Are animals with simpler brains less sentient?

Original text Luciano Carlos Cunha · Volume VI, p. 25 of the PDF edition · English translation

8.1. The view that there are degrees of sentience

One view sometimes defended is that animals with simpler brains are less sentient than animals with more complex brains²⁷. For the same reason, this view also holds that there are stages in the life of one and the same individual at which they are less sentient, as in the case of a fetus that is already sentient and in cases of dementia²⁸.

Those who adopt this view usually also hold that, for this reason, it would be justified to rank the moral consideration owed to animals hierarchically: humans at the top, then the other primates, then the other mammals, and so on. This view is also used to argue that we should give greater consideration to adults than to young animals. However, as we will see in the following sections, this view conflates three distinct concepts that are not necessarily related²⁹: sentience, valence, and cognition³⁰.

There are different things someone might mean when claiming that some beings are more sentient than others, depending on how they are using the word sentience. Sometimes this word is used as a synonym for the capacity to have experiences (that is, for there being someone "in there"). At other times, it is used to refer to the capacity not only to have experiences but also to recognize certain experiences as positive and others as negative. For example, if there were a being capable of experiences but who experienced all of them as neutral (that is, neither as positive nor as negative), that being would be sentient according to the first sense of the term, but not according to the second. In what follows we will examine the claim that certain animals are more sentient than others, taking these various possible interpretations into account.

8.2. Sentience

Suppose the word sentience is being used to mean the capacity to have experiences. In this sense, it is the difference between being something and being someone. A shoe is something because it is not capable of experiences; it has no consciousness. There is no point of view of the shoe. What a human, a chicken, a fish, a lobster, and a bee have in common, by contrast, is that they are sentient: there is someone "inside" those bodies; they are conscious.

However, if this is the sense in which the term is being used, it makes no sense to speak of degrees of sentience, because in this sense sentience is a binary matter: either one is sentient or one is not. There are no degrees of how much one is a thing or of how much one is someone. A being with a very simple brain is just as much someone as a being with a very complex brain.

8.3. Valence

What do exist are degrees of valence, which concern how positive or negative experiences are. For example, if I lightly bump my arm against the wall, I will feel mild pain, but if I break a leg, I will feel intense pain. As we have seen, this is one possible interpretation of what someone might mean when claiming that certain beings are more sentient than others. That is, they might mean that some are capable of more intense experiences than others.

However, the fact that there are experiences of different intensities does not necessarily imply that, when we compare the sensations two kinds of beings are feeling, one of them will always have the more intense sensation. For example, suppose that one day a human breaks a leg and a pig suffers a light scratch. In this case, the sensation the human is feeling is more intense. However, suppose that the next day the opposite happens. In that case, the sensation the pig feels is more intense.

Of course, it is quite possible that different beings have experiences of different intensities in response to the same stimulus. Perhaps this is what some people who claim that some beings are more sentient than others mean. However, let us remember that the view we are discussing makes a second claim: that the intensity of a sensation is proportional to the degree of cognition. However, the one does not necessarily follow from the other. That is, it is possible that there are beings who feel more intensely than others in response to the same stimulus, but that it is not the being with the greater cognitive capacity who feels more intensely, but rather the reverse. For example, a slap of the same intensity given to an adult and to a baby will probably hurt the baby much more, and this is so even though adults have a much higher degree of cognition.

Are there animals that feel more intensely than others, in response to the same stimulus, in all situations? It is possible, but most probably in the opposite way from that presupposed by the view we are discussing. For evolutionary reasons, it is quite possible that less complex brains feel more intensely. Below we will see why.

The capacity to have positive and negative experiences is directly linked to the motivation for behavior. That is, the fact that sentient beings experience certain stimuli as positive and others as negative leads them to seek the former and avoid the latter. This capacity also confers advantages in terms of survival. Survival to sexual maturity, in turn, helps increase the chances that they will reproduce and pass this trait on to the next generations.

Because of selective pressure, it is quite possible that experiences are more intense at stages when the animal has not yet developed certain cognitive capacities (for example, when it is still young, or even before it is born or hatches, as long as its nervous system is already formed). This is because at these stages, since the animal has not yet developed its cognitive capacities, the only motivation it would have for its behavior and learning would be to avoid negative experiences and seek positive ones³¹.

This is especially true in the case of precocial animals, since they need to be quite active in order to break the shell and hatch, and also to have any chance of surviving after hatching³², given that in most oviparous species the young receive no parental care. If these animals did not have the capacity to feel keenly at this age, these species would very probably no longer exist (since probably all of them would have died before sexual maturity, without leaving any offspring). So the fact that these species still exist (together with the fact that these animals already have a formed nervous system at this stage and behave in certain ways) is a reason to suppose that their members are capable of feeling very

keenly. That is, because of selective pressure, it is quite possible that animals with less developed cognitive capacities feel even more intensely. This holds both if we compare adults and young of the same species and if we compare animals of different species.

8.4. Degree of cognition

The degree of cognition, on the other hand, is something else entirely. It concerns how intelligent a given animal is. This does not make one animal more sentient, or less sentient, than another (in the sense of being someone). Beings of little intelligence are just as much someone as highly intelligent beings. We have also seen that their lower intelligence does not make their experiences less intense either. As we saw in the previous paragraph, they may be even more intense. The psychologist Richard Ryder, who coined the term speciesism, emphasizes this point: "Their experiences may be simpler than ours, but are they any less intense? Perhaps the primitive pain a caterpillar feels when it is crushed is greater than our more sophisticated sufferings³³"

Of course, there are certain ways of being harmed that depend on one's cognitive capacity. For example, only someone who understands that they are going to die in a few hours is capable of suffering in anticipation of their death. Only beings who remember past negative events can suffer because of them. However, as the case of babies illustrates, there are many other contexts in which it is lesser cognitive capacity that entails greater suffering. In short, there is no necessary correlation between greater cognitive capacity and more intense experience.

8.5. Intelligentism

In the previous section we saw that it is a mistake to infer, from the fact that one being is cognitively more sophisticated than another, that it is therefore capable of feeling more intensely. However, there is another position that is sometimes defended by pointing out that certain animals are cognitively more sophisticated than others. This position holds that

these animals should receive greater moral consideration, even while acknowledging that they are not capable of feeling more intensely.

Basically, what this position holds is that cognitively more sophisticated beings should have a special status. This special status would mean, for example, that when faced with harms of similar magnitude, we should give priority to helping the cognitively more sophisticated individual. Depending on how much higher this status was, some variants of this position would hold that we should give priority to cognitively more sophisticated beings even when the harm they suffer is smaller.

Now, this view is like speciesism, racism, and sexism, except that it uses the degree of cognition as its criterion. It is biased for at least two reasons. First, because it violates the principle of equal consideration by assigning different weight to similar levels of harms and benefits on the basis of a factor that depends on the natural lottery (and therefore implies neither blame nor merit). Second, such a position does not pass the impartiality test, since it would not be approved by rational beings if they did not know what cognitive level they would have after being born. It is, therefore, a form of discrimination that could appropriately be called intelligentism, by analogy with speciesism.

8.6. Conclusion

If what has been argued above is correct, there is no way to justify giving less consideration to cognitively less capable beings. This is so for three reasons. First, we saw that these beings are just as much someone as any other sentient being. Second, we also saw that there are no good reasons to suppose that their lesser cognitive capacity means that they feel less intensely. Finally, third, we saw that there seems to be no justification for assigning a privileged moral status to cognitively more capable beings³⁴.