COLIN ALLEN

THE DISCOVERY OF ANIMAL CONSCIOUSNESS: ANOPTIMISTIC ASSESSMENT

What can we know about the conscious mental states of (nonhuman)animals? Faced with statutory requirements to assess animal welfare, thisquestion has taken on practical importance for researchers and agricultur-ists (Bekoff 1994, 1998). But the question cannot be answered without firstsaying something about the sense in which “consciousness” is being used.

The term “consciousness” is ambiguous in English (Wilkes 1984, 1995;Nelkin 1993). It is applied to the distinction between being asleep andawake, to the distinction between responsiveness and unresponsiveness toenvironmental features, to the distinction between deliberate and reflexivebehaviors, to the fact that some neurological events “feel like something”to their subjects while others have no associated phenomenology, and tothe distinction between self-awareness and the lack of self-awareness.

The application of the term “conscious” in the first two senses – beingawake, or being responsive to certain stimuli – is uncontroversial whenapplied to animals. The third and fourth senses are controversial. It has beendisputed that animals have the capacity for reasoned, deliberate action (seeCarruthers 1992), and that their experiences provide them with a qualita-tive feel, or phenomenology (Carruthers 1992, 1996; Bermond 1997, thisconference). The fifth sense – self-awareness – is also controversial in thescientific literature, where there is an active debate about the significanceof mirror self-recognition as a sign of conscious self-awareness.

In this paper I shall focus primarily on the fourth sense for it is thephenomenology of pain that most people regard as the most significantevil arising from certain research, industrial, and agricultural practices.This identification of the sense in which “consciousness” is intended fallsfar short of a complete definition of the term, but that is to be expectedbecause such a definition is more likely to be the endpoint of scientificinvestigation rather than a starting point (Allen & Bekoff 1997). Althoughthis sense of consciousness is perhaps the most difficult to pin down, itwould be prematurely defeatist to take the position of Beer (1992, p. 79),who has suggested that if ethologists would restrict their claims for animalawareness to sensation and perception then “even tough-minded criticswould be more receptive”. Progress on the more controversial questionswill ultimately be more exciting than rapprochement with the critics.

Journal of Agricultural and Environmental Ethics10: 217–225, 1998.c 1998Kluwer Academic Publishers. Printed in the Netherlands.

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To frame the discussion, let us consider two questions have been tradi-tionally asked about nonhuman consciousness:

The Distribution Question:Which nonhuman animals are conscious?The Phenomenological Question:What is it like to be a (species X)?

At bottom, both the distribution and phenomenological questions areepistemologicalquestions. They concern how weknowthat nonhumans areconsciousness and how weknowwhat their experiences are like. Philoso-phers of mind, who are typically not concerned with questions specificallyabout animal consciousness,have also pursued ontological questions aboutwhat consciousness is. In this literature there are numerous distinctions, forexample Rosenthal’s (1986) distinction between state consciousness (i.e.,that a particular experience is a conscious experience) and creature con-sciousness (i.e. that a particular organism is conscious). These distinctionspartly correspond to and partly cross-cut the 5-part distinction betweensenses of consciousness given above.

Although such distinctions can be useful, from the perspective of aphilosopher of science, one might reasonably deny that it is a philosopher’sjob to provide a theory of what consciousness is. Also, Marc Bekoff and Ihave argued (Allen & Bekoff 1997) that scientists interested in questionsabout animal consciousness might do better if they were to attempt tounderstand the epistemological questions before the ontological questions,for it is the epistemological questions that are particularly acute when thesubjects are nonhuman animals.

THE DISTRIBUTION QUESTION

I shall assume, without argument, that humans possess conscious states inthe phenomenological sense. The distribution question is about the distri-bution of consciousness among nonhuman animals. Two extreme viewsmay be identified. One view, that I shall labelUniversal Anthropomor-phismassumes that animals are simply scaly, feathered, or furry, larger orsmaller versions of people. Thus understood, universal anthropomorphisminvolves the attribution of conscious states to all nonhuman animals. Theother view,Strict Chauvinism, regards all nonhuman animals as complexautomata, devoid of conscious experience, operating in the mode of a“zombie”. Strict chauvinism thus provides the most restricted answer tothe distribution question.

Strict chauvinism has itslocus classicusin the work of Rene Descartes.Descartes was convinced of the following two facts: that the behavior of

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nonhuman animals could be explained by the mechanical principles oper-ating in the nervous system, and that the ability of normal adult humans toact according to reasons and to carry on a normal conversation could notbe explained mechanically. He concluded that the explanation of humanaction and speech lay in the operations of conscious mind, a substancewhose existence, separate from physical matter, he had previously demon-strated to his own satisfaction (if not to everyone’s). By focusing on lan-guage and reason as revealed in action, Descartes provided behavioralcriteria for the attribution of consciousness to other humans (who mostlysatisfy the criteria) and to the members of other species (who failed them)(Radner & Radner 1996). In western philosophy, the discussion of reasonin animals can be traced back to the ancient Greeks (Sorabji 1993), withAristotle denying that animals reason.

Nowadays, few philosophers consider immaterial substance to be aviable substrate for conscious mind. Most are convinced by scientificresults indicating that the brain is the material basis for all mental phe-nomena, including consciousness. Much of what goes on in the brain is, ofcourse, not accessible to consciousness and while we have some generalideas, it is far from clear exactly which features of the brain are responsiblefor consciousness. Hence there is no simple inference that can be drawnfrom “has a working brain” to “is conscious” and this is where worriesabout the distribution of consciousness – who or what is conscious? –can get their purchase. To put it briefly – differences in nervous systemstructure or function can be used to generate skeptical worries about theexistence of consciousness in animals with brains that differ from our own.

Such worries seem entirely reasonable when applied to animals withnervous system of orders of magnitude less size than our own. AlthoughGriffin (1984) has argued to the contrary, that consciousness might be evenmore important for creatures with simple nervous systems, his suggestionseems to run contrary to the mounting neuropsychological evidence corre-lating conscious experience to the activity of more complex structures inthe brain.

Neither extreme position seems defensible. The truth probably liessomewhere in the boring middle – some animals have qualitative experi-ences, and some don’t. Because not all conscious experiences are alike, itseems possible that members of other species may have experiences thatare not at all like those of humans. What might they be like? This is thephenomenological question.

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THE PHENOMENOLOGICAL QUESTION

Like the distribution question, philosophical interest in the phenomenolog-ical question can also be traced to Descartes (Carruthers 1992). The con-temporary discussion has, however, largely been shaped by Nagel (1974)in his seminal paper “What is it like to be a bat?” In this paper, Nagelasserts that there is something that it is like to be a conscious subject – i.e.,that conscious experiences have a “qualitative aspect” or “phenomenolog-ical feel” for the subjects of those experiences – but that in the case ofdifferent species we have no way of knowing what those experiences arelike. Nagel assumes that bats do have conscious experiences and seeks toquestion the possibility of scientific knowledge of the character of thoseexperiences. Thus, he sets aside the distribution question and focuses onthe phenomenological question: What is it like to be the member of anotherspecies?

Nagel’s view is that science, which aims for objective descriptionsof natural phenomena, cannot provide an adequate account of consciousexperience, which is essentially subjective. At the Wageningen confer-ence, some of the discussants took this to show thatall questions aboutconsciousness are outside the domain of objective science, but I think thatNagel’s argument is not strong enough to force this conclusion.

The argument rests on a premise that subjective phenomena cannot beexplained objectively. This premise has an air of plausibility for how cansomething that is of one type be described in terms that are of another type?But, first, I think the argument can be reversed, for if science is essentiallyobjective while human consciousness is essentially subjective it mightbe argued that subjective human consciousness is thereby incapable ofadequately comprehending science. But this conclusion is absurd. If onenonetheless accepts the view that subjectively described phenomena arebeyond the reach of objective understanding, one should be required toexplain the asymmetry that allows objectively described phenomena to bewithin the reach of subjective understanding.

Second, even if you do not find this response to be convincing, itdoes not matter for my purpose in this paper, which is to investigate thedistribution question more thoroughly. I take the existence of consciousexperiences in you, the reader, to be an objective fact about the worldthat can be known from many points of view. I do not see any reasonfor thinking differently about members of other species. Thus, even if thephenomenological question is beyond the reach of science (and it may notbe – see Akins 1995), the distribution question need not be.

Nagel-inspired concerns about the phenomenological question havebeen misunderstood and they have tended to lead researchers away from

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areas where more substantial progress is needed, and, I believe, possi-ble. Nagel’s pessimistic answer can be replaced with the more optimisticstrategy of Allen & Bekoff (1997) to a variant of the distribution question:

The Phenomenological Distribution Question:Is there something it is like to be a ?

This question, like Nagel’s is intended to focus attention to members ofdifferent species on a case by case basis.

THE OPTIMISTIC STRATEGY

The argument of Allen & Bekoff for the conclusion that progress is possibleon the distribution question, even if the phenomenological question ismuch less tractable, is really quite simple. Imagine that one lacks a certainneurotransmitter known to be necessary for the action of a psychoactivedrug. One can know that other people have conscious experiences whenthey take this drug even if one is utterly unable to imagine, and henceunable to know, what it is like to have those experiences. Now, one’sconfidence in the conclusion that other people have conscious experiencesunder the influence of this drug is, of course, bolstered by the possibility ofdiscussing it with them. If the same kind of confidence in the consciousnessof animal experiences is to be had, we must have an alternative to verbalinterrogation.

Before discussing what such an alternative might be, it is worth beinga little more circumspect about the philosophical methodology here. Thepurpose is not to give a fixed definition of consciousness. Rather, the aim isto identify phenomena which might plausibly be investigated empiricallyas instances of consciousness. One basic strategy for identifying the rele-vant phenomena is to employ some kind of argument from analogy. Thegeneral form of this is to correlate consciousness in humans with some kindof property, P, and to argue that by analogy we can attribute consciousnessto those animals that also possess P.

The trouble with this basic strategy is that it is extremely weak as longas the relationship between P (whether behavioral or neurophysiological)and consciousness is no more articulated than “correlation in the humancase”. There are two reasons for this. The first, and less interesting reasonto my mind, is that for every P one can find another property Q that thehuman possesses and the animal lacks, and one can then use the absenceof Q to reject the analogy.

The second reason is more interesting though, for it goes to the heart ofthe current debate about consciousness. This is that seemingly no amount

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of behavioral information can logically guarantee any facts about con-sciousness, even in other humans. This claim is sometimes illustrated bythe invention of the philosophers’ “zombie” (see Searle 1992) – not tobe confused with the much more easily recognized Hollywood creatureof the same name. The glazed eyes, expressionless faces and stiff move-ments of the Hollywood zombies are, pardon the pun, dead giveaways.But philosophers’ zombies (“phi-zombies” for short) are, by hypothesis,utterly indistinguishable from their human counterparts. Ask a phi-zombieto compare the taste of Grolsch with Heineken, and the more sophisticatedones will know exactly the right thing to say. If phi-zombies are possi-ble (many think they are not) then no amount of behavioral evidence canassure our attributions of consciousness. Thus, no matter how perfect thecorrelation between P and consciousness in humans, there is no guaranteethat it will be associated with consciousness in other organisms.

A number of philosophers have raised questions about the coherence ofthe concept of phi-zombies but this is not the place to get into a discussionof that. Rather, the point I wish to note is that it is not sufficient to relyon the weak correlation of some property P to consciousness in the humancase, in order to make the argument that P is an indicator of consciousnessin the animal case. Attempts to demonstrate “language” or “reasoning” inanimals are, for this reason, doomed to endless controversy. Instead, it isnecessary to justify a tighter connection between the preferred property Pand consciousness.

Some philosophers have attempted to do this for language by making itessential to the contents of conscious thoughts (Carruthers 1996). I will notexamine those arguments here, for they deserve more space and time, butI think it is fair to say that such arguments have a considerable burden ofproof given that many of us think that some (more or less) of our consciousstates seem not to involve language in any significant way (Allen 1998).

The preferred approach of Allen & Bekoff (1997) is to start by bringingconsiderations of evolutionary biology to bear on the question of whatconsciousness is for. Perhaps consciousness is epiphenomenal – devoidof any effect beyond the subjectivity of the experiences – and thereforedevoid of biological functionality. But, as a working hypothesis, I favor astance which attributes biological functions to conscious experience.

A very simplistic (and, I believe, incorrect) view about the function ofconsciousness is that it notifies an organism of sensory input and promptsa response. Given this simplistic view, epiphenomenalism immediatelythreatens, for it seems expedient to cut out the middleman and go directlyfrom stimulus to response. It would clearly be gratuitous to attribute con-sciousness any time an organism responded to a stimulus. An example

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which illustrates this point well involves decapitated alligators, whoseforelimbs will swipe quite precisely at the point of a scalpel incision inthe headless torso (Kleister, pers. comm.) by means of a spinal reflex. Onthe reasonable assumption that a headless organism feels no pain, it can beseen that attributing a conscious experience of pain would add nothing tothe explanation of the organism’s behavior.

A slightly more sophisticated is the view that conscious inputs allowa central decision-making module to assess the various inputs and choosean appropriate response. One trouble with this view is it does not reallyhelp us to understand why the same job could not be done completelyunconsciously by a multiplexer that computed responses according to thecombinations of its inputs. Another trouble is that it raises the specter ofa homunculus doing all the comparisons, and hence the fear of an infiniteregress (Dennett 1991). Here is, however, the germ of a another idea aboutconscious experience.

To explain this idea, it will be helpful to take a detour through the func-tions of sensory systems. Animals possess sensory organs whose functionit is to transduce environmental energy to nervous signals. Imagine youare a simple organism capable of following a chemical gradient until youreaches some goal item, such as a piece of food or a mate. In the realworld, you will not always find what you need. For instance, sometimesthe environmental cue will have provided misleading information – per-haps there never was food or a mate at the signal-producing end. Othertimes, the information will have been accurate but someone else may havebeaten you to the desired object. Now, if you do not have the means todiscriminate these alternatives, then you are faced with a difficulty. For ifyou are faced with a false signal, you would be better off to respond lessvigorously. Whereas, if faced with a correct signal but lots of competitionfor the resource, you would be better off to respond more vigorously. Thusit is likely that, under certain conditions, there will be a selective advan-tage to organisms who can modulate their responses to certain sensorystimulations in connection with information about the reliability of thosestimulations as indicators of useful external conditions.

Now, some organisms, notably humans, are capable of responding tothe apparent content of their sensory perceptions while simultaneouslyacting in ways that disavow the appearances. Visual illusions provide arich vein of examples, where it is common to report that an image looksa particular way (one line longer than another, for instance) and to reportthat “really” it is not. In other words, humans are capable of reportingthat their sensory perceptions are in error. I maintain that what makesthis compelling as evidence of consciousness is not the use of language,

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but that it seems to require an operative distinction, within the organism,between the way things appear to it and the way it takes things to be. Someorganisms are bound by their sensory perceptions to act in ways that accordwith those perceptions. To attribute consciousness in these cases, or evento talk of appearances, is explanatorily vacuous as it would be to attributeconsciousness to the decapitated alligator that it is being pierced with asharp object. Where the organism’s behavior requires us to postulate thatit maintains separate representations of appearance and reality, then thereis a much stronger theoretical reason for identifying some of its internalstates as appearance states, and insofar as we can obtain evidence that theorganism has epistemic access to the contents of its own appearance states,there is a theoretical reason for treating these states as phenomenological.

One common definition of conscious states is that they are appearancestates, but this would be too superficial an identification the present con-text. We are not, however, necessarily after adefinitionof consciousness,or what it is to be conscious. Rather, we are in the position of seekingclues – plausible places to start looking for further evidence. It is in thisspirit that the capacity for detection of perceptual error is offered as a clueto attributions of consciousness in nonhuman animals. For example, anorganism that is presented with a device that systematically produces illu-sions (such as an image distorted by a spherical mirror) might be trainedto use both the real and apparent size of reflected objects to respond todifferent cues to demonstrate that it simultaneously represents its visualappearance independently from the judged reality.

It is possible to investigate the capacity for error detection in the absenceof language, but the design of convincing experiments will take consider-able ingenuity. Philosophers have shown considerable ingenuity at design-ing thought experiments to test ontological theories of consciousness. Ifsimilar amounts of effort were expended on the equal or greater challengeof designing real experiments, one could be quite optimistic about theprospects for an improved understanding of consciousness in nonhumananimals.

ACKNOWLEDGEMENTS

My thanks go to the organisers of the Wageningen conference, andespecially to Ruud van den Bos and Soemini Kasanmoentalib for theirhospitality. I am grateful to Peter Carruthers for discussing these issues.Finally, many of the ideas expressed in this paper are the joint product ofa friendship and collaboration with Marc Bekoff.

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Department of PhilosophyTexas A&M UniversityCollege Station, TX 77843–4237<colin–allen@tamu.edu>