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If the robots we invent in the future are sentient, what rights will we grant them?
If the robots we invent in the future are sentient, what rights will we grant them?
Tabatha Fireman/Getty Images for Eurostar

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Should animals, plants, and robots have the same rights as you?

How humanity’s idea of who deserves moral concern has grown — and will keep growing.

Sigal Samuel is a senior reporter for Vox’s Future Perfect and co-host of the Future Perfect podcast. She writes primarily about the future of consciousness, tracking advances in artificial intelligence and neuroscience and their staggering ethical implications. Before joining Vox, Sigal was the religion editor at the Atlantic.

Everyone reading this sentence likely (hopefully!) agrees that women deserve the same rights as men. But just a couple of centuries ago, that idea would’ve been dismissed as absurd.

The same is true for the belief that black people should have the same rights as white people. Commonly accepted now; unthinkable a couple of centuries ago.

There’s a concept from philosophy that describes this evolution — it’s called humanity’s expanding moral circle. The circle is the imaginary boundary we draw around those we consider worthy of moral consideration. Over the centuries, it’s expanded to include many people who were previously left out of it. As they were brought into the circle, those people won rights. Slavery was abolished. Women got the vote. Same-sex marriage was legalized.

The moral circle is a fundamental concept among philosophers, psychologists, activists, and others who think seriously about what motivates people to do good. It was introduced by historian William Lecky in the 1860s and popularized by philosopher Peter Singer in the 1980s.

Now it’s cropping up more often in activist circles as new social movements use it to make the case for granting rights to more and more entities. Animals. Nature. Robots. Should they all get rights similar to the ones you enjoy? For example, you have the right not to be unjustly imprisoned (liberty) and the right not to be experimented on (bodily integrity). Maybe animals should too.

If you’re tempted to dismiss that notion as absurd, ask yourself: How do you decide whether an entity deserves rights?

Many people think that sentience, the ability to feel sensations like pain and pleasure, is the deciding factor. If that’s the case, what degree of sentience is required to make the cut? Maybe you think we should secure legal rights for chimpanzees and elephants — as the Nonhuman Rights Project is aiming to do — but not for, say, shrimp.

Some people think sentience is the wrong litmus test; they argue we should include anything that’s alive or that supports living things. Maybe you think we should secure rights for natural ecosystems, as the Community Environmental Legal Defense Fund is doing. Lake Erie won legal personhood status in February, and recent years have seen rights granted to rivers and forests in New Zealand, India, and Colombia.

And then there are some who argue that even machines can be granted rights. What about a robot we may invent in the future that seems just as sentient as chimpanzees and elephants, despite being made of silicon? Maybe you think it would be wrong to discriminate on the basis of substrate, so we need the legal system to recognize robot rights, a theme Northern Illinois University media studies professor David Gunkel explores in his new book of that name.

The idea of expanding humanity’s moral circle raises knotty questions. What happens when different beings have competing needs? How do we decide whose rights take precedence?

These are questions that activists for the rights of animals, nature, and robots all grapple with as they use the idea of the moral circle to mount their arguments. They say there’s no reason to assume that once we’ve included all human beings, the circle has expanded as far as it should. They invite us to envision a possible future in which we’ve stretched our moral universe still further.

Many factors enabled the moral circle to expand in the past

“The circle of altruism has broadened from the family and tribe to the nation and race, and we are beginning to recognize that our obligations extend to all human beings. The process should not stop there,” Singer wrote in his 1981 book The Expanding Circle, adding that to stop at human beings would be arbitrary. “The only justifiable stopping place for the expansion of altruism is the point at which all whose welfare can be affected by our actions are included within the circle of altruism.”

Singer went on to argue that reason, by its nature, doesn’t tolerate inconsistency and arbitrariness — so if we follow the path of rational thinking, it’ll lead us to push past inherited biases, whether they’re against other people or other species. He believes rational thought has played a major role in expanding the moral circle over the centuries.

“Reason enables us to take the point of view of the universe,” he told me.

Although rationality might help nudge us toward a more universal perspective, it alone can’t get us all the way there. There are other psychological, sociological, and economic forces at work.

Psychologists have shown that we tend to feel more capable of extending moral concern to others if we’re not competing with them for scarce resources and if our own needs are already taken care of. Abraham Maslow famously illustrated this basic concept with his image of a pyramid representing our hierarchy of needs.

Maslow’s hierarchy of needs
Maslow’s hierarchy of needs.

It’s pretty hard to worry about the lofty goals at the top of the pyramid if we’re busy worrying about our own bodily safety, which is at the base.

Mapping this insight onto the moral circle, a team of Australian psychologists noted in a 2016 study: “One possibility is that moral expansiveness is evident in cases for which people’s basic needs have been met, allowing them to turn their attention and resources to more distant entities.”

Scholars have tried to show through particular historical examples how the development of new technologies can create the conditions for more people to gain rights. In some cases, that’s because the inventions take care of some of our more basic needs. Emanuela Cardia at the University of Montreal studied more than 3,000 censuses from the 1940s and found that household inventions — the washing machine, the refrigerator, the electric stove — were a major engine of liberation for women. Once the washing machine was invented and made widely accessible, for instance, women were freed up to do other things, like join the workforce.

Other technological innovations contributed to women’s liberation, not by nixing the need for them to labor so long at home but just by making it easier for them to leave home. The invention of the bicycle increased women’s mobility and independence so dramatically that Susan B. Anthony once said, “I think it has done more to emancipate women than anything else in the world.”

Similarly, other inventions have arguably catalyzed the expansion of the moral circle. Steven Pinker, in his book The Better Angels of Our Nature, says the printing press was crucial to humanity’s ethical development because it helped spread humanitarian ideas.

This isn’t to say we should adopt a technologically deterministic view. Tech innovation isn’t necessarily the primary factor allowing the moral circle to expand (and in fact, it can often cause a lot of harm). But it’s one of several factors that can make a larger moral circle more likely.

Another factor, of course, is the presence of activists who are willing to work damn hard to push the boundaries of the circle. Yes, the bicycle was important. So was Susan B. Anthony.

Strategies for proactively expanding the moral circle — for example, to include animals

Some activist movements have been more successful than others. So in trying to figure out how advocates can boost their chances of successfully expanding the circle, it makes sense to investigate what contributed to the success or failure of past movements.

One group taking that historical approach is the Sentience Institute, which bills itself as “an advocacy think tank researching and advising advocates on the most effective strategies to expand humanity’s moral circle.” In 2017, the institute chose the British anti-slavery movement as a case study and used it to identify successful tactics and best practices that can be applied to a very different context: today’s movement against animal farming.

Jacy Reese, the co-founder of the Sentience Institute and author of The End of Animal Farming, told me the study yielded a number of interesting insights. For one, he said, “Anti-slavery advocates were having the exact same debates that we’re having in the animal rights movement.”

One debate common to both movements is whether incremental reforms do more harm than good. Even as abolitionists campaigned for small reforms that they hoped would make life a bit easier for slaves, some worried that approach would lead people to think the problem had been solved and would cause complacency about ending slavery altogether. But that’s not what happened. “We’re finding evidence that there was more momentum than complacency,” Reese said.

To him, that suggests animal rights advocates should push ahead with cage-free campaigns and other incremental reforms, because they’re unlikely to cause too much complacency, at least if certain conditions are met.

Meanwhile, psychologists are conducting empirical research to understand what motivates people to expand the moral circle. They’ve found that a lot depends on how the issue is phrased.

In a 2009 study, the Australian psychologist Simon Laham found that if you ask people which entities they’d include in their circle, they produce a smaller circle than if you ask them which entities they’d exclude. “Clearly,” Laham writes, “if one wants to foster expansiveness of moral regard, one should focus not on why an entity should be afforded moral treatment, but why an entity should not be.”

In 2011, an international team of psychologists found that if you ask people to compare animals with humans, that yields a larger circle than if you ask them to compare humans with animals. Again, even though the exercise is basically the same, the way you package it matters.

Here’s another important lesson, gleaned from multiple psychology studies: We humans are much more likely to extend concern to entities we perceive to be like us. When we view animals as having cognitive and emotional capacities similar to humans’, we tend to include them in our moral circle, while animals that aren’t so easily anthropomorphized get left out. One 2015 study even found that “simply being asked to consider whether dogs have human-like traits can temporarily increase support for animal rights more broadly.”

For advocates, this could suggest that anthropomorphizing animals is a highly worthwhile strategy — when you can pull it off. It might not work so well with, say, chickens, so it doesn’t make sense to rely exclusively on this strategy if you want to reduce high-impact animal suffering. But it’s one useful tool in the arsenal, and you can already see it at work in the legal campaigns seeking personhood status for animals.

How to handle marginal cases like plants and robots

In 2016, psychologists asked participants to place various human and nonhuman entities within defined boundaries that indicate how much moral concern they deserve. They called this the moral expansiveness scale. Here’s how they described their findings:

People have a tendency to put their family and friends at the center of their moral circle, with other human groups afforded lower levels of priority. In-group members are more central than out-group members, followed by highly sentient animals, the environment, animals with low sentience, and plants. (Villains, interestingly, often lie outside people’s moral circles altogether.)

The experiment shows, in stark visual terms, that many people think sentience is a crucial factor in deciding how much moral concern an entity deserves. Humans are favored over chimps, chimps are favored over chickens, chickens are favored over plants. (Reflecting on why villains get kicked to last place despite being human, the researchers theorize that it might be because they’re perceived to have a high level of agency or moral responsibility, and yet they’ve violated it, so they deserve punishment.)

Moral Expansiveness Scale

Plants are an interesting marginal case. In recent years, some have argued that plants have some degree of sentience. They seek out certain outcomes (like sunlight) and avoid others, they send out biochemical distress signals to other plants, and they “seem to lose consciousness” when sedated in scientific experiments.

But the idea that plants are sentient is hotly contested — a status reflected by their outlying position in the moral expansiveness scale. Both Reese and Singer told me they don’t see plants as sentient, although they said they’d change their views if convincing new evidence were to emerge.

“Is there something that it’s ‘like’ to be a tree when that tree is being chopped down or not getting water and therefore dying? My guess is no,” Singer said.

For his part, Reese said, “We need more scientific knowledge before we can resolve the questions about how much we should care about plants.”

One marginal case not tested for in the moral expansiveness scale is artificial intelligence. For Singer, the question of whether future robots will belong in our circle is straightforward. “The rights of robots is still just a case of how you apply the boundary of sentience. If AI is sentient, then it’s definitely included, in my view. If not, then it’s not,” he told me.

How we’re going to discover whether a robot is sentient is still open for debate, but to Singer it’s obvious that whenever the answer turns out to be yes, inclusion in the moral circle must follow.

A critical perspective on the idea of the moral circle

It’s worth noting that any choice of litmus test for inclusion in the circle is, to some degree, culturally determined. Instead of working to empirically determine which entities are and aren’t sentient, you might sidestep that whole question and believe instead that anything that’s alive or that supports life is worthy of moral consideration.

That’s what Albert Schweitzer did when, inspired by the Indian religion of Jainism, he formulated his ethic of “reverence for life.” Here’s how he explained it:

A man is really ethical only when he obeys the constraint laid on him to help all life which he is able to succor, and when he goes out of his way to avoid injuring anything living. He does not ask how far this or that life deserves sympathy as valuable in itself, nor how far it is capable of feeling. To him life itself is sacred.

Jainism, which was founded in the sixth century BC, has long emphasized the supreme value of ahimsa, or nonviolence to all living creatures. Many monks take this so seriously that they cover their mouths with fabric to avoid accidentally breathing in insects, and sweep the ground ahead as they walk to avoid stepping on them.

In Latin America, the Quechua people of the Andes draw on the concept, rooted in indigenous spirituality, of sumak kawsay (also known by the Spanish name buen vivir), an understanding of the good life that entails living in harmony with the natural environment. In this paradigm, nature is not property with instrumental value — it’s inherently valuable and has its own inalienable rights. Nature’s rights to exist and flourish are even enshrined in Ecuador’s constitution.

Examples like these complicate the Western narrative of moral progress. The circle may have expanded to include more beings in more places over the centuries, but the expansion is by no means linear. For some, like the Jains and Quechua people, the inclusion of all animals and of nature in the circle has long been morally obvious. So when talking about expanding the moral circle, it’s worth taking care to avoid Eurocentrism, the concept of progress that views Western historical innovations as the only ones that count.

When I raised this critique with Singer, he said, “You’re right that when I talk about it as a linear process, I’m talking about broadly Western development. But I don’t think the fact that there are other cultures that take different views is in itself a reason to assume they are right and we are missing something. We need to ask why they reached their conclusions and whether there is something to be learned from them.”

That’s a fair point, and it brings up one last important observation. Although it may be tempting to think that the larger your moral circle is, the more it maps onto contemporary progressive ideals, that’s not necessarily right.

For example, when examining cases at the margins of life, one thing people ask is whether fetuses should be brought into our circle more centrally. Philosophers like Judith Jarvis Thomson as well as psychologists like Simon Laham have examined how our judgments about whether fetuses belong in the circle may inflect our positions on abortion. The moral calculus around that debate is notoriously fraught, not least because those who think fetuses deserve more moral concern still have to weigh that concern against a right that will be in competition with it: a woman’s right over her own body.

How wide will humanity’s moral circle be in 100 years? It’s entirely possible that we’ll have expanded it in some respects and narrowed it in others. I can imagine us having laws against eating sentient animals, even as we continue to repress certain classes of people. When we look at human history, we see not linear progress but a messy squiggle. Its contours are defined by who’s in power, as is the very definition of what counts as progress.

In The Expanding Circle, Singer notes that “today’s enlightened thinking often turns out to be tomorrow’s hidebound conservatism,” adding: “Perhaps my incomprehension proves only that I, like earlier humans, am unable to break through the limited vision of my own time.”

Because we are all products of our time, that intellectual humility is the healthiest posture we can adopt. Not having simple answers may make us uncomfortable, but I tend to think it’s a productive discomfort.

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