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Introduction to Animal Rights - Part II

Updated: Apr 15, 2022

In Part I, we argued that we should empathize with the suffering of animals, and we developed the idea of the expanding circle of moral consideration.

In this second part, we will develop a rational argument that shows that animals have intrinsic value, and as a result, they should be given legal rights.

The argument from marginal cases

Perhaps the best way of showing why the argument for the sole moral consideration of humans fails is the so-called argument from marginal cases, also known as the argument from species overlap.

Let's say that a person defends that only human beings deserve moral consideration because only humans have a capacity X. This capacity X could be: reason, intelligence, autonomy, the use of language, or the use of tools, among other similar features and capabilities. This person believes that only human beings are morally valuable because they are the only ones who possess a certain capability or feature.

Therefore, the argument of those who do not believe that animals should have rights follows this structure:

  1. Human beings have a capacity X, such as intelligence, autonomy, use of language, etc.

  2. Animals do not have such capacity X.

  3. Capacity X is morally relevant as a criterion of moral consideration.

  4. Therefore, only humans, and not animals, deserve moral consideration.

However, those of us who defend that animals have rights argue that this reasoning is flawed at every step. Let's see why by looking at this type of reasoning in more depth.

Objection to point 1: Not all human beings have capacity X

If we were to say that the source of moral consideration is a capacity such as reason, intelligence, autonomy, the use of language, or the use of tools, we would see that some beings that we want to consider as human beings or beings with rights would not actually have rights.

This category of human beings without rights would include newborn babies, those with severe mental disabilities or in a coma, and the senile elderly who have lost most of their abilities. These are the so-called marginal cases that give the argument its name.

Under such criteria, none of these people have rights. In fact, under some criteria, lacking autonomy, agency, or reason, they would not even count morally as a "person", but would simply be beings of the Homo sapiens species without being persons or human beings. [i]

Objection to point 2: Some animals have capacities X

On the other hand, animals like chimpanzees are able to use tools, dolphins and whales are able to communicate with each other, and some apes have been taught some basic notions of sign language.

In addition, there are capacities that animals have but that humans lack, such as the ability to distinguish between rocks and food on the seafloor, an ability that fish, seals, and other marine animals have. Or the ability to use ultrasound to orient ourselves in the dark, like bats. Why give such an importance to the use of tools or communication, for example, when for many beings the ability to find food in their environment or move in the dark is much more relevant and important? Deep down, our criteria are partial and biased and do not outline a morally relevant criterion.

Another objection to point 2: Lowering the bar is problematic

If we "lower the bar" on criterion X in such a way that it is broader, to try to include newborn babies, those with severe mental disabilities, those in a coma, and those senile elderly who have lost most of their capabilities in our circle of moral consideration, we would have to use a characteristic X that all humans fulfill. Such an ability could be the ability to move, eat, breathe, and so on.

But in order to defend the superiority of human beings and exclude animals, these criteria would not work. If we lower the bar, like saying that such capacity X is to be able to breathe, have life, or a similar capacity to be able to declare that human beings in a coma have rights, then we would have to accept that almost all animals deserve rights.

In order to avoid this issue, the person that argues that animals don't have rights would have to find a capacity that a comatose human fulfills but that no animal has.

The challenge that we pose is that there is no such capacity X that all humans have but all non-human animals lack. A chimpanzee has more capabilities in almost every way (it is able to move, search for food, socialize, play, feel pain, frustration and happiness, create tools...) than a human in a coma.

Objection to point 3: Most capacities X are morally irrelevant

However, those of us who defend animal rights believe that the error is even deeper than what we have presented so far.

The deeper mistake is that such capacities X that those who consider that animals do not deserve rights are choosing are profoundly arbitrary and have nothing to do with moral worth.

These people should have and offer more arguments on why the fact of having more intelligence, reason, autonomy, use of language, or use of tools confers more rights or deprives those who do not have them of rights.

There is no clear reason why the ability to reason or use tools should be what sets humans apart from other animals. There are no rational arguments to defend such a position, they are simply justifications to continue with our exploitation and mistreatment of animals.

Objection to point 4: Rejecting speciesism

Therefore, the argument of those who believe that animals have no rights fails, and the conclusion is that we must reject discrimination based on species membership. Today, this type of discrimination is called speciesism, in analogy to racism or sexism.

People with racist beliefs or behaviors believe that those of a different race deserve fewer rights, or that their interests should be considered less important or null. However, race is not a criterion of moral distinction to which we should give credibility or weight.

To show that it has no weight, it is only necessary to ask for the rational justification for the use of this criterion. People with racist beliefs will not be able to give a good argument for such discrimination. In the same way, as we have shown, people with speciesist beliefs cannot give a good argument for their discrimination. All these types of discrimination are arbitrary. Speciesism, like racism, is a type of unjustified discrimination.

Abandoning Moral Anthropocentrism: Sentiocentrism

If we have to elaborate on our concrete position to defend animal rights, we consider that the capacity to have experiences of suffering (pain, frustration) or enjoyment (happiness, pleasure, satisfaction) creates the basis that leads a living being to have needs, wants, and interests.

This, in turn, lays the groundwork for conferring fundamental rights on the beings involved. Animals, as sentient beings, want to be able to live peacefully with their families, as well as play and receive pleasant stimuli, like all of us. They do not want to live locked up or under conditions of stress and suffering.

This is what is called in legal philosophy as the interest theory of rights, defended by renowned thinkers such as Jeremy Bentham, John Stuart Mill, John Austin, John Finnis, and Joseph Raz, among others. Many living beings have diverse interests, and this is what the law and the law should be dedicated to protecting. As Jeremy Bentham wrote in 1789:

"The day may come when the rest of the animal creation may acquire those rights which never could have been witholden from them but by the hand of tyranny. The French have already discovered that the blackness of the skin is no reason a human being should be abandoned without redress to the caprice of a tormentor. It may one day come to be recognised that the number of the legs, the villosity of the skin, or the termination of the os sacrum are reasons equally insufficient for abandoning a sensitive being to the same fate. What else is it that should trace the insuperable line? Is it the faculty of reason or perhaps the faculty of discourse? But a full-grown horse or dog, is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day or a week or even a month, old. But suppose the case were otherwise, what would it avail? The question is not, Can they reason? nor, Can they talk? but, Can they suffer?" - Jeremy Bentham, An Introduction to the Principles of Morals and Legislation (1789)

That is why the correct theory on moral consideration is sentiocentrism, that is, certain rights must be granted to those beings capable of having positive or negative sensations. Animals are someone, not something. The suffering and pain suffered by a sentient being must be taken morally into consideration and protected by law and law in all places and countries of the world.

What can we do?

In Part 3, we outline the things we can do to help animals, as well as provide a bibliography to read more about this topic.


[i] For example, under the criteria of some of the most important legal philosophers, such as the criteria of HLA Hart or that of John Rawls, severely disabled people would not count as a person.

In Hart's case, because they lack autonomy, the ability to make free decisions.

  • See Hart, HLA (1955) "Are there any natural rights?" Philosophical Review 64 (2). 175-191.

In Rawls's case, by lacking an understanding of the good life and are not living cooperatively with others.

  • See Rawls, J. (1971). A Theory of Justice.


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