and neurophysiological properties change suddenly and in synchrony. The Phase Transition View, if intended as a defense of saltation, is committed to a negative existential generalization: There can be no borderline cases of consciousness. This is a very strong claim, which fits at best uneasily with the empirical data.
Let me emphasize that last point, by way of clarification. The Phase Transition View, as articulated here with respect to the question of whether borderline consciousness is possible at all, that is, whether borderline consciousness ever exists, is much bolder than any empirical claim that transitions from nonconscious to conscious states are typically phase-like. The argument here in no way conflicts with empirical claims by, for example, Lee et al. (2011) and Dehaene (2014) that phase transitions are typical and important in a person or cognitive process transitioning from nonconscious to conscious.
The Phase Transition View looks empirically even weaker when we consider human development and non-human animals. It could have been the case that when we look across the animal kingdom we see something like a "phase transition" between animals with and without consciousness. These animals over here have the markers of consciousness and a wide range of corresponding capacities, and those animals over there do not, with no animals in the middle. Instead, nonhuman animals have approximately a continuum of capacities. Similarly, in human development we could have seen evidence for a moment when the lights turn on, so to speak, in the fetus or the infant, consciousness arrives, and suddenly everything is visibly different. But there is no evidence of such a saltation.
That's the first horn of the dilemma for the Phase Transition View: Accept that the sharp transition between nonconscious and conscious should be accompanied by the dramatic and sudden change of many other properties, then face the empirical evidence that the conscious/nonconscious border does not always involve a sharp, synchronous, wide-ranging transition. The Phase Transition View can escape by retreating to the second horn of the dilemma, according to which consciousness is cognitively, behaviorally, and neurophysiologically unimportant. On second-horn Phase Transition thinking, although consciousness always transitions sharply and dramatically, nothing else need change much. The lights turn on, but the brain need hardly change at all. The lights turn on, but there need be no correspondingly dramatic change in memory, or attention, or self-knowledge, or action planning, or sensory integration, or.... All of the latter still change slowly or asynchronously, in accord with the empirical evidence.
This view is unattractive for at least three reasons. First, it dissociates consciousness from its naturalistic bases. We began by thinking that consciousness is information sharing or self-representation or whatever, but now we are committed to saying that consciousness can change radically in a near-instant, while information sharing or self-representation or whatever hardly changes at all. Second, it dissociates consciousness from the evidence for consciousness. The evidence for consciousness is, presumably, performance on introspective or other cognitive tasks, or neurophysiological conditions associated with introspective reports and cognitive performance; but now we are postulating big changes in consciousness that elude such methods. Third, most readers, I assume, think that consciousness is important, not just intrinsically but also for its effects on what you do and how you think. But now consciousness seems not to matter so much.
The Phase Transition View postulates a sharp border, like the change from liquid to solid, where consciousness always changes suddenly, with no borderline cases. It's this big change that precipitates the dilemma, since either the Phase Transition advocate should also expect there always also to be sudden, synchronous cognitive and neurophysiological changes (in conflict with the most natural reading of the empirical evidence) or they should not expect such changes (making consciousness approximately epiphenomenal).
The saltationist can attempt to escape these objections by jettisoning the idea that the sharp border involves a big change in consciousness. It might instead involve the discrete appearance of a tiny smidgen of consciousness. This is the Luminous Penny View.
Contra Saltation, Part Three: Against the Luminous Penny View
Being conscious might be like having money. You might have a little money, or you might have a lot of money, but having any money at all is discretely different from having not a single cent. [Borderline cases of money are probably possible, but disregard that for sake of the example.] Maybe a sea anemone has just a tiny bit of consciousness, a wee flicker of experience -- at one moment a barely felt impulse to withdraw from something noxious, at another a general sensation of the current sweeping from right to left. Maybe that’s $1.50 of consciousness. You, in contrast, might be a consciousness millionaire, with richly detailed consciousness in several modalities at once. However, both you and the anemone, on this view, are discretely different from an electron or a stone, entirely devoid of consciousness. Charles Siewert imagines the visual field slowly collapsing. It shrinks and shrinks until nothing remains but a tiny gray dot in the center. Finally, the dot winks out. In this way, there might be a quantitative difference between lots of visual consciousness and a minimum of it, and then a discontinuous qualitative difference between the minimum possible visual experience and none at all.
On the Luminous Penny View, there is a saltation from nonconscious to conscious in the sense that there are no in-between states in which consciousness is neither determinately present nor determinately absent. Yet the saltation is to such an impoverished state of consciousness that it is almost empirically indistinguishable from lacking consciousness. Analogously, in purchasing power, having a single penny is almost empirically indistinguishable from complete bankruptcy. Still, that pennysworth of consciousness is the difference between the "lights being on", so to speak, and the lights being off. It is a luminous penny.
The view escapes the empirical concerns that face the Phase Transition View, since we ought no longer expect big empirical consequences from the sudden transition from nonconscious to conscious. However, the Luminous Penny View faces a challenge in locating the lower bound of consciousness, both for states and for animals.
Start with animals. What kind of animal would have only a pennysworth of consciousness? A lizard, maybe? That seems an odd view. Lizards have fairly complex visual capacities. If they are visually conscious at all, it seems natural to suppose that their visual consciousness would approximately match their visual capacities -- or at least that there would be some visual complexity, more than the minimum possible, more than Siewert's tiny gray dot. It's equally odd to suppose that a lizard would be conscious without having visual consciousness. What would its experience be? A bare minimal striving, even simpler than the states imaginatively attributed the anemone a few paragraphs back? A mere thought of "here, now"?
More natural is to suppose that if a lizard is determinately conscious, it has more than the most minimal speck of consciousness. To find the minimal case, we must then look toward simpler organisms. How about ants? Snails? The argument repeats: These entities have more than minimal sensory capacities, so if they are conscious it’s reasonable to suppose that they have sensory experience with some detail, more than a pennysworth. Reasoning of this sort leads David Chalmers to a panpsychist conclusion: The simplest possible consciousness requires the simplest possible sensory system, such as the simple too-cold/okay of a thermostat.
The Luminous Penny View thus faces its own dilemma: Either slide far down the scale of complexity to a position nearly panpsychist or postulate the existence of some middle-complexity organism that possesses a single dot of minimal consciousness despite having a wealth of sensory sensitivity.
Perhaps the problem is in the initial move of quantifying consciousness, that is, in the commitment to saying that complex experiences somehow involve "more" consciousness than simple experiences? Maybe! But if you drop that assumption, you drop the luminous penny solution to the problem of saltation.
State transitions in adult humans raise a related worry. We have plausibly nonconscious states on one side (perhaps dreamless sleep), indisputably conscious states on the other side (normal waking states), and complex transitional states between them that lack the kind of simple structure one might expect to produce exactly a determinate pennysworth of consciousness and no more.
If consciousness requires sophisticated self-representational capacity (as, for example, on "higher order" views), lizard or garden snail consciousness is presumably out of the question. But what kind of animal, in what kind of state, would have exactly one self-representation of maximally simple content? (Only always "I exist" and nothing more?) Self-representational views fit much better with either phase transition views (if phase transition views could be empirically supported) or with gradualist views that allow for periods of indeterminacy as self-representational capacities slowly take shape and, to quote Wittgenstein, "light dawns gradually over the whole" (Wittgenstein 1951/1969, §141).
If you’re looking for a penny, ask a panpsychist (or a near cousin of a panpsychist, such as an Integrated Information Theorist). Maximally simple systems are the appropriate hunting grounds for maximally simple consciousness, if such a thing as maximally simple consciousness exists at all. From something as large, complicated, and fuzzy-bordered as brain processes, we ought to expect either large, sudden phase transitions or the gradual fade-in of something much richer than a penny.
Full manuscript:
Borderline Consciousness, When It's Neither Determinately True nor Determinately False That Consciousness Is Present.
