The contemporary animal rights movement owes a great intellectual debt to Peter Singer's pathbreaking book Animal Liberation . In that book, Singer made a break with the dominant but limited Kantian argument that mistreating animals is a bad - inhumane - thing for humans to do. In its place, Singer advanced a utilitarian case against harming animals - such as by using them for food or experiments - in terms of respecting their right to have their suffering counted equally with that of humans.

Singer's book has had an enormous influence, directly and indirectly, on how many people see the moral status of animals. I include myself among them. Nevertheless I am not sure it is a good book. Despite its rhetorical effectiveness and despite going through multiple revised editions, Singer's official utilitarian argument is far from compelling.

This is a problem for the animal rights movement. For if Singer's case depends on a rhetorical bait and switch rather than philosophical rigour, then the intellectual respectability it has granted the animal rights movement is a sham. Singer's utilitarianism can't do the job it is supposed to do - it can neither justify the book's normative conclusions nor meet the minimalist standard of internal coherence.

Furthermore, the domination of Singer's flawed argument in the intellectual self-understanding of the animal rights movement may be crowding out other more relevant ethical accounts, most obviously those that directly engage with sentimentalism rather than being embarrassed by it.

I here want to focus on the utilitarian case for vegetarianism in the most recent (2002) edition of Animal Liberation , which I believe is mistaken or incoherent in various ways. Some readers may consider my treatment of Singer uncharitable and perhaps even petty - making mountains out of molehills. But, firstly, Singer's approach to applied moral philosophy prioritises rigour and charges of inconsistency are central to his critiques of alternative views. So it is only fair to scrutinise him in the same way. And, secondly, one thing I want to show is that Singer's commitment to the utilitarianism form of argument undermines the resources in his own book for alternative and better moral justifications for vegetarianism.

What is my part in the struggle between good and evil?

Singer explains that the suffering of livestock animals is a real and great evil and directs people to become vegetarian (or vegan if they can) on the grounds that this will undermine the economics of industrial farming and thereby reduce the amount of animal suffering in the world. I agree that the livestock industry is a great evil and the world would be a better place without it. But I disagree with Singer's logistics (as do others). He explains why the reader of his book should become a vegetarian as follows:

"Becoming a vegetarian is a highly practical and effective step one can take toward ending both the killing of nonhuman animals and the infliction of suffering upon them ... Although we cannot identify any individual animals whom we have benefited by becoming a vegetarian, we can assume that our diet, together with that of the many others who are already avoiding meat, will have some impact on the number of animals raised in factory farms and slaughtered for food. This assumption is reasonable because the number of animals raised and slaughtered depends on the profitability of this process, and this profit depends in part on the demand for the product. The smaller the demand, the lower the price and the lower the profit. The lower the profit, the fewer the animals that will be raised and slaughtered. This is elementary economics ..."

The problem here is a very general one for utilitarian ethics in the context of collective action problems. Singer quotes Jeremy Bentham's famous slogan, "Each to count for one and none for more than one." But the second part of that slogan already indicates the practical problem with utilitarianism as a motivator of individual behaviour.

Utilitarianism is concerned with making a difference - bringing about a better world. One is morally required to choose that course of action that will bring about the best consequences according to your idea of what is best (according to Bentham, maximising the predominance of pleasure over pain). But this moral obligation requires that one be in a position to make a difference with one's actions, and not all agents are in that position. Some agents, such as governments or large corporations, possess to some degree a panoptical view of the world and how it works, and the power to make major changes to it for better or worse. Most ordinary individuals do not. That is why utilitarianism is rather better suited to thinking about government than to guiding individual morality. (Not surprisingly, Bentham himself wrote mostly on legal reform, where great increases in aggregate happiness can be achieved with the stroke of a pen - such as by the legalisation of homosexuality.)

The problem with Singer's mechanism is that consumer "votes" against factory farming, like votes in democratic elections, cannot be justified as a means to an end. In both cases, large numbers of people are involved and the mechanism for counting is not sensitive enough to discern any difference from a single individual choosing one way or another. In the case of elections, for example, the voting system's error rate - hanging chads and mistakes by vote counters - is greater than the difference one voter could make. It is therefore irrational to believe that your choice can make a direct causal difference to the outcome one way or another.

Likewise, if you become a vegetarian you will not achieve anything by your consumer choices because they cannot be counted by the animal products industry. Animal products are distributed through a myriad of intermediaries, from hot dog stands to supermarkets, which can only crudely match their inventory planning to sales (rainy days sell less hotdogs).

So the first question is who will notice that you are boycotting meat and stock less? Is it the same people who notice when you go on holiday, or when someone dies? The livestock industry itself operates on a vast scale with very high wastage rates (animals that don't even make it to the product stage). So the second question is which chicken farm will buy fewer chicks because you don't eat chicken anymore? The feedback mechanisms between demand and supply in this industry are just too crude for an individual's choices to have any effect.

There is thus a practical incoherence - a basic failure of logistical analysis - to Singer's utilitarian argument for vegetarianism that reflects a general challenge to consequentialist ethics. (The same problem affects consumer votes about all sorts of things, from vivisection, to greenhouse gas emissions, to recycling.) Even if most people are persuaded about the unnecessary badness of some state of the world, that is often insufficient to determine what they should do about it as individuals. Utilitarianism is supposed to be concerned with good achievements, not good intentions. The fact is that becoming a vegetarian may make you feel better, but it won't save any animals directly. It is not the utilitarian thing to do.

Of course, individuals can still try to "do their part," and it is true that if lots of people act in the appropriate way the right aggregate consequences may be realised (just as if lots of voters choose for Scottish independence it will come true). So it is quite rational for Singer to try to persuade lots of people to boycott meat, even if his utilitarian argument to the reader is flawed (or disingenuous). But it would be irrational for the reader - or even Singer himself - to be motivated to stop eating meat by the belief that that choice would make any difference to the quantity of animal suffering in the world.

One would have to reach for some other moral justification that does not rely on such a tight link between means and ends - such as an account of duties in which one does the right thing because it is the right thing to do, not because it will make the world better. Or virtue ethics, in which one tries to be a good person rather than to optimise the state of the world.

A properly utilitarian argument should recommend effective rather than merely well-intentioned actions. And I should say that Singer himself mentions various actions beyond consumer voting, including political mobilisation for reform of animal welfare laws and proselytising for the vegetarian lifestyle. These are ways for individuals to actually affect the outcomes of collective action problems, primarily because they allow those who care most about an issue to have more influence over it. What is strange is that Singer declares that "these methods are not enough" and instead puts so much emphasis on the ineffective method of consumer voting. (Indeed, this disinterest in political and institutional action is a general feature of Singer's rather individualistic approach to applied ethics, also apparent in his analysis of charitable giving.)

But let me turn now from strategy to goals. Here the problem is Singer's conception of utility.

It's the "Greatest Happiness Principle," not the smallest suffering principle

The utilitarian calculus developed by Bentham - his famous "Greatest Happiness Principle" - counts both the pain and the pleasure of each individual and then ranks different possible states of the world in terms of the sum total of pleasure minus pain they contain. Singer maintains the hedonic focus of Bentham but makes a major - and, I think, misguided - change by asserting that the only thing we should count is suffering. Although he identifies the moral status of animals with their capacity for suffering and enjoyment, the actual principle he repeatedly advances only concerns the minimisation of suffering:

"Pain and suffering are in themselves bad and should be prevented or minimized, irrespective of the race, sex, or species of the being that suffers."

The trouble with this is that if one only looks at pain, one gets a very distorted view of quality of life and a poor guide to action, rather as one would expect of a cost-benefit mode of analysis that disdains the consideration of benefits.

Imagine you have to choose between saving person A or person B (it's a thought experiment - probably something to do with trolleys). You are in a position to know that person A will have 10 units of suffering in his life, equivalent perhaps to chronic arthritis for the last few years of his life. But he will also go on to have a million units of pleasure, one thousand times more than any individual has ever enjoyed before. Person B on the other hand will only experience 5 units of suffering and no pleasure whatsoever. According to the principle of minimising suffering, person B will have the better life and you should save him. That doesn't seem a very compelling version of utilitarianism to me.

Let us play the reductio ad absurdum game one more time. Even if we were to succeed in eliminating the livestock industry as Singer hopes, this should be only the start if we take our obligation to minimise suffering seriously. For the world would still be drenched in the suffering of wild animals - their hunger, fear, cold, injuries, parasites and so on. By Singer's logic we should presumably try to eliminate that too. Singer claims that this would constitute playing God, and is beyond humanity's capacities. But I think it is something we would actually be rather good at. After all, we have already saved numerous species from suffering - such as the Dodo.

In contrast, a Benthamite utilitarian argument would be concerned less with the elimination of suffering than with the maximization of net pleasure in the world. It may well be that this is what Singer actually has in mind. But it isn't the argument he gives in his multiply revised book - and remember that I'm trying here to assess Singer's official argument, as opposed to his rhetorical effectiveness in advancing the animal liberation cause.

If Singer had addressed the positive side of hedonism, it might have made his task more difficult. For the Benthamite account sees sentient beings as capable of contributing to the world's sum of pleasure as well as of pain, and this might open up alternatives in the reader's mind to Singer's proposal of bringing an end to factory farming practices through vegetarianism. If no one ate meat anymore, livestock animals would be eliminated and so would all that potential pleasure.

From a Benthamite perspective, the legislator's concern should be to increase the pleasure and decrease the unnecessary discomfort of livestock animals - which, unlike that of wild animals, is under our control - not to eliminate their existence. For example, if drugs or genetic manipulations could be developed that kept chickens feeling happy while crowded on top of each other, hedonic utility would be maximised. In that case, one might even reverse Singer's argument for a consumer boycott of meat and say that we would actually be doing our moral duty by continuing to eat animals.

Why limit ourselves to the suffering humanity inflicts?

The phenomenological experience of pain is an evolved feature of most vertebrate species, and perhaps at least some others, presumably because it informs individuals of physical injury in time for them to do something about it and this makes survival more likely. It follows that members of these species all feel pain on a regular basis, that pain is a natural feature of the natural world (and part of the modern problem of evil that theists have to deal with).

Yet, if suffering is bad in itself, why does it matter whether it is brought about by disease, weather, accident, hunger and predators in the wild or overcrowding and beak cutting in industrial farms? At least it is not clear to me why a professed utilitarian like Singer should focus only on human induced suffering.

Utilitarianism as a doctrine is supposed to be focused on realising the state of the world one considers best, without consideration of how that state is brought about. Indeed, the narrowness of moral reasoning imposed by this informational restriction is a standard objection to utilitarianism. Utilitarianism is required to ignore agent relativity, the moral intuition that it matters who is the one to do something or to whom something is done (as well as issues like fairness and categorical principles like "Don't torture").

Singer's focus on the suffering inflicted on animals by humans seems to be motivated by something beyond the presence of remediable suffering - the fact that humans are moral agents able to appreciate the wrongfulness of our actions. In particular, Singer's disinterest in wild suffering or that indirectly produced by cereal agriculture seems to reflect widely shared but non-utilitarian intuitions about a moral hierarchy of means. We generally consider ourselves morally more culpable for deliberately harming another sentient being merely to further our interests (as in the livestock and vivisection industries) than for causing suffering as a foreseeable but unintended consequence of justifiable actions (such as the field mice killed by harvest machinery) than for merely allowing suffering to go on (such as foxes eating the same mice).

The irony of this reading of Singer is that, if he does consider suffering deliberately caused by "the tyranny of human over nonhuman animals" to be of special moral significance, that undermines his central claim about the equality of suffering as well as his credibility as a utilitarian. But this is not the only problem with Singer's commitment to equality between human and non-human animals.

On interests, feelings and spines

"[T]he only legitimate boundary to our concern for the interests of other beings is the point at which it is no longer accurate to say that the other being has interests. To have interests, in a strict, nonmetaphorical sense, a being must be capable of suffering or experiencing pleasure. If a being suffers, there can be no moral justification for disregarding that suffering, or for refusing to count it equally with the like suffering of any other being. But the converse of this is also true. If a being is not capable of suffering, or of enjoyment, there is nothing to take into account."

Singer's single most significant and enduring contribution to the animal rights debate is relatively simple. Directly channelling Bentham, Singer has argued that the question that matters in considering the moral status of a life-form is not "Are they human?" but "Can they suffer?" Singer characterises those who give moral priority to humans as "speciesist," a term deliberately intended to evoke emotive comparisons with the irrational prejudice of racism and sexism.

Yet I wonder if Singer himself has not inadvertently promoted another -ism of his own by fetishising the particular mode of the experience of suffering that humans find most familiar. One might call this "spinism," since most of the species to whom Singer extends his moral concern - those that seem to feel pain like we do - are vertebrates.

Singer declares that his concern is to take the interests of non human species into moral account. But like a good hedonistic utilitarian he asserts without argument that the possession of interests requires a human-like phenomenology:

"The capacity for suffering and enjoyment is a prerequisite for having interests at all, a condition that must be satisfied before we can speak of interests in a meaningful way."

This is clearly false. It doesn't even seem particularly difficult to speak meaningfully of the interests of living organisms that lack the capacity for human-like suffering and enjoyment. Take the case of plants, which Singer rejects with little more than a sneer. Individual plants have obvious interests in their own welfare (in surviving, thriving and reproducing) and one can even rank these in order of priority - obvious intermediate interests in getting enough light, water and micro-nutrients, defending themselves from predators, and so on.

Nor is does it seem impossible to take the interests of non-animal life into moral account in our actions. Jains, for example, a well-known religious group with several million members, interpret their moral-religious duty of non-violence as requiring them not to kill any life-form, and try to live up to that by only consuming food from plants in a way that does not kill the plant. (In addition, a case can now be made for plant "sentience," based on more recent empirical research than was available when Singer last revised his book in 2002.)

Singer seems to deny that plants have interests because, like stones, there is nothing there to have them. He doesn't explain this further, but it seems to rely on an implicit understanding of subjectivity: plants are not subjects able to relate conceptually to what happens to them. But Singer's only criterion for subjectivity is sensation - possession of a nervous system - and this seems insufficient to establish a categorical distinction between the interests of plants and animals. Merely because non-human animals have a physiological capacity for pain and pleasure that helps them meet their welfare interests in bodily health and integrity doesn't mean that they have subjectivity, that they relate to pain in the same conceptual self-evaluative way that humans do (I owe this point to Ian Hill). It seems that only a few animals posses this cognitive faculty to any significant degree.

The upshot is that both plants and non-human animals can equally be said to have interests in their own welfare, and for animals that would include a dimension - sensation - which plants don't seem to have because they lack a central nervous system.

I'm not trying to argue here for plant liberation. My point is rather that, on an impartial view, sentience seems a gradualist and multi-dimensional phenomenon rather than a categorical one. And that, while the sensation of pain/pleasure certainly seems of some moral significance, Singer's assertion that only sensation matters is rather unconvincing. However, the way Singer has set up the argument of this book for the moral equality of animal suffering means that he has to insist on its fundamental simplicity: "Can they suffer?" The inconvenient topography of sentience, and the hierarchy of interests it implies has to be flattened out, lest the reader conclude that something more sophisticated than hedonic utilitarianism is required.

But this equation of interests with sentience and sentience with pain is not only an unreasonable move in itself. It also seems to repeat the self-serving closed mindedness for which Singer criticises speciesists so strongly.

If not utilitarianism, then what?

When we put all these critiques together, there seems little left of Singer's claim to have established animal liberation "as a cause founded on basic principles of justice and morality." His official utilitarian argument is either unconvincing or not really very utilitarian after all.

Yet perhaps it doesn't need to be for the book to do the job Singer wants. Indeed, little of the book consists of explicit moral arguments (just a few pages in the introduction, and parts of two later chapters) while the bulk of it consists in systematic description of the horrors of factory farming and vivisection. Perhaps this is the time to confess that I was convinced to become a vegetarian by reading Singer's book, despite my misgivings about his official arguments, simply because the horror piled on horror that is factory farming doesn't need very rigorous argument to convince you once you are pointed in the right direction and persuaded to open your eyes. Factory farming is a great and terrible evil and I want no part of it.

What won me over was not the rigour or deftness of Singer's intellectual moves, but a much more basic reshaping of my moral sentiments. I don't feel a triumph of rationality over desire. I didn't conclude that I should stop eating meat because that would make the world a better place. Rather, I found my tastes themselves changed by the moral recognition of the significant degree of sentience of many non-human animals - their possession of personalities, emotional states and even firm opinions on some issues like favourite kinds of grass. (Incidentally, Singer makes positive reference to Darwin's conclusion that many non-human animals exhibit some degree of the faculties of love, memory, attention and curiosity, imitation, reason and sympathy for each other - but of course he couldn't do anything with it without endangering his categorical definition of sentience.)

The repugnance I have come to feel about eating such animals is an extension of what I would feel about eating my pet cat rather than the product of some calculation of quanta of suffering. My vegetarianism is built up from my moral sentiments, a reluctance to be complicit in the infliction of unnecessary suffering on sentient creatures that might be characterised as a kind of moral disgust for cruelty. Unlike Singer's highly theoretical official justification for vegetarianism, mine is visceral, muddled and inconsistent, as I think much of real moral life must be.

Complicity is the ethical concept for analysing one's moral responsibility for intentionally participating in a collective practice that is wrong in itself or that brings about wrongful harms. In contrast to a consequentialist ethic, it doesn't depend on causally tracing one's own particular contribution to those harms. It seems to me that the importance of avoiding complicity in evil is hiding in plain sight in Animal Liberation. Singer often says things like this:

"Vegetarianism brings with it a new relationship to food, plants, and nature. Flesh taints our meals. Disguise it as we may, the fact remains that the centerpiece of our dinner has come to us from the slaughterhouse, dripping blood."

Yet he always pulls back to his official utilitarian line and its implausible logistics:

"The point of altering one's buying habits is not to keep oneself untouched by evil, but to reduce the economic support for the exploitation of animals, and to persuade others to do the same."

***

Let me conclude with a brief turn to theory, beginning with the argument that Singer's book intended to overthrow. Although he was no friend of sentimentalism, Immanuel Kant provided an influential argument for people having duties to treat animals well, on which the original animal welfare movements of the nineteenth century drew. Although he believed that:

"So far as animals are concerned, we have no direct duties. Animals are not self-conscious, and are there merely as a means to an end. That end is man."

He also argued that:

"If a man shoots his dog because the animal is no longer capable of service, he does not fail in his duty to the dog, for the dog cannot judge, but his act is inhuman and damages in himself that humanity which it is his duty to show towards mankind. If he is not to stifle his human feelings, he must practice kindness towards animals, for he who is cruel to animals becomes hard also in his dealings with men."

It seems to me that, despite its own intellectual rigour, Kant's view on this point is rightly seen these days as rather more dogmatic than convincing. Yet I do think that he got something right, and that something remains implicit in Singer's strangely un-utilitarian arguments: the morality of our interactions with animals is principally about us, not them. Our goal should be to end "the tyranny of human over nonhuman animals," not to maximise net happiness. That's why it matters that their suffering is inflicted by humans for no justifiable reason; that's why we should stop eating their "corpses." But this is something neither Kant nor Singer are quite able to get at because both are committed to theoretical approaches to moral philosophy that are deeply suspicious of an independent role for sentiments.

Is it wrong to act from sentiment rather than reason? Yes, if you are a utilitarian or a Kantian. No, if you are something else, like a virtue ethicist. Virtue ethics is concerned with moral character - with what kind of person you should try to be rather than what kind of actions you ought to do. Among other things, it incorporates moral sentiments into moral reasoning rather than setting them in opposition.

Most people are natural virtue ethicists, even if they don't know it, because it more or less reflects our commonsense understanding of moral psychology. It was central to scholarly work on moral philosophy for a very long time, up until the rationalism of the Enlightenment - the influence of thinkers like Kant and Bentham - made its lack of rigour unfashionable.

This is the account I find most adequate to the justification of my own vegetarianism. We should not be complicit in consumption practises that inflict suffering upon animals, not because the total amount of suffering in the world is too high, but because cruelty is something we should recoil from.

Thomas Wells is a philosopher based in Rotterdam. He blogs at The Philosopher's Beard. This is a heavily revised and expanded version of an essay originally published on 3 Quarks Daily.