Do Animals Feel Pain?

Do animals feel pain? How can we acquire knowledge about this? How can we even know that a being—whether human or any other animal—is suffering? We know that we ourselves are sometimes in a state of suffering, and we perceive this feeling directly; for example, when someone presses a lit cigarette onto the back of our hand, we feel a burning sensation and pain, and we perceive this directly as well. But by what means can we find out that another being is suffering—whether that being is our friend or a stray dog. Suffering is a subjective and internal (conscious) event, and for this reason it cannot be grasped through outward sense. Behaviors such as screaming, writhing, and pulling one's hand away from under a lit cigarette are signs of suffering, but they are not suffering itself. Even the cases presented and recorded by a neurologist from neural activities and brain observations do not signify suffering itself. Suffering is something we feel and perceive, and the only thing we can do is to reason that just as we ourselves feel suffering, other individuals also feel suffering in various ways and through specific events, and it is because of this infliction of suffering that they exhibit signs and behaviors.

Do Animals Feel Pain?

Introduction

In the brief writing we are reviewing, the renowned contemporary thinker Peter Singer attempts to concisely draw our attention to the important point that animals—who, alongside us humans, are among the principal inhabitants of the Earth—possess the capacity for perception and feel pain. The belief that animals have this level of perception can have numerous theoretical and practical consequences and has even led to the emergence of movements. The present writing is originally excerpted from a section of the book Animal Liberation, second edition, 1990, New York: Avon Books, pp. 10-12.

Do animals feel pain? How can we acquire knowledge about this? How can we even know that a being—whether human or any other animal—is suffering? We know that we ourselves are sometimes in a state of suffering, and we perceive this feeling directly; for example, when someone presses a lit cigarette onto the back of our hand, we feel a burning sensation and pain, and we perceive this directly as well. But by what means can we find out that another being is suffering—whether that being is our friend or a stray dog. Suffering is a subjective and internal (conscious) event, and for this reason it cannot be grasped through outward sense. Behaviors such as screaming, writhing, and pulling one's hand away from under a lit cigarette are signs of suffering, but they are not suffering itself. Even the cases presented and recorded by a neurologist from neural activities and brain observations do not signify suffering itself. Suffering is something we feel and perceive, and the only thing we can do is to reason that just as we ourselves feel suffering, other individuals also feel suffering in various ways and through specific events, and it is because of this infliction of suffering that they exhibit signs and behaviors.

If the assumption that "other humans feel suffering just as we do" is justifiable, then would it not also be justifiable to reason that other animals feel suffering? Almost by the same method through which we find out that other humans are suffering (that is, through observing external signs), we can likewise find out that other beings, including animals, are suffering, and we can observe these instances among animals, especially in the mammals and birds that live around us.

Behavioral signs such as writhing, howling, repeated barking, whimpering, and the expression of various sounds are attempts to express pain and also to distance themselves from and avoid suffering. When animals encounter things that have previously caused them suffering and pain, they also try, by exhibiting certain behaviors, to show that they are averse to approaching those things. Furthermore, we know that these animals have a nervous system very similar to ours, such that when confronted with things that cause us humans to suffer, they also feel suffering and become afflicted. In animals, as in us humans, when faced with painful stimuli, blood pressure rises, trembling and shaking appear in their limbs, the heart rate increases, and when the painful stimulus persists, their blood pressure drops. Although the cerebral cortex of humans is much more complex and advanced than that of other animals, this part of the brain relates to the functions of thought and reflection, not to basic sensations, perceptions, and stimulations. These stimulations, basic sensations, and such perceptions are located in the midbrain (diencephalon), which is also quite advanced in other animals—especially in mammals and birds.[1]

Also, today we know full well that the nervous system of animals is not an artificial, fabricated, and cobbled-together system—like robots—that merely feigns suffering when struck and imitates behaviors similar to those of humans. The nervous system of animals works in the same way that our nervous system works, and in fact, the evolutionary history of humans and animals—especially mammals—shows that the nervous systems of humans and animals originated from a common point and then followed different paths. The capacity to feel and perceive suffering aids the survival of a living being because the feeling of suffering causes the animal to avoid sources and origins of pain. It would certainly be unreasonable and unacceptable to suppose that a nervous system that is entirely equivalent physiologically, having the same foundations and the same functions, would produce behaviors that are merely mimicked identically; rather, the level of consciousness and the structures of animals must also be taken into consideration.

Most scientists working in this field agree with this statement. Lord Brain, one of the most important neurologists of our time, says in this regard:

"I personally do not accept at all that we should acknowledge the possession of memory and mind only in humans and deny the existence of these in other animals. The least I can say is that I personally have no doubt that the interests and activities of animals are accompanied by consciousness and feeling, which in this respect are completely identical to us humans, although their level of perception is somewhat lower. However, the very principle of animals having consciousness and feelings is completely evident and obvious to me." [2]

The author of the book "On Suffering" writes:

All the main reasons confirm that vertebrate mammals possess exactly the same type of feeling that exists in humans—the feeling of pain and suffering—and consequently, they feel pain and suffering. If we say that animals, because they are at a lower level, therefore do not perceive suffering or that their degree of suffering perception is slight, we have spoken a frivolous word. It can very easily be shown that some senses in animals are not only not weaker, but on the contrary, those senses are entirely sharper and more sensitive. Those animals express feelings and react to environmental events much more alertly than we humans do. Regardless of the complexities of the cerebral cortex (which does not directly perceive suffering), the nervous system of animals is equivalent to our human nervous system, and the reactions they show to inflicted suffering are very similar to our human reactions—although, as far as we know, animals lack and are deprived of the aspects of having philosophical abilities and thoughts. The factor of feeling is a decisive and very obvious factor, especially in the face of fear and anger.[3]

It seems the discussion on this matter is sufficient up to this point, but it appears necessary to conclude by providing an answer to one major objection:

Throughout the history of philosophy, there appears to be a vague line of thought, which also has affinities with the thinking of the renowned and influential modern philosopher Wittgenstein, namely that perhaps we cannot meaningfully apply the title of conscious and sentient animal to animals that lack the attribute of "having a language that conveys consciousness." However, this approach does not seem reasonable to me at all. Perhaps at some levels and stages, having language is necessary for abstract thought, but the stage of perceiving suffering is a primary one and has nothing to do with having or not having language.

Human infants and young children also lack a language by which they can express their states concerning the onset and occurrence of suffering. Now my question is, "Can we, and are we permitted to, deny the occurrence of suffering and the experience of pain in infants and those children?" If your answer is negative, then we conclude that having language is not so important after all.

So my final word to state the conclusion is that we have no good scientific or philosophical reason to deny suffering in the animal world. If we have no doubt that some animals perceive suffering, then we cannot deny the existence of suffering and the feeling of pain in other animals and even in other beings. My final word is this: Animals feel pain.

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Do Animals Feel Pain?

by Peter Singer

Excerpted from Animal Liberation, 2nd edition, New York: Avon Books, 1990, pp. 10-12, 14-15

Nearly all the external signs that lead us to infer pain in other humans can be seen in other species, especially the species most closely related to us--the species of mammals and birds. The behavioral signs include writhing, facial contortions, moaning, yelping or other forms of calling, attempts to avoid the source of the pain, appearance of fear at the prospect of its repetition, and so on. In addition, we know that these animals have nervous systems very like ours, which respond physiologically like ours do when the animal is in circumstances in which we would feel pain: an initial rise of blood pressure, dilated pupils, perspiration, an increased pulse rate, and, if the stimulus continues, a fall in blood pressure. Although human beings have a more developed cerebral cortex than other animals, this part of the brain is concerned with thinking functions rather than with basic impulses, emotions, and feelings. These impulses, emotions, and feelings are located in the diencephalon, which is well developed in many other species of animals, especially mammals and birds.[1]

We also know that the nervous systems of other animals were not artificially constructed--as a robot might be artificially constructed--to mimic the pain behavior of humans. The nervous systems of animals evolved as our own did, and in fact the evolutionary history of human beings and other animals, especially mammals, did not diverge until the central features of our nervous systems were already in existence. A capacity to feel pain obviously enhances a species' prospects for survival, since it causes members of the species to avoid sources of injury. It is surely unreasonable to suppose that nervous systems that are virtually identical physiologically, have a common origin and a common evolutionary function, and result in similar forms of behavior in similar circumstances should actually operate in an entirely different manner on the level of subjective feelings. […]

The overwhelming majority of scientists who have addressed themselves to this question agree. Lord Brain, one of the most eminent neurologists of our time, has said:

I personally can see no reason for conceding mind to my fellow men and denying it to animals. […] I at least cannot doubt that the interests and activities of animals are correlated with awareness and feeling in the same way as my own, and which may be, for aught I know, just as vivid.[2]

The author of a book on pain writes:

Every particle of factual evidence supports the contention that the higher mammalian vertebrates experience pain sensations at least as acute as our own. To say that they feel less because they are lower animals is an absurdity; it can easily be shown that many of their senses are far more acute that ours--visual acuity in certain birds, hearing in most wild animals, and touch in others; these animals depend more than we do today on the sharpest possible awareness of a hostile environment. Apart from the complexity of the cerebral cortex (which does not directly perceive pain) their nervous systems are almost identical to ours and their reactions to pain remarkably similar, though lacking (so far as we know) the philosophical and moral overtones. The emotional element is all too evident, mainly in the form of fear and anger."[3]

That may well be thought enough to settle the matter; but one more objection needs to be considered. […]

[T]here is a hazy line of philosophical thought, deriving perhaps from some doctrines associated with the influential philosopher Ludwig Wittgenstein, Which maintains that we cannot meaningfully attribute states of consciousness to beings without language. This position seems to me very implausible. Language may be necessary for abstract thought, at some level anyway; but states like pain are more primitive, and have nothing to do with language. […]

Human infants and young children are unable to use language. Are we to deny that a year-old child can suffer? If not, language cannot be crucial. […]

So to conclude: there are no good reasons, scientific or philosophical, for denying that animals feel pain. If we do not doubt that other humans feel pain we should not doubt that other animals do so too.

Animals can feel pain.