The naturalist worldview includes atheism, which is simply a lack of belief in a god or gods, because there is no good evidence for their existence. Atheism implies little about ethics—except to stipulate that ethical thinking shouldn’t be driven by a belief in deities or religions.

The use of evidence and reason goes beyond the scientific method as narrowly defined, but scientific thinking is at its core. The naturalist worldview (see The Brights ) rejects belief in the supernatural and mystical because there is no good evidence for their existence. If evidence of these types of phenomena were discovered, they would no longer be supernatural, and we could build factual knowledge about them.

We start with using evidence and reason as the basis of our beliefs – because reality is all there is. Fictional stories are real things too – as patterns of brain activity, states within computers or as ink on a page – but the subjects of those stories do not exist.

In this worldview, we must construct our own ethics: first, by granting moral consideration for all humans. We do so because we know directly, from our own experience, that we can both suffer and flourish—that is, that we can experience both qualitatively bad and good things. Science and our own experience show us that other humans experience suffering and flourishing largely as we do. We care about the experiences of other humans because of our evolved tendencies to cooperate and feel compassion, because of enlightened self-interest, and perhaps because we strive to take an impartial standpoint not bound to our own perspective. While many aspire to feel equal compassion for all humans, most of us prioritize some over others—but we grant at least some meaningful moral consideration to all. That leads us to humanism—a commitment to evidence, reason, and compassion for all humans.

Let’s take a further step… Sentientism

Sentientism is an ethical philosophy that, like humanism, rejects the supernatural and applies evidence and reason. However, it grants moral consideration to all sentient beings, not just humans. Sentience is the capacity to experience suffering and flourishing. Things that can’t experience might be important in other ways, but they don’t warrant our moral consideration. A mountain or a river is important only because of the effect it has on the experiences of sentient beings like us.

Sentientism goes further than humanism because humans aren’t the only sentient beings. Others deserve our moral consideration too. The most obvious are non-human animals. While scientific debate continues on the boundaries (sea sponges, for example, are animals with no brain or nervous system), it’s clear that most animals, particularly those we farm in their billions, are sentient. It’s sentience, not a somewhat arbitrary species boundary, that matters.

Eventually, we may also create or come across new types of sentient beings: general artificial intelligences or even alien species. It may seem fanciful, but surely our ethics should help us think about how we should treat them and how they should treat each other, even as we also worry about how they will treat us.

The diversity of sentient beings is already breathtaking and science indicates that, certainly between species, degrees of sentience vary substantially. The sentientist position, or at least my conception of it, allows us to grant different degrees of moral consideration depending on where on the sentience spectrum each being lies. This contrasts with the most extreme form of anti-speciesism, which can imply that all species (presumably only and all animal ones) deserve equal moral consideration. Mark Wright wrote an interesting Areo article on this type of absolutism here. Sentientism also avoids anthropomorphising animals. They are likely to experience differently from humans – but their ability to experience still warrants at least a base level of moral consideration.

If you’re a humanist atheist and a morally motivated vegan or vegetarian, you’re likely to be a sentientist. Although you may be unfamiliar with the term, the ethics will probably fit. However, the vast majority of people around the world disagree with sentientism in action, if not in belief. Many, while using evidence and reason daily, still grant the validity of supernatural or revealed knowledge. Others don’t grant moral consideration to animals and use products that require their suffering and death. Still others don’t grant proper moral consideration to sub-groups of humans, based on gender, sex, skin color, race, sexual orientation, disability, nation, tribe, or some other classification or boundary.

How can Sentientism help us?

Sentientism encapsulates the powerful benefits of humanism, already a critical philosophy and growing, global movement. Both are pro-human rights and focused on our common global humanity. Both are anti-sexist, anti-racist, anti-ageist, anti-nationalistic, anti-fascist and anti-LGBTQ+ phobic. Both humanism and sentientism help us focus on what we have in common—our humanity and our sentience. Identity politics can help identify problems and provide mutual support within groups. Humanism and sentientism can help us develop solutions that we can all identify with and work on together—given our shared reality and reasoning.

Like humanism, sentientism is pro-science, reason, and evidence and therefore against fabrication, fake news, unsubstantiated conspiracy theories, cultural relativism, and religious and supernatural thinking. All the problems and opportunities we face—from the existential threats of climate change, nuclear war, and biological or technological development (including AI) to the immediate challenges of global poverty, conflict prevention, development, and health—are better addressed with facts and critical thinking rather than dogma.

There are two areas in which sentientism goes further than humanism. For many, animal welfare is a critical issue in its own right, given the more than 100 billion animals we kill each year for food, drink, and other animal products. Transitioning away from animal farming is also an important step toward reducing our negative impact on the environment in terms of land, water, and energy use; emissions; and pollution. While many humanists already grant moral consideration to non-human animals (for example, the national organization Humanists UK includes this in its definition of humanism), sentientism makes that explicit, as it views causing the suffering and death of sentient animals as ethically wrong.

Sentientism also helps us think through and prepare for the implications of general artificial intelligence (GAI). We need to crystallise and evolve our own ethics to help us direct or align the ethics of AIs safely – the concepts of sentience, evidence and reason help to do that. We also need to think carefully about the rights and moral consideration we might need to grant to AIs themselves if or when they attain and then increase in sentience.

Sentientism as a movement?

Sentientism has remained a fairly niche term since it was developed as a concept by philosophers including Richard D Ryder and Peter Singer in the 1970s. Since then, we have seen important yet separate developments in veganism, vegetarianism and animal rights on the one hand and in the “Rise of the none’s”, atheism and humanism on the other. These movements now have a plethora of international and local organisations building communities, driving activism and conducting lobbying– but there is little that brings the two threads together or underpins them. I would like to see sentientism play that role.

There is already an untapped synergy between these movements. In a recent show-of-hands poll of an audience of around a thousand U.K. humanists, approximately 40 percent said they were vegan or vegetarian—a rate much higher than that of the general population. It also appears, again anecdotally, that moral vegans and vegetarians are more likely to be atheists or humanists than the general population. To me, that’s because evidence and reason underlie both viewpoints.

A range of other developments and movements also hint at a latent sentientist philosophy. Environmental and ethical concerns are driving more people to think about the animal suffering we cause and the damage to the planet occasioned by animal farming. The development of artificial intelligence is stimulating new fields of thought about robot rights. People are starting to recognize the limitations of identity politics in improving social cohesion and community building. The Effective Altruism movement is using evidence and reason to find out how we can do the most good for all sentient life.

Maybe it’s time for us to pick up on these hints and upgrade humanism to sentientism. Rather than remaining as a niche philosophy, it could build on humanism’s momentum as an inclusive, well-grounded, potentially unifying movement for addressing the world’s problems and opportunities.

Human culture has enormous inertia and our traditional, in/out group and religious memes run deep. However, our ways of thinking are, fortunately, relentlessly shaped by reality. That influence has already helped us progress rapidly over the decades and centuries. Evidence and reason-based thinking proves its worth every day—there is no viable alternative to slowly, skeptically becoming less wrong by observing reality and testing our thinking against it.

Reason and facts are also helping us to build a stronger foundation for our ethics. We are coming to understand more about sentient minds, what our experiences have in common with others, and how we can reduce suffering and flourish.

While in/out group thinking can seem to work for the in-group in the short term, we’re all learning, sometimes painfully, that we do better as our circles of concern expand and as we cooperate ever more widely—ultimately, with all sentient beings.

That’s why I’m optimistic. The truth will win through eventually, and sentientism, at its core, is a recognition of the truth.