Animal Liberation Now releases today! I received an advance copy for review, so will share some thoughts and highlights. (It feels a bit presumptuous to “review” such a classic text—obviously you should read it, no-one needs to await my verdict in order to know that—but hopefully there’s still some value in my sharing a few thoughts and highlights that stood out to me.)

Animal Liberation Now

As Singer notes in his publication announcement, he considers it “a new book, rather than just a revision, because so much of the material in the book is new.” I’m embarrassed to admit that I never actually got around to reading the original Animal Liberation (aside from the classic first chapter, widely anthologized as ‘All Animals are Equal’, and commonly taught in intro ethics classes).[1] So I can’t speak to any differences, except to note that the present book is very much “up to date”, focusing on describing the current state of animal experimentation and agriculture, and (in the final chapter) engaging with recent philosophical defenses of speciesism.

Empirical Details

This book is not exactly an enjoyable read. It describes, clearly and dispassionately, humanity’s abusive treatment of other animals. It’s harrowing stuff. To give just one example, consider our treatment of broiler chickens: they have been bred to grow so large they cannot support themselves or walk without pain (p. 118):

The birds may try to avoid the pain by sitting down, but they have nothing to sit on except the ammonia-laden litter, which, as we saw earlier, is so corrosive that it can burn their bodies. Their situation has been likened to that of someone with arthritic leg joints who is forced to stand up all day. [Prof.] Webster has described modern intensive chicken production as “in both magnitude and severity, the single most severe, systematic example of man’s inhumanity to another sentient animal.”

Their parents—breeder birds—are instead starved to keep their weight at a level that allows mating to occur, and for the birds to survive longer—albeit in a state of hunger-induced aggression and desperation. In short, we’ve bred these birds to be physically incapable of living happy, healthy lives. It’s abominable.

Our treatment of dairy cows is also heartbreaking:

Dairy producers must ensure that their cows become pregnant every year, for otherwise their milk will dry up. Their babies are taken from them at birth, an experience that is as painful for the mother as it is terrifying for the calf. The mother often makes her feelings plain by constant calling and bellowing for her calf—and this may continue for several days after her infant calf is taken away. Some female calves will be reared on milk substitutes to become replacements of dairy cows when they reach the age, at around two years, when they can produce milk. Some others will be sold at between one to two weeks of age to be reared for beef in fattening pens or feedlots. The remainder will be sold to veal producers. (p. 155)

A glimmer of hope is offered in the story of niche dairy farms that produce milk “without separating the calves from their mothers or killing a single calf.” (p. 157) The resulting milk is more expensive, since the process is no longer “optimized” purely for production. But I’d certainly be willing to pay more to support a less evil (maybe even positively good!) treatment of farm animals. I dearly hope these products become more widespread.

The book also relates encouraging legislation, especially in the EU and New Zealand, constraining the mistreatment of animals in various respects. The U.S. is more disheartening for the most part, but here’s one (slightly) positive note (p. 282):

In the U.S. the joint impact of the changes in state legislation and the campaigns to persuade corporations to change their purchasing policies has increased the proportion of hens not in cages from only 3 percent in 2005 to 35 percent in 2022, and that should continue to increase as more corporations meet their commitments.

(On the other hand, remember that cage-free hens may be living with thousands of other hens in the ammonia-filled air of a crowded shed, never able to go outside in fresh air and sunshine. It’s better than cages, but still a long way from free range or pasture-raised hens.)

Singer concludes:

Yes, there are more vegetarians and vegans than there were in 1975, and some of the reforms mentioned in this chapter have improved the lives of hundreds of millions of animals. On the other hand, there are now more animals suffering in laboratories and factory farms than ever before. We need much more radical changes than we have seen so far. (p. 284)

What is to be done?

Singer recommends veganism, or at least taking care to avoid purchasing factory-farmed meat. In a helpfully pragmatic section comparing the relative moral risk of different kinds of meat, Singer explains:

A study by the Sentience Institute estimated that in the United States, over 99.9 percent of chickens raised for meat are kept in factory farms, 99.8 percent of turkeys, 98.3 percent of pigs, 98.2 percent of egg-laying hens, and 70.4 percent of cows.… At the present time fewer than 1 percent of sheep are kept intensively, so lamb and mutton are unlikely to be from factory farms.

So, for those of us who aren’t (yet) strictly vegetarian, lamb may be the way to go. Beef is a gamble (I’m hoping the roast beef at Whole Foods is okay?), and for goodness’ sake, avoid chicken like the plague. Stick to “pasture raised” eggs. I wish we had more guidance on finding humane milk options; maybe all of the readily-available ones involve calf separation, but are some common brands (e.g. Organic Valley?) at least less harmful than others?

In any case, legislation seems more promising than individual consumption choices for achieving significant change here. (California’s proposition 12 being an encouraging recent example.) Perhaps the most important practical upshot of Animal Liberation Now is that we should all support animal welfare legislation to vastly improve conditions for animals on factory farms. Yes, this will make animal products more expensive. That’s the cost of reduced torture.

It’s just not possible, given current levels of demand, for meat to be both cheap and humane. Maybe cultured meat or other technological breakthroughs could eventually change this. But failing that, I think the morally best outcome would be for meat to become a luxury good, as would follow from the abolition of intensive (“factory”) farming.

I haven’t discussed animal experimentation yet. That chapter was also harrowing (including details of researchers deliberately traumatizing animals in hopes of inducing mental illness to study). Of course, Singer isn’t an absolutist about this:

If it really were possible to prevent harm to many by an experiment that involves inflicting a similar harm on just one, and there was no other way the harm to many could be prevented, it would be right to conduct the experiment. (p. 98)

But I wonder about the “no other way” clause here. A pertinent feature of non-human animals is that they cannot consent to harm. People can. Not that I think consent is morally magical, but it is a very useful tool for preventing mistreatment. If the benefits of research outweigh the costs, it should (in principle) be possible to sufficiently compensate participants for the harms they’re exposed to. Animals can’t tell us how much compensation would be necessary to make it worth it for them. People can. So the “other way” to go here would be to pay volunteers whatever it takes to convince them to consent. (Many medical ethicists hate this idea, but it is surely more ethical than experimenting on non-consenting beings without compensation.)

There’s obviously much more to be said here, especially when the risks are potentially lethal. But substituting compensated people in place of unconsenting animals strikes me as a possible way forward that was underexplored in this book. (Though Singer did flag that we should be more willing to experiment on human volunteers.)


Much of the book is indisputable in its criticisms of existing practices. Any reasonable moral view is going to entail that factory farming—effectively torturing animals just to make their products cheaper—is a moral abomination. While immensely practically important, such observations aren’t so philosophically interesting. What is philosophically interesting (and hence not strictly essential to the core practical upshot of the book) is Singer’s famous opposition to speciesism—giving less weight to an individual’s interests (e.g. in not suffering) simply because of the species to which they belong. The first chapter of ALN introduces and clarifies the equal consideration of interests principle (p. 4):

Precisely what our concern requires us to do may vary according to the characteristics of those affected by what we do: Concern for the well-being of children requires that we teach them to read; concern for the well-being of pigs may require no more than that we leave them with other pigs in a place where there is adequate food and room to roam freely. The basic element is taking into consideration the interests of the being, whatever those interests may be, and this consideration must, according to the principle of equality, be extended equally to all beings with interests irrespective of their race, sex, or species.

It is on this basis that the cases against racism and sexism must ultimately rest; and it is in accordance with this principle that speciesism must also be condemned.

Importantly, anti-speciesism is compatible with valuing typical human lives more highly than (say) chicken lives:

The evil of pain is, in itself, unaffected by the other characteristics of the being who feels the pain; while the value of life and the wrongness of killing may be affected by these other characteristics. To take the life of a being who has been hoping, planning, and working for some future goal is to deprive that being of the fulfillment of all those efforts; to take the life of a being with a mental capacity below the level needed to grasp that one is a being with a future—much less make plans for the future—cannot involve this particular kind of loss. (p. 27)

Despite these accommodations with common sense, anti-speciesism remains controversial when applied to the severely cognitively disabled. Many want to claim that all humans have “greater moral status” than non-human animals, even when the individual in question lacks the cognitive capacities typically appealed to in attempts to justify granting humanity such special status. Singer sees this as a mere bias. But it’s hard to shake the feeling that farming cognitively disabled humans would be even worse than farming pigs.

I wonder if the best defense of humanism[2] here would be on multi-level utilitarian grounds. Even if it’s true in principle that sufficiently cognitively disabled humans have similar moral status to (cognitively comparable) non-human animals, it may be that the best practical morality for us to inculcate is one that is more protective of all humans (or all beings of a rational species—we’re not discriminating against Martians here). Compare: in principle, it would be a good thing to farm short-lived happy humans (perhaps for their organs) who would otherwise not get to exist at all. But we find the idea repugnant, and that’s probably also a good thing. It causes us to lose out on some life-saving organs, and the value of the farmed lives themselves; but it may also prevent us from committing worse atrocities against each other.

Another unaddressed challenge to Singer’s view is that the very notion of a “disability” rests on kind-specific norms. It seems tragic for a human to be stuck with the cognitive capacities of a chicken—we feel that they’ve been deprived of capacities that they ought to have had. By contrast, it isn’t tragic for a chicken to have the cognitive capacity of a chicken. If we possess a magic pill that would provide typical human intelligence to either individual, it seems we have stronger reason to give it to the cognitively disabled human than to the chicken (bracketing extrinsic factors, like how others would react). If this judgment is “speciesist”, then maybe speciesism isn’t necessarily unreasonable? Alternatively, if we are to truly give up on assigning any moral significance to species, we may be committed to greater conceptual revisions than we’d realized. We may also need to give up on the distinction between treatment (of disability) and enhancement, for example.

Other philosophers have tried to defend speciesism in ways that Singer aptly addresses in the final chapter. For example, he notes (p. 272) that Kagan’s modal personism wrongly distinguishes between two equally capable human individuals on the basis of irrelevant details about the causes of their disability (i.e. whether genetic or accidental). And against Bernard Williams’ defense of ‘The Human Prejudice’ (in which Williams imagines asking, “Which side are you on?”, in the face of an alien invasion), Singer responds:

“Which side are you on?” appeals to some of our worst instincts. Wherever there is racial or ethnic violence, and a member of the dominant group that is inflicting the violence tries to dissuade their fellow Whites, Nazis, or Hutus from attacking Blacks, Jews, or Tutsis, that question will be asked. If it is, “I am one of you, and therefore I am on your side” is precisely the wrong way of answering it. That answer abandons the attempt to solve problems in the light of justice and reason, leaving the resolution of the disagreement to force. (pp. 270-71)


Animal Liberation Now is a vitally important book—living up to the reputation of the original, while updating its discussion to match the current state of the world. Humanity’s treatment of non-human animals may be the gravest ongoing moral disaster of our times, and I know of no other work that so clearly brings this fact to light.

For those who wish to support the book, ordering it within the first week of publication can help it to get on bestseller lists. Booking tickets to Singer’s speaking tour could also help spark media interest. (Use code SINGER50 for 50% off if you wish, or pay full price knowing that all profits will be donated to effective charities opposing intensive animal production.)

[Disclosure: Singer was one of my professors at Princeton, and I continue to regard him as a mentor. More recently, we’ve co-authored work together on pandemic ethics. So I’m admittedly personally biased to think well of him & his work. Of course, in light of the objective reasons, I’m inclined to think my bias entirely redundant!]

  1. ^

    Incidentally, I’m planning to write a Study Guide on the first chapter, soon!

  2. ^

    Though it’s also very possible that the same reasoning should lead us to extend rights to non-human animals, too—as Jeff Sebo argues here.


Sorted by Click to highlight new comments since: Today at 7:59 PM

I think it’s interesting that Singer advocates for veganism despite being a utilitarian, when protests, donations and careers focused on ending factory farming might be more effective, and veganism seems like a very “deontological solution” to farmed animal suffering.

Yeah, it is interesting. He actually begins chapter 4 ('Living Without Speciesism') with a section on "Effective Altruism for Animals" which talks more about protests, donations, and careers. But then goes on (in the subsequent, 'Eating Ethically', section):

All of the actions just mentioned are important things to do, but there is one more step we can take that underpins, makes consistent, and gives meaning to all our other activities on behalf of animals: We can take responsibility for our own lives, and make them as free of cruelty as we can. We can, as far as is reasonable and practical in our individual circumstances, stop buying and consuming meat and other animal products.

Which does sound very deontological!  (Maybe partly strategic, if more people are likely to be willing to change their diet as a first step? But I also get the sense that he just thinks it's deeply unreasonable for many of us to eat [factory-farmed] meat.  As an akratic omnivore myself, I kinda feel like he's... not wrong there.)

To be clear, I think veganism is good and worth advocating for, but I agree with you that I'd kind of expect the other (more?) "important things to do" to get comparatively more attention/priority, from a utilitarian perspective.

Has Singer ever made a "strategic utilitarian" case that going vegan provides a signal to others that you take the issue of animal suffering so seriously that you will make major changes to your life, and that this is a form of witness (akin to Christian religious witness) that both exposes others to and confronts them with that same issue in order to encourage them to take it seriously too? On a personal level that seems like a good strategy given our limited leverage as individuals on the industry, inasmuch as you are living according to your principles as well as having a broader impact by spreading those principles, and can also continue to campaign more directly against the industry.

Yes agree that there is an essentially consequentialist case to offer solutions that will resonate more with non-consequentialists, but surprising to have that degree of emphasis on non-consequentialist solutions

Thank you for the review, I look forward to reading the book. I'm curious whether there are any changes to Singer's views on killing animals and replaceability arguments in the books. In the previous versions of Animal Liberation and Practical Ethics, Peter Singer seems to argue at the same time that:

  1. If a being is not self-aware and doesn't have a continuous psychological identity, then the satisfaction of their future preferences doesn't matter. 
  2. The creation of a happy sentient being is net-positive.

The combination of these two views seems contradictory to me. If the creation of a happy sentient being is good, surely the continuation of that life should also be good. 

Discussing conscientious omnivorism, on p.191, he writes that he "remain[s] in doubt whether it is good to bring into existence beings who can be expected to live happy lives and whether this can justify killing them."

Two pages earlier, he explicitly notes a change in view:

In the first edition of this book, I rejected Leslie Stephen’s argument (that conscientious omnivorism is good for animals) on the grounds that it requires us to think that bringing a being into existence confers a benefit on that being—and to hold this, we must believe that it is possible to benefit a nonexistent being. This, I wrote, was nonsense; but now I am less sure that it is. After all, most of us would agree that conceiving a child who we know will have a genetic defect that would make their life painful and short would harm the child. Yet if we can harm a nonexistent child, surely we can also benefit a nonexistent child. To deny this, we would need to explain the asymmetry between the two cases, and that is not easy to do.

In terms of 'replaceability', note that even if continuing a (happy) life is good, it doesn't follow that it's better than killing with replacement. The replacement might be just as good, after all. To avoid that implication, you need something like individual-directed reasons to generate an asymmetry between killing and failing to create. (Though even then, it's hard to avoid the conclusion that short-lived happy lives are better than no lives at all.)

Thank you very much for taking your time to provide the quotes, I really appreciate it.

You're welcome!  (To whoever is downvoting their polite comment: why?)

When hens are raised for their eggs, most of the baby roosters who are born as well in the hatcheries get brutally murdered. Animals raised on pastures for meat, are brutally murdered as well. There is no humane way to kill someone who wants to live. Thus, initiatives such as bans on animal factory farm expansion or initiatives to phase out animal factory farms completely appear to be more effective in helping animals long-term than initiatives that improve a little bit lives of a limited number of animals.

It may make a big difference here whether one is coming from a "commonsense" moral perspective (on which brutal killing is intrinsically wrong) or a more consequentialist perspective (on which an overall positive life is better than no life at all, as also discussed in this comment).

Of course, we can all agree that it would be better to prevent net-negative lives from existing in the first place. But the strict anti-killing stance that would oppose even net-happy farmed lives does not strike me as "more effective at helping animals". IMO, you don't help someone by preventing them from having an overall happy life, even if that overall happy life also contains some bad experiences. We should only want to prevent bad experiences all else equal, not when it entails also preventing greater positive experiences for that same individual.

I oppose creating “net-happy farmed animal lives” when animals will be killed by humans because when someone is created to be used their whole life and then murdered, I don’t see that as an optimally happy life. It’s like a woman giving birth to a child only to murder them at age 3. It’s better not to plan to have the child and not to conceive them in order to murder them later. If I have a child and love them my whole life, help them, and never want to use them for anything, then this is an optimally happy life. Also, I have cats and never want to use them for anything that they would not want. I only give them unconditional love and feed them a vegan diet according to information I got from a veterinarian who specializes in cat nutrition. So my cats have optimally happy lives. I believe humans should stop breeding other individuals in order to use and murder them. It’s better overall if humans focus on helping others who already share the planet with us or who will be born in the future and help them live optimally happy lives. As for farmed animals who are already born, humans should help them live out their natural lives as optimally as possible and not kill them. This would be overall best net outcome for everyone.


I think happy animal farming (breeding, killing and eating animals who had net-positive lives) is not permissible (except if the animal would be extremely happy). See population ethical arguments against happy animal farming:

Great review! One small comment:

Stick to “pasture raised” eggs. I wish we had more guidance on finding humane milk options; maybe all of the readily-available ones involve calf separation, but are some common brands (e.g. Organic Valley?) at least less harmful than others?

Store bought eggs and dairy are almost certainly coming from factory farms. With regards to Organic Valley:

That's just the calf separation issue I mentioned, right? That's a shame, but I wouldn't lump them together with factory farms (which I associate with daily mistreatment and overall negative quality of life).

It's easy to find Vital Farms eggs at Whole Foods or Amazon Fresh, and they are pasture raised.


"But it’s hard to shake the feeling that farming cognitively disabled humans would be even worse than farming pigs." > I think this feeling is a moral illusion, comparable to an optical illusion where it is hard to shake the feeling that one line is longer than another. I wrote some articles about this: 

And an infographic 


"in principle, it would be a good thing to farm short-lived happy humans (perhaps for their organs) who would otherwise not get to exist at all. But we find the idea repugnant, and that’s probably also a good thing. It causes us to lose out on some life-saving organs, and the value of the farmed lives themselves; but it may also prevent us from committing worse atrocities against each other."> I think people who have the strong moral intuition that it is wrong to use mentally disabled orphans as merely a means (as food, organs, experimental objects) do not believe that those humans are in fact not moral subjects but the main reason why we ought not to use those disabled humans is that we are too stupid to make a distinction between them and moral subjects, that we are not able to draw a line, that when we use them, we will also use moral subjects as merely a means.

About the idea of breeding happy beings to use them (e.g. happy slaves, happy farm animals): it is very difficult to justify this without stumbling upon very counter-intuitive conclusions. I wrote an article about population ethics and animal farming, arguing that happy animal farming is problematic and should also be avoided, even if the animals have net positive lives: 


"It seems tragic for a human to be stuck with the cognitive capacities of a chicken—we feel that they’ve been deprived of capacities that they ought to have had. By contrast, it isn’t tragic for a chicken to have the cognitive capacity of a chicken.">Again, I believe this intuition that one thing is more tragic than the other, is a moral illusion, comparable to optical illusions. It is difficult to justify why one thing is more tragic. So, X and Y do not have property P, but the fact that X not having P is worse than Y not having P is because X looks more similar to Z who has property P? In what sense, and how similar? Or X has parents who have property P? Why parents and not cousins? That seems so arbitrary (comparable to arbitrariness behind optical illusions).


" If we possess a magic pill that would provide typical human intelligence to either individual, it seems we have stronger reason to give it to the cognitively disabled human than to the chicken (bracketing extrinsic factors, like how others would react)."> The only reasons I can think of, are arbitrary, and these are not strong reasons.

Compare: in principle, it would be a good thing to farm short-lived happy humans (perhaps for their organs) who would otherwise not get to exist at all. But we find the idea repugnant, and that’s probably also a good thing. It causes us to lose out on some life-saving organs, and the value of the farmed lives themselves; but it may also prevent us from committing worse atrocities against each other.

This part reminded me of The Promised Neverland.

Thanks for the review, Richard!

Does ALN address these concerns? In particular, I am worried decreasing the consumption of animals will decrease resilience to food shocks.

Not that I recall. (Wild animal suffering is mentioned, but just to support things like bird-friendly window glass, and helping to protect endangered large herbivores that plausibly have better lives than predation-prone smaller animals that might replace them.)

Hi Vasco, I just read certain portions of this document that you linked. My main feedback on this document is that you or whoever is the author does not appear to think that animals who have large brains, such as pigs and cows/bulls, deserve as much compassion as humans. This is what stood out to me in reading this document.

Thanks for the feedback, Rasa! I (the author) have added a footnote saying:

Note I also care about the welfare of large animals like pigs and cows/bulls.