What Animals Can Suffer?
Sentience, Consciousness, and Suffering

Matt Ball

See also: Fish, Consciousness, and Advocacy

What animals are capable of conscious suffering?

For the most part, I don't think that many people pursue this question in good faith. They usually start with their desired conclusion, define their terms accordingly, and selectively present evidence to make their conclusion true. (One irony of this is that the anti-veggies argue the same point as the religious vegans; the latter to keep their dogma simple, the former to show how impossible -- and thus absurd -- veganism is.)

Often, the question that is asked is not the ethically relevant one – that of conscious suffering (see Beyond and Theory for philosophical discussion). Being able to sense and react, having a nervous system, and even having mechanisms related to pain are not the same as being able to consciously have a subjective experience of suffering.

This essay will try to look at the common ways of judging organisms worthy of ethical concern, and why, given the current understanding of neurology, these are not appropriate measures. If vegan advocates dogmatically insist that all non-plant organisms suffer, or randomly defends some animals, the compelling ethical case for veganism is undermined. [For a discussion of the ethical relevance of suffering, see "A Theory of Ethics."]

Facts vs. Questions

There are a number of factual issues that need to be addressed in determining which animals can suffer. However, I can't imagine there is any true certainty at any point in the line of reasoning. After factual questions, there are ethical questions, followed by strategic questions.

One example of a chain of questions and ethical implications can be built around the questions of insect suffering:

1a. Does a certain level / amount of neurology / chemistry indicate consciousness -- i.e., the ability to have subjective experiences (see below) such as suffering.

1b. If, for instance, insects are capable of suffering, is their suffering of a similar nature (and magnitude) as that of higher vertebrates? Or is it quantitatively and/or qualitatively different?

2. Once these questions are answered (assuming they could be), how do you weight this suffering compared to the rest of suffering in the world? For example, if insects are suffering but in a quantitatively and qualitatively dissimilar fashion to higher vertebrates, how do you integrate this into one's set of ethics?

3. If you are a deontologist who believes each animal -- including insects -- has an absolute right to life, then we are all mass murderers on the order of Stalin and Hitler (just from the slaughter of insects during crop harvest alone), and the only ethical course of action may be to commit suicide. If one is a utilitarian concerned with decreasing suffering, then one would perhaps no longer work to promote veganism (if the insects are actually suffering as they die), but rather to decrease human population. (One would also, almost certainly, avoid cultivated crops as much as possible, probably taking up hunting.)

I think there is so much uncertainty in question #1a that there might not be much point to discussions of any other question. But there is enough understanding currently available to be able to come to a better understanding of the nature of the question.

Sensing vs. Feeling

Given our human ability to experience conscious emotion, we are inclined to assign “mind” to others. Our empathetic judgment of actions as emotion creates significant problems with looking to behavioral clues for the actual existence of subjective experience.

As pointed out by neurologist Antonio Damasio, in The Feeling of What Happens:

In fact, you can find the basic configurations of emotions in simple organisms, even in unicellular organisms, and you will find yourself attributing emotions such as happiness or fear or anger to very simple creatures, who, in all likelihood, have no feeling of such emotions in the sense that you or I do, creatures which are too simple to have a brain, or, having one, too rudimentary to have a mind. You make those attributions purely on the basis of the movements of the organism, the speed of each act, the number of acts per unit of time, the style of the movements, and so on. You can do the same thing with a simple chip moving about on a computer screen. Some jagged fast movements will appear "angry," harmonious but explosive jumps will look "joyous," recoiling motions will look "fearful." A video that depicts several geometric shapes moving about at different rates and holding varied relationships reliably elicits attributions of emotions state from normal adults and even children.

Sentience -- strictly speaking, the ability to sense -- exists at nearly every level of biological life, including single-celled creatures. Can sensing and reacting be ethically relevant? A sunflower can sense and react to the sun, but is there any anything ethically relevant involved in cutting a sunflower to bring it inside? Does ethical relevance appear with the presence of "nerves," as opposed to a plant's sensory cells? Does a clam have ethically relevant experiences? A sponge? A sea anemone (see Appendix C)? Damasio gives this example:

Somewhere between [a computer] chip and your pet sits one of the living creatures that has most contributed to progress in neurobiology, a marine snail known as Aplysia californica. Eric Kandel and his colleagues have made great inroads in the study of memory using this very simple snail which may not have much of a mind but certainly has a scientifically decipherable nervous system and many interesting behaviors. Well, Aplysia may not have feelings as you or I do, but it has something not unlike emotions. Touch the gill of an Aplysia, and you will see the gill recoil swiftly and completely, while the heart rate of Aplysia goes up and it releases ink into the surroundings to confuse the enemy, a bit like James Bond when he is hotly pursued by Dr. No. Aplysia is emoting with a miniconcert of responses that is formally no different, only simpler, from the one that you or I could display under comparable circumstances. To the degree that Aplysia can represent its emotive state in the nervous system, it may have the makings of a feeling. We do not know whether Aplysia has feelings or not, but it is extremely difficult to imagine that Aplysia would know of such feelings if it does have them.

Beyond clearly unconscious patterns on a screen are the questions surrounding machines that actually can sense, react, learn, avoid, heal. We are capable of creating vastly complex and "sentient" creatures. There is nothing to indicate that these won't become more complex and capable as time goes on. Yet is there any indication that they are or will soon become capable of subjective experience, a conscious awareness of their feelings?

Some might answer that, "Of course machines can't experience feelings." But is there any reason to believe that there is something inherent in the simplest neurochemicals (as opposed to the organization / network of neural circuitry itself) that precludes consciousness arising from any other mechanism?

For all these reasons, I think conscious awareness can't be associated simply with the ability to sense or react, the presence of neurons, or certain behaviors. As Damasio documents in Feeling, humans are capable of performing many complex actions / computations without having a subjective experience of them.

Feeling vs. Feeling a Feeling

Perhaps the most important fact to keep in mind is that sensing (feeling) is not the same as consciously, subjectively experiencing a feeling. As Damasio writes:

Some readers may be puzzled by the distinction between "feeling" and "knowing that we have a feeling." Doesn't the state of feeling imply, of necessity, that the feeler organism is fully conscious of the emotion and feeling that are unfolding? I am suggesting that it does not, that an organism may represent in neural and mental patterns the state that we conscious creatures call a feeling, without ever knowing that the feeling is taking place. This separation is difficult to envision, not only because the traditional meanings of the words block our view, but because we tend to be conscious of our feelings. There is, however, no evidence that we are conscious of all our feelings, and much to suggest that we are not. [See further discussion in the Appendix B.]

This distinction is a very difficult concept for a self-aware person to fathom. However, one cannot make coherent ethical decisions without at least some level of understanding.

Pain vs. Suffering

What about the presence in other animals of biological mechanisms utilized in humans for sensing and dealing with pain; e.g., opiates? Rather than thinking that opiates serve the same purpose in bees or other creatures that they do in humans, the widespread presence of these chemicals may simply be a testament to the conservativism of evolution. Many chemicals have proved to be highly useful many millions of years ago, and evolution has found a way to continue to utilize them in future organisms If you look at autonomous nervous reactions to stimuli (such as "pain" reactions mediated by the spinal cord), the same neurochemicals are quite possibly used in Aplysia and sea anemones. (See any book by Richard Dawkins for a discussion of evolution’s conservatism).

Regardless, the neural mechanisms of pain do not create a conscious, subjective experience of suffering. Damasio:

Pain does not qualify for emotion, either. Pain is the consequence of a state of local dysfunction in a living tissue, the consequence of a stimulus -- impending or actual tissue damage -- which causes the sensation of pain but also causes regulatory responses such as reflexes and may also induce emotions on its own. In other words, emotions can be caused by the same stimulus that causes pain, but they are a different result from the same cause. Subsequently, we can come to know that we have pain and that we are having an emotion associated with it, provided there is consciousness.

[After a description of the neural mechanisms of sensing pain.]

Would one or all of those neural patters of injured tissue be the same thing as knowing one had pain? And the answer is, not really. Knowing that you have pain requires something else that occurs after the neural patterns that correspond to the substrate of pain -- the nociceptive signals -- are displayed in the appropriate areas of the brain stem, thalamus, and cerebral cortex and generate an image of pain, a feeling of pain. But note that the "after" process to which I am referring is not beyond the brain, it is very much in the brain and, as far as I can fathom, is just as biophysical as the process that came before. Specifically, in the example above, it is a process that interrelates neural patterns of tissue damage with the neural patterns that stand for you, such that yet another neural pattern can arise -- the neural pattern of you knowing, which is just another name for consciousness. If the latter interrelating process does not take place, you will never know that there was tissue damage in your organism -- if there is no you and there is no knowing, there is no way for you to know, right?

Curiously, if there had been no you, i.e., if you were not conscious and if there had been no self and no knowing relative to hot plates and burning fingers, the wealthy machinery of your self-less brain would still have used the nociceptive neural patterns generated by tissue damage to produce a number of useful responses. For instance, the organism would have been able to withdraw the arm and hand from the source of heat within hundreds of milliseconds of the beginning of tissue damage, a reflex process mediated by the central nervous system. But notice in the previous sentence I said "organism" rather than "you." Without knowing and self, it would not have been quite "you" withdrawing the arm. Under those circumstances, the reflex would belong to the organism but not necessarily to "you." Moreover, a number of emotional responses would be engaged automatically, producing changes in facial expression and posture, along with changes in heart rate and control of blood circulation -- we do not learn to wince with pain, we just wince. Although all of these responses, simple and not so simple, occur reliably in comparable situations in all conscious human beings, consciousness is not needed at all for the responses to take place. For instance, many of these responses are present even in comatose patients in whom consciousness is suspended....

Tissue damage causes neural patterns on the basis of which your organism is in a state of pain. If you are conscious, those same patterns can also allow you to know you have pain. But whether or not you are conscious, tissue damage and the ensuing sensory patterns also cause the variety of automated responses outlined above, from a simple limb withdrawal to a complicated negative emotion. In short, pain and emotion are not the same thing.

You may wonder how the above distinction can be made, and I can give you a large body of evidence in its support. I will begin with ... [a patient] suffering from a severe case of refractory trigeminal neuralgia ... This is a condition involving the nerve that supplies signals for face sensation in which even innocent stimuli, such as a light touch of the skin of the face or a sudden breeze, trigger an excruciating pain. ... As a last resort, the neurosurgeon Almeida Lima ... offered to operate on him, because producing small lesions in a specific sector of the frontal lobe had been shown to alleviate pain ...

[T]wo days after the operation ... he had become an entirely different person, relaxed, happily absorbed in a game of cards with a companion in his hospital room. When Lima asked him about the pain, he looked up and said quite cheerfully that "the pains were the same," but that he felt fine now. ... The operation had done little or nothing to the sensory patterns corresponding to local tissue dysfunction that were being supplied by the trigeminal system. The mental images of that tissue dysfunction were not altered and that is why the patient could report that the pains were the same. And yet the operation had been a success. It had certainly abolished the emotional reactions that the sensory patterns of tissue dysfunction had been engendering. Suffering was gone. The facial expression, the voice, and the general deportment of this man were not those one associates with pain.

The point is that the sensing of negative stimuli that we would consider painful isn't ethically relevant if there is no "mind" there feeling the feeling.

Evolution vs. Complexity

Being able to sense and react to stimuli, as well as regulate one's internal state, has significant evolutionary advantages. Being able to have subjective, conscious experiences -- which requires additional neural mechanisms -- isn't necessary. If a system can get by with a computer-like input/output relation to the world, why wouldn't they? Why would organisms spend resources on something they don't need? Evolution isn't inefficient.

Indeed, a common question isn't so much how consciousness arose, but rather: Why? David Chalmers makes this point when he insists on calling consciousness (as opposed to sentience) "The Hard Problem."

In Kinds of Minds, Daniel Dennett contends that only higher social mammals are actually conscious -- that is, more than automatons. He argues that from an evolutionary perspective, actual subjective consciousness -- is only useful in being able to understand the thought process within another's mind. That is, in short, actual subjective experience only make sense in terms of being empathic. [Yes, he comments that this conclusion is awfully convenient.]

Damasio contends that consciousness is useful only to long-lived beings that are able to use the suffering to significantly alter behavior so as to allow for healing.

[P]ain, which I regarded as one of the main determinants of the course of biological and cultural evolution, may have begun as an afterthought of nature, an attempt to deal with a problem that has already arisen. I used to think of pain as putting a good lock on the door after a house has been robbed, but Pierre Rainville has suggested a better metaphor to me: putting a body-guard in front of the house while you repair the broken window. After all, pain does not result in preventing yet another injury, but rather in protecting the injured tissue, facilitating tissue repair, and avoiding infection of the wound.

However, this itself doesn't argue, necessarily, for conscious awareness. In more general terms, he concludes:

What is consciousness really good for, considering that so much adequate regulation of life can be achieved without conscious processing, that skills can be automated and preferences enacted without the influence of a knowing self? The simplest answer: consciousness is good for extending the mind's reach and, in so doing, improving the life of the organism whose mind has that higher reach.

Creatures with consciousness have some advantages over those that do not have consciousness. They can establish a link between the world of automatic regulation (the world of basic homeostasis that is interwoven with the proto-self) and the world of imagination (the world in which images of different modalities can be combined to produce novel images of situations that have not yet happened). [See also App. A.]

Ethically, I believe that we are compelled to err on the side of caution in terms of causing possible suffering. But in terms of the actual scientific truth, Occum's Razor would indicate that it would make more sense to ask if subjective consciousness is the simplest explanation. Because of this, it would not be prudent to claim certainty in any of the questions involved in ethical decisions. (For a further discussion of strategic advocacy, see Fish, Consciousness, and Advocacy)

Appendices

from Damasio's The Feeling of What Happens

Appendix A

What is Consciousness?

I suggest that the highly constrained ebb and flow of internal organism states, which is innately controlled by the brain and continuously signaled in the brain, constitutes the backdrop for the mind, and, more specifically, the foundation for the elusive entity we designate as self. I also suggest that those internal states -- which occur naturally along a range whose poles are pain and pleasure, and are caused by either internal or external objects and events -- become unwitting nonverbal signifiers of the goodness or badness of situations relative to the organism's inherent set of values. I suspect that in earlier stages of evolution these states -- including all those we classify as emotions -- were entirely unknown to the organisms producing them. The states were regulatory and that was enough; they produced some advantageous actions, internally or externally, or they assisted indirectly the production of such actions by making them more propitious. But the organisms carrying out these complicated operations knew nothing of the existence of those operations and actions since they did not even know, in the proper sense of the word, of their own existence as individuals. True enough, organisms had a body and a brain, and brains had some representation of the body. Life was there, and the representation of life was there, too, but the potential and rightful owner of each individual life had no knowledge that life existed because nature had no invented an owner yet. There was being but not knowing. Consciousness had not begun.

Consciousness is the rite of passage which allows an organism armed with the ability to regulate its metabolism, with innate reflexes, and with the form of learning known as conditioning, to become a minded organism, the kind of organism in which responses are shaped by a mental concern over the organism's own life.

Consciousness beings when brains acquire the power, the simple power I must add, of telling a story without words, the story that there is life ticking away in an organism, and that the states of the living organism, within body bounds, are continuously being altered by encounters with objects or events in its environment, or, for that matter, by thoughts and by internal adjustments of the life process. Consciousness emerges when this primordial story -- the story of an object causally changing the state of the body -- can be told using the universal nonverbal vocabulary of body signals. The apparent self emerges as the feeling of a feeling.

Consciousness is valuable because it introduces a new means of achieving homeostasis. I am not referring to a more efficient means of balancing the internal milieu than the entirely non conscious machinery we have long had in place in the brain stem and hypothalamus. Rather, I am referring to a new means of solving different kinds of problems that are connected, nonetheless, to the problems solved by previously existing means of homeostatic regulation. In other words, devices in the brain stem and hypothalamus can coordinate, non consciously and with great efficiency, the jobs of the heart, lungs, kidneys, endocrine system, and immunological system such that the parameters that permit life are maintained within the adequate range, while the devices of consciousness handle the problem of how an individual organism may cope with environmental challenges not predicted in its basic design such that the conditions fundamental for survival can still be met.

Consciousness is not the sole means of generating adequate responses to an environment and thus achieving homeostasis. Consciousness is just the latest and most sophisticated means of doing so, and it performs its function by making way for the creation of novel responses in the sort of environment which an organism has not been designed to match, in terms of automated responses.

In rank order, core consciousness sits above, but not far from, other foundational capacities, such as action, emotion, and sensory representation, which we share with several nonhuman species.

The essence of those foundational capacities has probably changed little when we compare the human version to the nonhuman. For example, I see no evidence that emotion has become "better" in humans.

In conclusion, in its normal and optimal operation, core consciousness is the process of achieving a neural and mental pattern which brings together, in about the same instant, the pattern for the object, the pattern for the organism, and the pattern for the relationship between the two. The emergence of each of those patterns and their conjoining in time depends on the contributions of individual brain sites working in close cooperation....

I would say that the effectiveness of consciousness comes from its unabashed connection to the nonconscious proto-self. This is the connection that guarantees that proper attention is paid to the matters of individual life by creating a concern. Perhaps the secret behind the efficacy of consciousness comes from the effective connection it establishes between the biological machinery of individual life regulation and the biological machinery of thought. That connection is the basis for the creation of an individual concern which permeates all aspects of thought processing, focuses all problem-solving activities, and inspires the ensuing solutions. Consciousness is valuable because it centers knowledge on the life of an individual organism.

From its humble beginnings to its current estate, consciousness is a revelation of existence -- a partial revelation, I must add. At some point in its development, with the help of memory, reasoning, and later, language, consciousness also becomes a means to modify existence.

Appendix B

More on the Distinction between Feeling and Awareness

Emotion was probably set in evolution before the dawn of consciousness and surfaces in each of us as a result of inducers we often do not recognize consciously.... For example, we often realize quite suddenly, in a given situation, that we feel anxious or uncomfortable, pleased or relaxed, and it is apparent that the particular state of feeling we know then has not begun on the moment of knowing but rather sometime before. Neither the feeling state nor the emotion that led to it has been "in consciousness," and yet they have been unfolding as biological processes. These distinctions may sound artificial, at first glance, although my purpose is not to complicate something simple but rather to break down, in approachable parts, something that is quite complicated. For the purposes of investigating these phenomena, I separate three stages of processing along a continuum: a state of emotion, which can be triggered and executed non consciously; a state of feeling, which can be represented nonconsiously; and a state of feeling made conscious, i.e., know to the organism having both emotion and feeling. I believe these distinctions are helpful as we try to imagine the neural underpinnings of this chain of events in humans. Moreover, I suspect that some nonhuman creatures that exhibit emotions but are unlikely to have the sort of consciousness we have may well form the representations we call feelings without knowing they do so.

[T]he urge to stay alive is not a modern development. it is not a property of humans alone. In some fashion or other, from simple to complex, most living organisms exhibit it. What does vary is the degree to which organisms know about that urge. Few do. But the urge is still there whether organisms know of it or not.

Appendix C

Behavior, Pain, and Pleasure

What qualifies as an emotion? Does pain? Does a startle reflex? Neither does, but if not, why not? The closeness of these related phenomena calls for sharp distinctions but the differences tend to be ignored. Startle reflexes are part of the repertoire of regulatory responses available to complex organisms and are made up of simple behaviors (e.g., limb withdrawal). They may be included among the numerous and concerted responses that constitute an emotion -- endocrine responses, multiple visceral responses, multiple musculoskeletal responses, and so on. But even the simple emotive behavior of the Aplysia is more complicated than a simple startle reflex.

The point to retain here is the possible interrelationship between pain and pleasure and the attending emotions, as well as the fact that they are not the mirror image of each other. They are different and asymmetric physiological states, which underlie different perceptual qualities destined to help with the solution of very different problems. ... In the case of pain, the problem is coping with the loss of integrity of living tissue as a result of injury, be it internally caused by natural disease or externally induced by the attack of a predator or by an accident. In the case of pleasure, the problem is to lead an organism to attitudes and behaviors that are conducive to the maintenance of its homeostasis.

Pleasure, on the other hand, is all about forethought. It is related to the clever anticipation of what can be done not to have a problem. At this basic level, nature found a wonderful solution: it seduces us into good behavior.

Pain and pleasure are thus part of two different genealogies of life regulation. Pain is aligned with punishment and is associated with behaviors such as withdrawing or freezing. Pleasure, on the other hand, is aligned with reward and is associated with behaviors such as seeking and approaching.

This fundamental duality is apparent in a creature as simple and presumably as nonconscious as a sea anemone. Its organism, devoid of brain and equipped only with a simple nervous system, is little more than a gut with two openings, animated by two sets of muscles, some circular, the others lengthwise. The circumstances surrounding the sea anemone determine what its entire organism does; open up to the world like a blossoming flower -- at which point water and nutrients enter its body and supply it with energy -- or close itself in a contracted flat pack, small, withdrawn, and nearly imperceptible to others. The essence of joy and sadness, of approach and avoidance, of vulnerability and safety, are as apparent in this simple dichotomy of brainless behavior as they are in the mercurial emotional changes of a child at play.

Appendix D

Consciousness and Language

In the case of humans the second-order nonverbal narrative of consciousness can be converted into language immediately. ... That is in the nature of the human, languaged creature. This uninhibitable verbal translation, the fact that knowing and core self also become verbally present in our minds by the time we usually focus on them, is probably the source of the notion that consciousness might be explainable by language alone. It has been thought that consciousness occurred when, and only when, language commented on the mental situation for us.

Curiously, the very nature of language argues against it having a primary role in consciousness. Words and sentences denote entities, actions, events, and relationships. Words and sentences translate concepts, and concepts consist of the nonlanguage idea of what things, actions, events, and relationships are. Of necessity, concepts precede words and sentences in both the evolution of the species and the daily experience of each and every one of us. ... So when my mind says "I" or "me," it is translating, easily and effortlessly, the nonlanguage concept of the organism that is mine, of the self that is mine. ...

One could argue, in fact, that the consistent content of the verbal narrative of consciousness -- regardless of the vagaries of its form -- permits one to deduce the presence of equally consistent nonverbal, imaged narrative that I am proposing as the foundation of consciousness.

The narrative of the state of the proto-self being changed by the interaction with an object much first occur in its nonlanguage form it is ever to be translated by suitable words.