Sentiency and Rights: Some Observations

By Tom Regan. Presented at the conference ‘From Darwin to Dawkins: The Science and Implications of Animal Sentience.’ Sponsored by Compassion in World Farming, London, England, March 17 and 18, 2005.

Like many others here, I am a proponent of moral rights, including the moral rights of other-than-human animals. Moreover, as is also true of many of you, I believe that sentiency has an important role to play when it comes to understanding these rights. On this occasion, I want to explore this nexus of ideas: moral rights, sentiency and the latter’s relevance to the former. I begin by highlighting some of the defining characteristics of moral rights.(1)

I. Some Defining Characteristics of Moral Rights

No Trespassing

To possess moral rights is to have a kind of protection we might picture as an invisible “No Trespassing” sign. What does this sign prohibit? Two things. First, others are not morally free to harm us; to say this is to say that others are not free to take our life or injure our body as they please. Second, others are not morally free to interfere with our free choice; to say this is to say that others are not free to limit our free choice as they please. In both cases, the “No Trespassing” sign is meant to protect our most important goods (our life, our body, our liberty) by morally limiting the freedom of others.

Things are different when people exceed their rights by violating ours. When this happens, we act within our rights if we fight back, even if this does some serious harm to the aggressor. However, what we may do in self-defense does not translate into a general permission to hurt those who have not done anything wrong.


Moral rights breathe equality. They are the same for all who have them, differ though we do in many ways. This explains why no human being can justifiably be denied rights for arbitrary, prejudicial, or morally irrelevant reasons. Race is such a reason. To attempt to determine which humans have rights on the basis of race is like trying to sweeten tea by adding salt. What race we are tells us nothing about what rights we have.

The same is no less true of other differences between us. My wife Nancy and I trace our family lineage to different countries; she to Lithuania, I to Ireland. Some of our friends are Christians, some Jews, some Moslems. Others are agnostics or atheists. In the world at large, a few people are very wealthy, many more, very poor. And so it goes. Humans differ in many ways. There is no denying that.

Still, no one who believes in human rights thinks these differences mark fundamental moral divisions. If we mean anything by the idea of human rights, we mean that we have them equally. And we have them equally regardless of our race, gender, religious belief, comparative wealth, intelligence, or date or place of birth, for example.


Every serious advocate of human rights believes that our rights have greater moral weight than other important human values. To use an analogy from the card game Bridge, our moral rights are trump. Here is what this analogy means.

A hand is dealt. Hearts are trump. The first three cards played are the queen of spades, the king of spades, and the ace of spades. You (the last player) have no spades. However, you do have the two of hearts. Because hearts are trump, your lowly two of hearts beats the queen of spades, beats the king of spades, even beats the ace of spades. This is how powerful the trump suit is in the game of Bridge.

The analogy between trump in Bridge and individual rights in morality should be reasonably clear. There are many important values to consider when we make a moral decision. For example: How will we be affected personally as a result of deciding one way or another? What about our family, friends, neighbors, people who live some place else? It is not hard to write a long list. When we say, “rights are trump,” we mean that respect for the rights of individuals is the most important consideration in “the game of morality,” so to speak. In particular, we mean that the benefits others derive from violating someone’s rights never justify violating them.


In a general sense, the rights mentioned above (life, liberty, and bodily integrity) are variations on a main theme, that theme being respect. I show my respect for you by respecting these rights in your life. You show your respect for me by doing the same thing. Respect is the main theme because treating one another with respect just is treating one another in ways that respect our other rights. Our most fundamental right, then, the right that unifies all our other rights, is our right to be treated with respect.

II. Understanding Moral Rights

It is one thing to say what moral rights are and quite another to explain why we have them whereas sticks and stones do not. Given the constraints of time, it will not be possible for me to offer anything like a complete explanation. But permit me to offer a rough sketch of the answer I favor.


Earlier we noted some of the many ways humans differ from one another — in terms of gender, race and ethnicity, for example. Despite our many differences, there are some ways in which all humans who have rights are the same. I do not mean because we all belong to the same species (which is true but not relevant). And I do not mean because we all are persons (which may be relevant but is not true). What I mean is that we are like one another in relevant ways, ways that relate to the rights we have: our rights to life, to bodily integrity, and to liberty.

Think about it. Not only are we all in the world, we all are aware of the world, and aware as well of what happens to us. Moreover, what happens to us — whether to our body, or our freedom, or our life itself — matters to us because it makes a difference to the quality and duration of our life, as experienced by us, whether anybody else cares about this or not. Whatever our differences, these are our fundamental similarities.

We have no commonly used word that names this particular family of similarities. “Human being” does not do the job (a deceased human being is a human being but is not aware of the world, for example). Neither does “person” (human infants are aware of what happens to them but are not persons, at least not in the way philosophers understand this idea). Still, these similarities are important enough to warrant a verbal marker of their own. I use the expression “subject-of-a-life” to refer to them. Given this usage, the author of these words, Tom Regan, is a subject-of-a-life, and so are the people who hear them.

Which humans are subjects-of-a-life? All those humans who have the family of similarities mentioned above. And who might these be? Well, somewhere in the neighborhood of six billion of us, regardless of where we live, how old we are, our race or gender or class, our religious or political beliefs, our level of intelligence, and so on through a very long inventory of our differences.

Why is being the subject-of-a-life an important idea? Because the family of characteristics that define this idea makes us all the same in a way that makes sense of our moral equality. Here is what I mean.

As implied in the preceding, human subjects-of-a-life differ in many ways. These differences are real, and they matter. However, when we think about the world in terms of fundamental moral equality, these differences make no difference. Morally considered, a genius who can play Chopin etudes with one hand tied behind her back does not have a “higher” rank than a serious mentally impaired child who will never know what a piano is or who Chopin was. Morally, we do not carve-up the world in this way, placing the Einsteins in the “superior” category, “above” the “inferior” Homer Simpsons of the world. The less gifted do not exist to serve the interests of the more gifted. The former are not mere things when compared to the latter, to be used as means to their ends. From the moral point of view, each of us is equal because each of us is equally a somebody, not a something, the subject-of-a-life, not a life without a subject.

So why is the idea of being the subject-of-a-life important? Because it illuminates our moral sameness, our moral equality.

As subjects-of-a-life, we are all the same because we are all in the world.

As subjects-of-a-life, we are all the same because we are all aware of the world.

As subjects-of-a-life, we are all the same because what happens to us matters to us.

As subjects-of-a-life what happens to us matters to us because it makes a difference to the quality and duration of our life.

As subjects-of-a-life, there is no superior or inferior, no higher or lower.

As subjects-of-a-life, we are all morally the same–all morally equal.

Needless to say, the forgoing does not constitute a strict proof of our rights. My intention, rather, has been to explain how our being subjects-of-a-life illuminates (how it helps us understand) the underpinnings of our rights, especially our moral equality. It should come as no surprise that I think what I have just said about our rights is no less true of the rights of other animals.

III. Animal Rights

Are any other-than-human animals subjects-of-a-life? Yes, of course. All mammals, at least. All birds, at lest. All fish, at least. Why? Because these beings satisfy the conditions of the kind of subjectivity in question. Like us, they are in the world, aware of the world, and aware of what happens to them. Moreover, what happens to them (to their body, their freedom, their life) matters to them, whether anyone else cares about this or not. Thus do these beings share the rights we have mentioned, including the right to be treated with respect.

I am all too painfully aware, as I know you are too, that some people deny or contest this way of thinking. Animals do not experience anything, some maintain. Or they experience very little, hardly enough to ground the kind of subjectivity I have described. Or (to mention objections from another quarter) no one, human or otherwise, has rights. And so on.

I have addressed these and other relevant challenges on many occasions in the past and do beg leave of them on this one.(2) Here I wish only to mention that respect for the rights of those animals to whom I have referred will have profound, one might even say revolutionary consequences. Respect for these rights means (among other things) more than cutting back on the amount of meat we eat, or avoiding pale veal, or eating only chicken and fish, or being satisfied with providing farmed animals with larger cages. It means an end to commercial animal agriculture, whether intensive or free range. We do not respect the rights of cows and pigs, chickens and geese, tuna and trout by ending their life prematurely, however “humane” the methods used. These animals have a right to life no less certainly than we do. Or so I believe even as I hope all of you will agree. It remains to be asked what role sentiency might play in helping us understand human and animal rights, the right to life in particular.

IV. Two meanings of ‘sentiency’

Some people favor a broad understanding of sentiency, one that equates being sentient with consciousness in any of its myriad manifestations. (3) Given this understanding, beings who think, imagine, remember, act purposefully, feel emotions, and experience pleasure and pain are sentient. More, the same is true of beings who lack all these capacities but who are able to see, hear, and in other ways perceive objects in their physical environment. They are sentient beings, too.

Now, some of these same thinkers maintain that sentiency, in any of its forms, is both necessary and sufficient for having rights. In their view, in other words, all sentient beings have rights and only sentient beings have rights.

I do not think is correct. There is no plausible reason to think that having the capacities to hear or smell by themselves confer rights on anybody or help us understand rights when they are possessed. Granted, if the beings who have these capacities want to be free to use them, or if being denied their use detracts from their welfare, then we may have the beginnings of an argument for recognizing their rights. However, this is not what the broad interpretation of sentiency maintains. It maintains that possession of these perceptual capacities themselves, independent of any other capacity, including wanting or desiring, is sufficient for having rights. Speaking for myself, this seems more than false. It seems plainly false.

Some thinkers prefer a narrow interpretation of sentiency, one that limits it to the capacity to experience pleasure and pain, to suffer and enjoy. (4) Would the presence of this capacity, unlike the capacity for sense perception, help us understand why sentient beings have all the rights we have been discussing, the right to life in particular?

One could argue—in fact I have made this argument in the past (5) — that sentiency in the narrow sense plays a central role in explicating why sentient beings have the right to be spared gratuitous suffering, suffering that cannot be morally justified. Just as it is wrong to cause such suffering in others, so (it can be argued) these others have a right not to be the victims.

Suppose this much is granted. Even if it is, it is hard to understand how the mere capacity to experience pleasure and pain can help us understand why sentient beings all have rights to bodily integrity, liberty and life. Consider this last right in particular. Sentient beings who are killed painlessly have no wrong done to them, have no right of theirs that is violated, if pain is the yardstick of wrong doing. As is true of the broad interpretation of sentiency, therefore, the narrow, hedonic one fails to illuminate (fails to help us understand) why sentient beings have the rights we have been discussing, the right to life in particular.

Where, then, if not the broad or the narrow interpretation, should we turn for greater understanding? Perhaps further reflection on being the subject-of-a-life will offer the needed assistance.

IV. Sentient beings and subjects-of-a-life

Notice, to begin with, that while all subjects-of-a-life are sentient, not all sentient beings are subjects-of-a-life. Beings who are aware of the world (who perceive things in their environment) are sentient; but having this capacity is not sufficient for being a subject-of-a-life (for having an experiential welfare, for example).

Notice, too, that the same is true of having sentiency in the narrow sense.

In our case, for example, our mental life has continuity, a certain unity or solidity over time. We are the same subjects-of-a-life today as we were yesterday and (assuming all goes well) as we will be tomorrow. It is entirely possible that some sentient beings (in the narrow sense) are not like this. We might picture their way of being in the world as akin to soap bubbles. They are here one moment and gone the next. In their case, there was no one for them to be yesterday, and there will be no one for them to be tomorrow.

Logically, there is no reason why some sentient beings (in the narrow sense) cannot be like this. One moment they experience something pleasant and then, like a burst soap bubble, they are gone. The same thing happens when it comes to the experience of pain. One moment they experience something painful and then, like a burst soap bubble, they are gone.

In the case of these sentient beings, then, their mental life lacks the continuity, unity and solidity over time that we find in our case. In their case, unlike ours, they have no sense that they are the same being who is experiencing pain now as the one who experienced pleasure earlier. Why? Because they are not the same being (I mean the same psychological being) in the one case and in the other. Rather, in each case, there is a different, a new (psychological) being who experiences. Sentient beings meeting this description (if there are such), though sentient, are not subjects-of-a-life.

But while, as we have just seen, not all sentient beings are subjects-of-a-life, the reverse is true: all subjects-of-a-life are sentient, given both the broad and narrow interpretations of sentiency. For in so far as subjects-of-a-life are aware of the world (they have sensory perception), the broad understanding captures this capacity shared by all subjects-of-a-life. And in so far as what happens to them matters to them because it makes a difference to the quality of their life, this characteristic of subjects-of-a-life is captured by the narrow understanding as well.

Now, one could say (and perhaps some of you will say) that being the subject-of-a-life represents a third way to interpret sentiency. We might even think of it as a better, a middle way, not as broad as the broad interpretation but also not as narrow as the narrow one. Given this way of thinking, subjects-of-a-life just are sentient beings, and sentient beings just are subjects-of-a-life.

Myself, I have no objection to thinking in these terms provided we are clear about what we are doing if we do so. First, we are saying (in so many words) that both the broad and the narrow interpretations of sentiency are unsatisfactory. Second, we are implying that, because both are unsatisfactory, neither should be relied upon if we argue for the rights of nonhuman animals. And third, we are prescribing a new way to use an old word, not describing how it already is used. If we look up ‘sentient’ and its cognates in any dictionary, we never find words like “what happens to us—whether to our body or our freedom, or our life itself—matters to us” as part of the definition. What we find instead is very much in keeping with the broad interpretation, as in this example: “Sentient . . . 1. Capable of sensation or at least rudimentary consciousness . . . 2a: consciously perceiving: aware . . .”(6)

The plain fact is, ‘sentient’ and its cognates already have established meanings that give “sentient being” a different meaning than “subject-of-a-life.” Of course, we can, if we choose to do so, stipulate that we will henceforth give “sentient being” a new meaning. As to whether we should go down this path is a question I leave for each of us to consider as time and circumstances permit.

For this occasion, then, permit me to conclude as follows. Investigating and understanding the many forms of sentiency found in animals is important for many reasons, including the cause of their liberation from the hands of human tyranny. The great mass of humanity will never change their views about how animals should be treated unless or until they change their views about who (these nonhumans) are. For this very reason, all of us who spend sleepless nights waiting for this day to dawn must be forever grateful to the many scientific and other advances being made in our understanding of animal sentiency. How fortunate we all are, how grateful we all must be, to have the Darwins and Dawkins, yes, and the Bekoffs and Goodalls too, as our mentors and allies.

1. My remarks in Part I are adapted from my Empty Cages: Facing the Challenge of Animal Rights. Rowman and Littlefield, 2004.
2. See, for example, The Case for Animal Rights, 2nd. University of California Press, 2004.
3. Joan Dunayer is a proponent of the broad interpretation. See her Speciesism. Lantern Books, 2005.
4. Peter Singer is a proponent of the narrow interpretation. See his Animal Liberation. Avon Books, 1975.
5. See, for example, my The Moral Basis of Vegetarianism, Canadian Journal of Philosophy, Fall: 1975.
6. Webster’s Third New International Dictionary of the English Language, 1961.