Moral sceptics have always liked to point to the phenomenon of cultural disagreement in order to undermine absolute claims in morality. Already in antiquity Sextus Empiricus, the most important author of the sceptical Pyrrhonist school, pointed out the wide variation in norms and customs around the world. Particularly attention-grabbing are his claims about sexual morality around the world: the Persians marry their mothers, the Egyptians their sisters! But he also mentions that foreign peoples are more tolerant than the Greeks are when it comes to things like theft, infanticide and cannibalism. Still today, one of the most powerful arguments for ethical relativism comes from cultural relativism. Who are we to say that the beliefs and behaviours of other peoples are wrong? Wouldn't they say the same about us? You've probably heard just this line of argument if you've ever been in a philosophy class. Taken to its logical extreme, it would put moral disagreement on a par with differences in manners. Some people eat with their fingers, some use chopsticks, some use a fork and knife; just so, some people are relaxed about theft, while others punish it severely.

The usual response to this move is to mention some kind of extreme moral abomination, to remind the relativist that their tolerance probably has its limits. Of course you won't object to eating with fingers, when and where it is culturally appropriate. But you'd be hard pressed to accept that, say, inflicting pain and suffering on innocents for fun is wrong only by the moral code of our society. The same goes for cultures that are removed from us in time, rather than place. We typically think that the abandonment of certain practices of the past, such as infanticide and slavery, are a mark of moral progress. If there is a lingering uneasiness with this sort of argument, it is perhaps because the moral beliefs of other cultures are being measured by our moral standards. This looks judgemental and arrogant: we know better than they do, or did. Ironically enough, we here come into conflict with other values we tend to cherish today, like tolerance and open-mindedness.

So here is another way to respond to the relativist: point to moral beliefs of other cultures that are better. This avoids the charge of cultural imperialism, while supporting the idea that there are general, objective truths in ethics. A nice example would be one that, as it happens, was also mentioned by Sextus Empiricus: the fact that some other ancient cultures did not allow the eating of meat. Famously, large parts of India are still vegetarian, which goes back to the fact that religious traditions there – especially the Buddhists and Jains – have avoided violence against animals for more than two thousand years. Ancient India, then: here is a culture that could rightly condemn modern Western culture, at least on this one issue. You'll be especially inclined to agree with that if you are yourself a vegetarian or a vegan. But even if you aren't, you would probably admit at least that the evils of factory farming are indeed evils, and that a more humane approach – one that would bring our practices closer to those of the ancient Indians – is needed.

But before leaping to conclusions, we might want to ask why ancient Indians were so reluctant to inflict harm on animals. Doing the right thing is obviously good, but doing the right thing for the right reason would be even better. Here we run into a bit of a surprise. Nowadays, vegetarianism is occasionally motivated by health concerns or environmental concerns. But usually the reason given is that eating meat violates the rights or interests of animals. As Isaac Bashevis Singer put it, ‘I did not become a vegetarian for my health, I did it for the health of the chickens.’ By contrast, the original impulse to show benevolence towards animals in India was arguably a selfish one. Violence against them, indeed violence in general, was thought to incite retribution, perhaps in the next cycle of incarnation. Thus some, especially those who adopted an ascetic or ‘renouncer’ way of life in defiance of traditional Vedic culture, followed the principle of ahimsa: ‘non-violence’.

On this interpretation, the apparent moral heroism shown by some of these renouncers was just that, only apparent heroism. You may know how Jain monks, in particular, avoid travelling in the rainy season, sweep the ground in front of them as they walk and strain their water before drinking, to avoid inadvertently killing insects and other minute creatures. Another rule is to abstain from using fire, and for the same reason: bugs might fly into the fire and be immolated. While this looks like the most extreme form of care for other living things, it might actually be an extreme form of care for the self. In the Indian context, a theory of karma was used to explain the reward and retribution meted out to people for their actions. The Jains compared karma to ‘dust’ which sticks to the soul, and thought killing another living thing was a paradigm way of attracting the particles of bad karma. They feared that the karma acquired by harming animals, even insects too small to see, could require them to live again so that that harm could be requited.

At this point the Indian ethic of non-violence is starting to look less attractive. The whole project concerned the interests of the individual moral agent, not those who were being spared violence, whether animals or other people. So this was, it seems, not really even moral behaviour. It was just calculated self-interest. But again, we should not leap to conclusions. This line of criticism threatens to do what we were trying to avoid, by imposing our own moral beliefs and intuitions on the people of another time and place. To demand that vegetarianism should be motivated by the interests of animals, if it is to be properly moral, is to assume that all moral behaviour worthy of the name must value the interests of others. But this isn't how ancient morality usually worked. In ancient Greece, ancient China and ancient India, we find what philosophers call ‘eudaimonist’ ethics. The name comes from the Greek word eudaimonia, which just means ‘happiness’. (I guess we call it ‘eudaimonist’ because ‘happiness ethics’ sounds ridiculous.) The idea here is that a moral agent ought to be virtuous because it is good for the agent to be virtuous. It will make them happy, not in the sense of being merely satisfied or content, but in the sense of enjoying a well-rounded, flourishing life.

In general, there is a puzzle about how eudaimonist ethics can explain altruism. This means acting for the benefit of others, especially when it undermines one's own apparent interests. The Greeks would unhesitatingly assume that a virtuous man should die for the sake of his family, or city. How would that be a way for the virtuous man himself to be happy? Well, remember that what we're after is living a flourishing overall life, not just living as long as possible. It would actually be worse for the moral agent to live to a ripe old age, if he could only do it by showing cowardice. Of course a virtuous person will still benefit fellow citizens, friends and family members by performing excellent actions. But these actions are ultimately taken towards the end of that individual person's own fulfilment and happiness. The benefits conferred on others are only a kind of happy by-product. The same, then, could go for the cow or insect that goes unharmed by the vegetarian, cautious, fire-avoiding Jain monks. What the monks are trying to do is to live a blameless life. In furtherance of this goal, they eschew violence against cows, insects, indeed all living things. Even plants were thought to be potential recipients of violence, but harm against them is of a lower order than harm against animals, so they may be eaten as (literally) the lesser of two evils.

The eudaimonist nature of Indian ahimsa fits with the way that Jain and Buddhist monks actually got their food. Normally they received it in the form of donations from laypersons, that is, adherents of the same religious tradition who had not sworn themselves to the rigours of monastic asceticism. In theory at least, the food given to the monks was ‘left over’, not made with them in mind. Just as a modern-day vegetarian might be willing to eat roadkill or meat that would otherwise have been thrown out – no sense in letting it go to waste – so these monks were willing to take advantage of violence committed by others. Jains would, for instance, accept boiled water prepared by laypersons, since it was the laypersons who were using the fire, and who would be on the hook for killing any stray insects. Buddhists even allowed themselves to eat meat not intended originally for them, something the Jains considered to be crossing the line. They in fact polemicized against the Buddhists and spoke as if this concession amounted to bloodthirstiness. But the Buddhists justified the practice on the same grounds invoked by the Jains.

It might seem strange to suppose that someone can avoid blame just by getting someone else to do the dirty work. Within a eudaimonist framework though, it makes a certain amount of sense. What matters is the individual moral agent, not the network of actions being performed by other people around them. In particular, in ancient Indian eudaimonism what mattered was the agent's intentions. What led to the build-up of bad karma was forming violent intentions, as well as acting on them. This is illustrated by a Jain story about a king who sought to preserve his moral purity, and thus avoided killing animals in ritual sacrifice. Instead, he sacrificed a ‘rooster’ that was in fact made of flour. To the king's surprise and horror, he arrived in the afterlife and found himself being punished. His intention in the sacrifice had been violent, no less than if he'd slaughtered a real rooster. The story sheds further light on the monastic practice of accepting food prepared by laypersons, who may have committed at least minor acts of violence (e.g. lighting fires) to make the food. It was not a case of moral free riding, but came down to the question of who had formed, and acted upon, violent intentions. The monks were simply taking leftover food. Things would have been very different if they had deliberately incited the laypeople to make them dinner.

Again, we see that within this eudaimonist framework, what is wrong about harming animals is not that one infringes the animals’ rights or interests. Rather, it is that the harmful action would be an expression of a disruptive, violent mindset, one bent upon destruction rather than harmony with the world. Vegetarianism, and more generally non-violent action, was really just a by-product of a peaceful, contented and effortlessly controlled inner state, one that required years of practice to attain. In the case of the Buddhists, it would be the outcome of having taken on board the Buddha's teaching that desire leads inevitably to suffering. Through long and rigorous ascetic discipline, desires could be quietened and ultimately eliminated. The result would be deep compassion towards other people and living things, embodied in what the Buddhists called ‘skilful action’ (kusala), action that grows from a correct understanding of things. So this was far from a self-interested moral theory. Such action can never flow from violent intentions, which are the ultimate example of desire flowing from attachment to things like wealth or pleasure. It's attachments like these that make people fight wars, argue with their family over inheritance, and yes, eat meat.

At this point one might imagine a critic speaking up. If it is intention and not results that matter, then shouldn't it be all right to commit ‘violent’ actions so long as they do not stem from a violent state of mind? Actually we don't need to imagine a critic saying this, because the point was actually made by opponents of the Buddhists and Jains in Indian antiquity. The most famous example is in the Bhagavad Gita, a philosophical interlude found in the enormous epic called the Mahabharata. In the Gita, a warrior named Arjuna refuses to fight in a war against his own kin, but is then persuaded by the god Krishna that he should pick up his bow and join battle. In so doing, he will simply be submitting to his path and purpose. To forestall the worry that this would require violence on Arjuna's part, Krishna sets out a theory of ‘unattached action’. Arjuna should simply do what he is meant to do and solely because he is meant to do it, without minding one way or another about what results.

The Gita draws an explicit parallel between Arjuna's situation and the case of ritual sacrifice. It argues that slaughtering an animal and offering it to the gods out of ‘devotion’ (bhakti) is far from being disharmonious and disruptive in intention. To the contrary, it is a case of the purest piety, a submission to the divine cosmic order that ‘holds the world together’. Another text of the Vedic tradition, the Laws of Manu, likewise states that ritual animal sacrifice is not, contrary to appearances, a violation of the ethic of non-violence, because it is not undertaken out of violent intentions but out of religious duty. As we can see, the Vedic tradition too accepted that non-violence is a worthwhile principle, perhaps under pressure from the renouncer movements. So Vedic authors had to present traditional sacrificial rites as being in accordance with this principle. Their rationalization may look like a loophole, but if so, it was one much too narrow to accommodate a casual steak dinner.

From all this I would conclude that the ancient Indian ethic of non-violence does offer a worthwhile perspective on the much-discussed issue of animal welfare. Living in a world dominated by utilitarian considerations, we tend to evaluate moral actions based on their concrete results. So we may find it hard to relate to benevolence towards animals that is not primarily motivated by a concern to minimize animal suffering. But there's no denying that the Indian ethic of non-violence did minimize such suffering, and continues to do so today. And there is at least one way that ahimsa could even be a better motive for vegetarianism than the utilitarian calculation of a modern day animal ethicist like Peter Singer. A common justification for continuing to eat meat is that vegetarianism, and especially veganism, are fairly demanding ways to live. The payoff in outcomes doesn't seem to make it worthwhile. Will even a single cow or chicken survive thanks to my living as a vegetarian for the rest of my life? Presumably not, since my individual dietary choices are the tiniest of drops in the enormous bucket of global food demand. So why should I bother?

This is of course a familiar problem. One person recycling, or turning off the lights at home, is not really going to do anything to help avert global warming. One person could donate their entire wealth to charity, without being sure that, as a result, even a single person will avoid starving to death or dying of a preventable disease. Problems of global scale have global magnitude, in comparison to which individual action becomes a mere rounding error. The obvious utilitarian response is to say that if enough people make the right choices, then it will make a difference. If, as some studies suggest, 5 per cent of Europeans are vegetarian, that surely means a real drop in total meat consumption. But the Indian ethical theory offers an additional response to this problem. Even if your choosing not to eat meat will barely help any actual animals, it is going to help you, because it will make you less violent in thought and action. And being less violent is part of being more happy. Something to consider tonight, as you tuck into your dinner of lentils.