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I interviewed Peter Singer, Jamie Woodhouse and Luke Hecht to explore sentientism and the expanding moral circle.

After months of waiting there’s finally a new A Happier World video! This one took a really long time to make. The interviews are from June 2022! Glad it’s finally out. In the next months I’ll definitely make videos that are a lot shorter so there’s no need to wait as long anymore.

Would love to hear what you think!

Thanks to Adrian Nelson and Euan Mclean for helping with the script, and all the others who’ve provided valuable feedback.

Charities mentioned

The Good Food Institute 
The Humane League 
Wild Animal Initiative

Things I mentioned in the video

The Expanding Circle by Peter Singer 
Animal Liberation (Now) by Peter Singer 


Al Ma’arri poems

Research on the sentience of insects, mussels, plants… 
https://www.animal-ethics.org/an-illustrated-physiology-of-nervous-systems-in-invertebrates/ https://forum.effectivealtruism.org/s/y5n47MfgrKvTLE3pw/p/tnSg6o7crcHFLc395 

Faunalytics study


Heroes of the past

Throughout history there have always been those who rejected the moral norms of their time, and bravely fought for progress.

In the 11th century for example, you had the Arab poet and philosopher Al-Ma'arri.

Blind from childhood, due to contracting smallpox at the age of 4, he nonetheless became one of the greatest classical Arab poets. During his life he refused to sell his poems and lived in relative poverty. 

Al-Ma'arri famously rejected all forms of religious and superstitious thinking, instead arguing that reason should be the source of truth and revelation. 

This reasoning led him to reject all forms of violence, including against animals, which is why he decided to eat a diet only consisting of plants.

Another example of an individual who stood radically against the moral norms of their time was the 18th century philosopher, Mary Wollstonecraft. 

Today she’s remembered as one of the first feminist philosophers and the mother of Mary Shelley who wrote Frankenstein. But she also played an important role in the history of animal rights.

In the late 18th century, she published A Vindication of the Rights of Woman, that argued that women and men should be treated equally on account of women's capacity for consciousness and rational thought.

This triggered the translator Thomas Taylor to respond with a satirical paper titled A Vindication of the Rights of Brutes. This satirical piece stated: If having consciousness grants you rights, might as well give rights to animals! I'm not sure he was aware that Mary Wollstonecraft was an advocate for animal welfare as well.

Today, Taylor's satire doesn’t seem that absurd anymore. The Rights of Brutes was an accidental precursor to today’s thriving animal welfare movement. 20th century philosophers like Tom Regan and Peter Singer have used some of the same kind of basic arguments in their writing.

The Expanding Circle

The ethics of many societies has changed dramatically over the past centuries: 200 years ago slavery was still widely practiced throughout the Western world; about a century ago women got the right to vote in many western countries; homosexuality was only made legal nationwide in the UK in 1982. The world’s current most free, democratic and egalitarian places have a dark past. While there is still significant room for progress, it’s easy to overlook how far we have come since the past.

One way to think about moral progress is the concept of the expanding moral circle.

The idea can be traced back to Irish historian William Lecky, who argued in 1869 that our ethical progress can be conceived as our moral circle expanding over time. 

That is, the group of things or beings we give moral consideration to. In Lecky’s view, our once very local morality gradually expanded to include larger and larger groups. From the family, to the local community, to nations, from all members of a race, to all races, and eventually to all humanity.

But will our moral circle continue expanding? And if it does, where might it eventually lead us?

People have proposed adding animals, insects, plants, robots, or even ecosystems. So where do we draw the line?

Travel vlog!

One philosopher who has thought a lot about these questions is Peter Singer. So I decided to interview him about his views. He was giving a talk in London, and since I live in nearby Brussels, I thought it would be a great opportunity to meet him.

Singer is the author of several highly influential books including, The Expanding Circle, and Animal Liberation, in which he argues that our moral obligations ultimately extend to all sentient life.

Why sentience?

Peter Singer: The view that I take about the basis for expanding the moral circle is that we should consider all beings who are capable of experiencing pleasure or pain, at a minimum, some kind of consciousness in other words.

The idea that consciousness or sentience should be the core requirement for inclusion into our moral circle is an idea that is growing more popular with philosophers and thinkers. One such thinker is Jamie Woodhouse. He uses the term “sentientism” to describe the growing secular movement towards this view. It’s derived from the word “sentience”, here defined as the capacity to feel pleasure and pain. I also talked with him during my trip to London.

Jamie Woodhouse: So where humanism is committed to universal compassion for all humans, regardless of sex, race, gender, ethnicity, any other characteristic, every human matters, sentientism challenges that. Why should it just be humans? All sentient beings should matter.

So what’s the case for sentientism?

Why should we put the capacity to feel pain or pleasure at the center of our morality?

Peter Singer: Why is it that sentience really matters? I think the best answer to that is by thinking about our own attitude to pain and pleasure. If we think about a pain in particular that we're not experiencing because of any later benefit, so it's not like a dentist drilling our tooth because otherwise we'll have a worse toothache, but it's just that we're experiencing pain and nothing positive will come of it. Then I think it's really obvious to all of us that we would be better off without that experience. That is, experiencing something which means that our life has gone less well than it would have. So I think it's one of the few cases where we can say that there's something that is self-evidently bad. And conversely when we think about a really pleasurable experience or about being really happy about something we can say that that is self-evidently intrinsically good.

Sentientism says we should give moral value to all sentient creatures. This will come naturally to many people. After all, we don’t want to discriminate based on gender or race, so why discriminate based on species?

The philosopher John Rawls found an intuitive way to explain this using a thought experiment that is now known as the veil of ignorance.

Imagine that you are behind a veil of ignorance that prevents you from knowing your own race, your gender, your place in society, or even your species. You’re then asked: which beings should be given rights? Who do we want to treat with respect, and who can be hunted and killed for food? From this point of view, you may be hesitant to suggest that a certain group should be left out of the moral circle. Because when the veil is lifted, you might just find yourself in that very group.

Jamie Woodhouse: Rawl's veil of ignorance, I think, is a really interesting thought experiment because it forces us to take this sort of view from nowhere, a more neutral, fairer, less partial stance.

If you imagined a world where you could be injected into it as any other human or any other species, you design that world in a very different way

People often use other measures of moral significance, like intelligence or the capacity for language. But sentientists argue we shouldn't pay attention to these. In the 18th century, the philosopher Jeremy Bentham argued against these ways of measuring moral significance.

Peter Singer: Jeremy Bentham, writing at the time of the French Revolution, raised the question in a footnote about what is it that is supposed to draw the line between those who have a moral status and those who do not. "The French at that time have discovered that the color of a man's skin is no reason for abandoning him to the caprice of a tormentor". He was talking about French abolition of slavery at that time. And he then adds the remarkable and very forward-looking remark that perhaps one day the time will come when people will discover that whether you have fur or not or whether you have a tail is also not a relevant ground for deciding whether you have the moral status that entitles you to protection. "What else is it that could draw this line? Is it the ability to reason or to talk? A horse or a dog is beyond comparison, more rational and has more capacity to talk than a human infant of a day or a week or even a month old". So he's essentially saying that if we use reason or the ability to use language as the bounds of our moral concern, we would have to stop showing moral concern for infants. He's obviously assuming that's not what we're going to do so therefore, we should be extending this to all beings. "The question is not can they reason, nor can they talk, but can they suffer?"


Bentham is the father of utilitarianism, the moral view that the right thing to do is to take actions that will maximize the total amount of happiness or wellbeing and minimize the total amount of suffering in the world.

Decades and even centuries before these issues were widely accepted, Bentham and other utilitarians were passionate early advocates of women’s rights, the abolition of slavery, and the decriminalization of homosexuality. 

While most previous moral views only care about human wellbeing, utilitarians pushed those boundaries further to include all sentient beings. 

Today, utilitarianism remains an influential theory and continues to be defended by well-known thinkers like Peter Singer.

Utilitarianism and sentientism are related but distinct. Both claim that all sentient beings matter, but utilitarianism goes further in that it also tells you how to act. Sentientism doesn’t commit you to any moral view so it's compatible with many of them.

Jamie Woodhouse: So there are so many different ways of thinking about ethics. There are consequentialist approaches and utilitarian approaches. There are deontological approaches. There are feminist care ethics. There are relational approaches. There's a whole range of fascinating, different approaches to ethics. But I think the most important question is who gets to count in our ethical considerations, whichever system we use. So that's what sentientism focuses on. It doesn't tell you whether you should be utilitarian or deontological or use a care ethic. It says the most important thing is that we set the boundary of our moral scope so that all sentient beings get to count. And then we can fight over the right combination of ethics.

Not a new idea

The ideas behind sentientism are not new, in fact they’ve been expressed by thinkers for centuries and throughout multiple cultures.

Jamie Woodhouse: There are so many ideas from the deep past that resonate with sentientism. In a sense, it's not really a new idea at all. It's a new word. The ideas aren't new. So the word's only been around since the 1970s and eighties. But the idea of caring about non-human sentient beings has ancient, deep roots in many different cultures. So one classic example you look at is the idea of ahimsa, which is central to many of the Eastern religions. In essence, that means there is an imperative to do no harm. Which almost by definition, means we should have a concern for all beings that have the capacity to be harmed, i.e., are sentient.

Peter Singer: It's not simply a Western idea that pain is bad and that pleasure is good. You find it in Buddhism, for example, which has a precept of compassion for all living things and it talks a lot about suffering and about avoiding the infliction of suffering.

The early Chinese philosopher Mozi talked about suffering and pain and pleasure. I think it would be hard to find a tradition which actually did not regard pain as a bad thing. It might still practice the infliction of pain in some cases, perhaps to strengthen character, to show that you can go through hardship, to prove your manhood in some way.

But if you're simply talking about the infliction of pain for its own sake, I think you find that people everywhere will avoid that.

Let's go back to Al-Ma'arri, the Arab poet that I talked about earlier. He, too, can be thought of as a sentientist. His reasoning about the moral importance of sentience led him to reject the status quo and push for the expansion of the moral circle. 

In one of his poems he states:

“Do not unjustly eat fish the water has given up,

And do not desire as food the flesh of slaughtered animals,

Or the white milk of mothers who intended to nourish

their young, not noble ladies.

And do not grieve the unsuspecting birds by taking eggs;

for injustice is the worst of crimes.”

Does an insect feel pain?

There’s an obvious question that might be on your mind, that sentientism needs an answer to. How do we know which beings are sentient and which ones are not? Sure, a dog is probably sentient, but what about an ant? Or bacteria? Where do we draw the line?

This has proven to be a difficult question for scientists and philosophers, and yet it seems increasingly likely that millions of the other species with which we share the world are sentient. That is, they have the capacity to suffer. Many researchers are convinced that most animals with a nervous system are to some degree of sentient. This includes insects, though they likely don’t feel as much as say a cow or a chicken.

What about the rest of life? Some simpler forms of animals, like say mussels or oysters, might not feel any pain at all. And plants are extremely unlikely to feel anything.

It therefore seems that sentientism can be informed by philosophical and scientific progress.

What you can do

So now we know the theory behind sentientism. But what does it say about how we should act in practice? What does a good sentientist look like?

The most obvious way to help non-human animals is to eat less of them. The ideal would be to go completely vegan, but cutting down is better than nothing. 

You can try to avoid animal products that cause the most suffering. A study by Faunalytics found the most suffering-intensive products were chicken, fish and eggs.

You could also donate to effective animal charities or devote your career and time to helping farmed animals. We talk more about this in our video “How To Help Farmed Animals”.

Some argue that insect farming would make a great alternative to the farming of cows, pigs and chicken. But I wouldn’t be so sure of that. Insects may have at least some rudimentary capability to feel pleasure or pain, even if it’s not like us or other animals. And since insects are so tiny, it means that we have to consume a lot more insects per calorie than say a cow or a pig.

Wild animals

We’ve talked a bit about farmed animals, but what about wild animals? 

I discussed the wellbeing of wild animals with Luke Hecht, a researcher at Wild Animal Initiative, a non-profit organization that tries to figure out ways to improve the lives of wild animals.

Luke Hecht: So the main reason we focus on wild animals is the sheer number of wild animals. And also because a lack of attention on wild animals. I feel like it's sort of a next frontier for our moral circle expansion, to be taking responsibility for the welfare of animals, even if we haven't necessarily caused the problems they're facing. Humans cause a lot of suffering to wild animals, but wild animals also have a lot of challenges that humans have nothing to do with, like diseases and predation and starvation. There might be things that we could do to prevent them. 

Adult bears have pretty high survival rates. But even for an animal as formidable as a bear, if you were born as a bear, you have like 50% chance of making it through your first year as a cub.

The animal kingdom is full of fear, hunger, diseases and death. But most don’t consider this a pressing moral issue because that suffering is not caused by us. Sentientists believe that not only human caused suffering is important, but all suffering. The real question is: do we have the power to prevent it?

Luke Hecht: To people who say that messing with nature would cause more problems. I understand their fear. I think at Wild Animal Initiative, we are extremely cautious. Like we are thinking so much about indirect effects of everything and have so little confidence in recommending specific interventions. And I think that's healthy, while also recognising the sort of moral urgency of the issue. Humans are already intervening in nature on a massive scale, and we mostly just aren't really thinking about the consequences of our actions for wild animals. So while I think we need to be really careful not to do more harm than good, intervening in nature is not at all unprecedented. And I think that we can only really improve from where we are now. 

There are also some other unintuitive conclusions that sentientism might lead us to. One is the concern for people far away of us whether that means in space or in time. Peter Singer famously argued that our distance in space has no bearing on our ethical responsibility. 

Peter Singer: Nobody would say just because you live far away, you're not part of the moral circle. But if we ask not what do people say, but what do people do and how they act when there’s an emergency far away from us, or even in the absence of any particular emergency, if we just know that there are people in extreme poverty and that there are people dying because of that, then we find that there is a kind of a discount for distance. People are much less likely to act to help people who are far away or people who are different from them in terms of their ethnicity or the color of their skin. So we don't say that they're not part of the moral circle, but we act as if they are less significant. And I think that's quite wrong.

The question should not be “How far away are we from suffering?”, but “What can we do about it?”

Singer also argues that time should not be a factor of moral consideration.

Peter Singer: I think we should be impartial about time. So I don’t think we should discount the future. The only kind of discounting that I would accept is discounting for uncertainty. If we can prevent harm to somebody who is not alive now, but will be alive, whether they will be alive in 20 years or 50 years or 100 years or even a thousand years, we should try to prevent that harm. The question is how confident can we be that there will be people in 2000 years and how confident can we be that something that we're doing will prevent harm to them?

It can seem a lot harder to help future people as it’s hard to imagine how our actions today can help future generations. But there are some pretty clear ways you can help make the future more likely to go well.

Peter Singer: The fact that we should not discount the future is, of course, a reason for being particularly concerned about climate change, because that seems likely to have very adverse consequences for both people and non-human animals in future.

We live in a time of existential uncertainty – where humanity has acquired the wisdom to destroy ourselves, but not the wisdom to ensure that we don’t.

If humanity goes extinct that means that trillions of future people never get the chance to exist. So how we respond to existential risks today has a huge influence on the lives of future people and is therefore hugely important. 

We made an entire video on this topic that I recommend watching if you're interested. 

Aliens and robots

But all this talk about future people reminds me that there is another potential group of sentient beings we haven’t talked about yet: artificial sentient beings.

Could we ever create something that has the capacity to feel?

Peter Singer: You could ask a similar question about real robots, that is, about artificial intelligence, which possibly one day will produce conscious machines. I don't think we have achieved that yet and it may be several decades before we do. But if we are at some point convinced that we have produced consciousness in a machine, then we will have to give that being moral status. So yes, ultimately the moral circle might be expanded to include conscious machines.

Philosophers and scientists disagree about whether artificial intelligences will ever have the capacity to feel, but what if they do?

We’re definitely going to make more videos on the subject of artificial intelligence, so subscribe to don’t miss out!

And what about aliens? We don’t yet know if life exists elsewhere in the universe. Sentient extraterrestrials may exist elsewhere in our galaxy or beyond. If we ever discover such beings, it would seem that they too should be included within our moral circle.


The concept of the expanding moral circle is a powerful idea. It can help us to understand the historical development of our moral values as well as influence where we might eventually be heading. It offers an approach to moral reasoning that goes beyond human prejudices and biases. Sentientism proposes we should include at least all beings with a capacity to suffer in our moral circle. What do you think, are you convinced by the arguments for sentientism? Or do you think we should draw the line elsewhere?

If you liked this video or you think it’s important, share it with your friends!

We’ve tried our best to explain the topics in this video as accurately as possible. But since we’re human, there’s a good chance we’ve made mistakes. If you noticed any or if there’s something you disagree with, let us know in the comments down below. Thanks for watching!





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