Theories of Moral Considerability: Who and What Matters Morally?

Author: Jonathan Spelman
Category: Ethics
Word count: 999

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There is widespread agreement that adult humans deserve moral consideration,[1] which is to say, roughly, that when deciding whether to perform an action, we should take its effects on adult humans into account.[2] 

But what else deserves moral consideration? Fetuses? Nonhuman animals? Plants? Ecosystems? Answering this question is important since it would help us answer ethical questions about abortion, animal testing, meat-eating, species management, and more.

Below, we survey five theories of moral considerability.[3] They all accept that adult humans deserve moral consideration, but they disagree about why that is. As a result, they disagree about what else deserves moral consideration.

Armed game wardens watch over an endangered northern white rhino at a nature conservancy in Kenya.
Armed game wardens watch over an endangered northern white rhino at a nature conservancy in Kenya.

1. Ratiocentrism

According to ratiocentrism, adult humans deserve moral consideration because they are rational (i.e., they act on reasons, not just on impulses or instincts).[4]

Ratiocentrism has the plausible implication that if rational space aliens exist, they also deserve moral consideration. At the same time, it has the implausible implication that neither infants nor people with severe mental disabilities deserve moral consideration (since they aren’t rational, i.e., they don’t act on reasons).

Ratiocentrists could respond to this worry by saying that what matters for moral considerability isn’t being rational but being potentially rational. On this view, infants and people with severe mental disabilities deserve moral consideration, not because of the capacities they have, but because of the capacities they could have. It is unclear, however, what it takes to be potentially rational.

2. Anthropocentrism

Another response to the worry described above is to adopt anthropocentrism, the view that adult humans deserve moral consideration simply because they are biologically human.

Since infants and people with severe mental disabilities are human, anthropocentrism can explain why they deserve moral consideration. But anthropocentrism also has a weakness; it seems to be speciesist.

What is speciesism?[5] Speciesism was first proposed as an analogue of racism or sexism.[6] Racism and sexism are problematic because they use morally irrelevant features (viz., race and sex) to justify treating certain individuals (e.g., black people and women) worse than others (e.g., white people and men). Analogously, speciesism involves using a seemingly morally irrelevant feature (viz., species membership) to justify treating certain individuals (e.g., nonhuman animals) worse than others (viz., humans).

Defending anthropocentrism against the charge of speciesism requires arguing either that species membership is morally relevant or that there is some other morally relevant feature that all and only humans have.

The first route isn’t particularly promising as evidenced by the fact that if we found out that some small percentage of the “human” population were actually rational space aliens disguised as humans, we wouldn’t infer from this that they didn’t matter morally.

Regarding the second route, there might be some morally relevant feature that all and only humans have; however, it’s hard to identify what that feature would be.[7]

3. Sentientism

A third view of moral considerability, sentientism, is the view that adult humans deserve moral consideration because they are sentient (i.e., have conscious experiences).[8]

Unlike ratiocentrism or anthropocentrism, sentientism is able to explain why it’s wrong to harm most nonhuman animals, even if they are unowned or unloved.[9] After all, kicking a stray dog seems to be wrong for the same reasons it’s wrong to kick people, namely, because kicking them is disrespectful and causes them pain.[10]

One criticism of sentientism is that it implies that some of our current practices (e.g., industrial animal agriculture and the use of animals in biomedical research) are deeply problematic. But maybe that’s right. Maybe those practices are deeply problematic.

4. Biocentrism

Some go even further and argue that all living organisms deserve moral consideration.[11] This view is biocentrism.

Biocentrism can explain some intuitions that other theories cannot. Imagine that you’re the last person on Earth. Would it be wrong for you to chop down the last redwood tree, just for fun?[12] Many people think it would be wrong for you to do this, and it’s easy for biocentrism to explain why, because your doing so would be bad for a living thing.

But biocentrism also has some implausible implications. For example, it seems to imply that it’s wrong to weed one’s flower beds. In response, biocentrists could argue that even though their theory entails that plants deserve moral consideration, it doesn’t entail that plants deserve the same kind or amount of moral consideration as humans.[13]

5. Ecocentrism

Finally, according to ecocentrism, what deserves moral consideration isn’t individual beings but collectives or groups, specifically those that promote the flourishing of ecosystems (e.g., wolf packs and aspen groves).

On ecocentrism, most individual plants and animals deserve moral consideration because they promote the flourishing of ecosystems. But not all individual plants and animals deserve moral consideration. Consider, for example, European rabbits, which were introduced into Australia in 1859.[14] Because they threatened the local ecosystem, ecocentrism entails that they didn’t deserve moral consideration and that Australians would have been justified in exterminating them.[15]

Some see this implication of ecocentrism as a strength, but others see it as a weakness. In fact, some of ecocentrism’s opponents have noted that given the environmental degradation caused by humans, ecocentrism seems to have the implausible implication that it would be morally permissible to kill off a large percentage of the human population.[16]

6. Conclusion

Theories of moral considerability can help us answer a variety of practical ethical questions, but they can’t answer those questions by themselves. For example, even if we knew that sentientism was true and, therefore, that nonhuman animals deserve moral consideration, we couldn’t know whether meat-eating was morally wrong without knowing whether nonhuman animals have rights or how to weigh their interests against the interests of the other things that deserve moral consideration.

In order to answer these practical ethical questions, then, we would have to figure out not only who or what deserves moral consideration but also how to treat the things that deserve moral consideration. This requires combining theories of moral considerability, ethical theories, and an understanding of who or what is being considered.


[1] Some philosophers talk about “moral consideration” using the equivalent or closely related concepts of “moral standing” or “moral status.”

The claim that all adult human beings deserve moral consideration has been denied throughout much (or most) of human history, but it is clear to us now that their reasons for doing so were not good ones. See, e.g., Dan Lowe’s Aristotle’s Defense of Slavery.

[2] In technical terms, to say that adult humans deserve moral consideration is to say that they have inherent value or that they matter for their own sake.

[3] In their strongest form, these theories purport to identify features that are necessary and sufficient for deserving moral consideration. However, these theories also come in weaker forms. So, whereas a strong version of anthropocentrism might say that being human is necessary and sufficient for deserving moral consideration, a weaker version might say simply that human beings deserve a special kind of moral consideration or a greater amount of it than other beings.

[4] Immanuel Kant (1724-1804) is a paradigmatic example of a ratiocentrist. See Deontology: Kantian Ethics by Andrew Chapman for an introduction to Kant’s ethics.

[5] For further discussion, see Speciesism by Dan Lowe.

[6] In “The Moral Status of Animals,” Lori Gruen (2017) notes that the word “speciesism” was first coined by Richard Ryder but then popularized by Peter Singer in his article “All Animals Are Equal” (1974) and subsequent book Animal Liberation (1975/2009).

[7] Give it a shot. Try to think of some feature that all and only humans have. My guess is that if all and only humans have the feature (e.g., human DNA), then it probably isn’t morally relevant. Alternatively, if it is morally relevant (e.g., intelligence), then it probably isn’t something that all and only humans have. To be clear, this doesn’t mean that humans aren’t special. It just means that even if humans are special, it doesn’t follow that they are the only things that deserve moral consideration.

[8] Jeremy Bentham, an early sentientist, famously expressed this view in An Introduction to the Principles of Morals and Legislation, writing, “The French have already discovered that the blackness of skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor. It may come one day to be recognized, that the number of 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. … The question is not, Can they reason? nor, Can they talk? but, Can they suffer?” (1789/1988: 311). See Daniel Weltman’s “Can They Suffer?”: Bentham on our Obligations to Animals

[9] I say “most” here because whether some animals (e.g., insects) are sentient is controversial, and others (e.g., bivalves) are widely thought not to be sentient.

[10] Tom Regan (1985) makes this sort of argument.

[11] Paul Taylor (2011) and Gary Varner (1998) advance versions of biocentrism.

[12] Richard Routley (1973) famously proposed a thought experiment along these lines.

[13] Biocentrists could, for example, draw a distinction between various kinds of interests and then argue that the satisfaction of certain kinds of interests (e.g., psychological interests) matters more than the satisfaction of other kinds of interests (e.g., biological interests).

[14] See “Rabbits introduced.”

[15] Aldo Leopold, probably the most well-known ecocentrist, famously wrote, “A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong if it tends otherwise” (2020: 211). Since exterminating European rabbits would have promoted the integrity, stability, and beauty of the local ecosystem, Leopold’s land ethic entails that exterminating them would have been not only morally permissible, but morally right.

[16] Ronald Sandler (2017: 261) raises this worry.


Bentham, Jeremy. An Introduction to the Principles of Morals and Legislation. Prometheus Books, 1789/1988.

Gruen, Lori. “The Moral Status of Animals.” The Stanford Encyclopedia of Philosophy (Fall 2017 Edition). Edited by Edward N. Zalta, 2017.  

Leopold, Aldo. A Sand County Almanac: And Sketches Here and There. Oxford University Press, 1948/2020.

“Rabbits introduced.” National Museum Australia. 13 August 2020.

Regan, Tom. “The Case for Animal Rights.” In Defense of Animals. Edited by Peter Singer, Basil Blackwell, 1985, pp. 13-26.

Routley, Richard. “Is There a Need for a New, an Environmental, Ethic?” Proceedings of the XVth World Congress of Philosophy 1, no. 6 (1973): 205-210.

Sandler, Ronald. Environmental Ethics: Theory in Practice. Oxford University Press, 2017.

Singer, Peter. “All Animals Are Equal.” Philosophical Exchange 5, no. 1 (1974): pp. 103-116.

Singer, Peter. Animal Liberation: The Definitive Classic of the Animal Movement (Updated Edition). Harper Perennial Modern Classics, 1975/2009.

Taylor, Paul. Respect for Nature: A Theory of Environmental Ethics. Princeton University Press, 1986/2011.

Varner, Gary. In Nature’s Interests? Interests, Animal Rights, and Environmental Ethics. Oxford University Press, 1998.

Related Essays

Applied Ethics by Chelsea Haramia

“Can They Suffer?”: Bentham on our Obligations to Animals by Daniel Weltman

Aristotle’s Defense of Slavery by Dan Lowe

Deontology: Kantian Ethics by Andrew Chapman

Consequentialism by Shane Gronholz

Speciesism by Dan Lowe

The Ethics of Abortion by Nathan Nobis

The Moral Status of Animals by Jason Wyckoff

Free Will and Moral Responsibility by Chelsea Haramia


Thanks to the editors of 1000-Word Philosophy for their helpful comments on earlier drafts

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About the Author

Jonathan Spelman is an assistant professor of philosophy at Ohio Northern University. He received his PhD in philosophy from the University of Colorado Boulder, and he specializes in ethics. When he’s not doing philosophy, he enjoys taking photos and spending time with his family. 

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