Knut is a superstar. Fifteen thousand visitors a day queue to see the baby polar bear tumbling about in Berlin Zoo with his bearded keeper-cum-surrogate-parent. Since Knut was born in December last year, these same visitors will - going by the European average - between them have eaten approximately 600,000 factory-farmed chickens. Knut enjoys a specially designed enclosure recreating his natural habitat. Each factory-farmed chicken enjoys a space the size of a sheet of A4 paper. Knut has his own blog and has appeared on the cover of Vanity Fair. A battery chicken is killed at the age of six weeks and appears as anonymous chunks of pre-packaged meat on your supermarket shelf.

There is no denying that Knut is cute. Though, ironically, whereas chickens are gregarious creatures that can make affectionate pets, polar bears are ruthless hunter-killers. But the sight of Knut tearing apart baby seals might cause a certain ambivalence among his fan base. So his dinner comes pre-slaughtered; all signs that it was once part of a living, sentient being have been removed - much like our supermarket chicken.

Never has our relationship with the other million or so species of animals with which we share this planet been more dysfunctional. We give our children picture books showing hens clucking round the farmyard with their brood, while feeding them chicken nuggets made from birds that have never seen their mothers and are kept, ankle-deep in their own mess, 20,000 to a barn. We are surrounded by Disneyfied images of animals - from Knut’s blog to that dog that sells insurance. But behind the veil of cartoon cows hides the reality: mass animal testing and factory farming.

At the same time, we are learning ever more about just how closely related we are to our Sunday roast. The animal-testing industry, for example, depends on that very closeness. It’s only because these animals are our not-so-distant cousins that we think that pills that are safe for guinea pigs are safe for us too. Yet it is these cousins that our industrialised food and pharmaceutical industries treat as products to be processed.

Like lions in the zoo, these contradictions are kept locked up by civilised society. When confronted with them, as when we catch the lion’s eye through the bars, we are briefly forced to consider this other being’s half-life - and then we head home for our lamb chops. But three new books are not afraid to open the cage doors and step in.

Linda Kalof and Amy Fitzgerald have collected a group of essays on this subject in The Animals Reader. The Booker Prize-winning John Berger, in his piece ”Why Look at Animals?”, describes zoos as ”an epitaph” to humans’ relationship with other species. Zoos spread across Europe and the US just as industrialisation was causing the disappearance of real animals from daily life. With their disappearance, argues Berger, it became impossible for us to have authentic relations with other species. When horses disappeared from our streets and chickens from our backyards, we were left with Daffy Duck and the Turkey Twizzler.

But unease at this breakdown in inter-species relations is spreading. Television programmes such as BBC Three’s Kill It, Cook It, Eat It - in which guests are invited first to witness their prospective dinner being slaughtered and butchered - demonstrate a desire to look behind the veil. Shocked by what they find there, many are increasingly questioning whether we have the right to do with other creatures what we will. Julian H. Franklin, in Animal Rights and Moral Philosophy, and Marc R. Fellenz, in The Moral Menagerie, both survey these attempts to place animals within our scheme of right and wrong.

The English, as the philosopher Fellenz recognises, have long had a particular affection for their four-legged friends. His book, like the other two, begins with the English moral philosopher Jeremy Bentham, who in 1789 wrote: ”The French have already discovered that the blackness of the skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor. It may one day come to be recognised that the number of the 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.”

Bentham’s likening of our abuse of animals to man’s inhumanity to his fellow man retains the revolutionary power it had more than two centuries ago. J.M. Coetzee pushed the comparison to the pain barrier in his novel The Lives of Animals, in which his protagonist likens the industrialised killing of factory farming to the Nazi death camps. We still talk of those who died in such camps as having been treated like animals, he says, or as having been like lambs to the slaughter.

As Fellenz notes, since the defeat of fascism in Europe we have made great progress in combating racism, as well as sexism and other forms of discrimination against members of our own species. But why stop there?

For Peter Singer, the Australian often described as the most influential living philosopher, the only criterion for whether a creature is worthy of moral consideration is whether it can suffer. Like Bentham, Singer subscribes to utilitarianism, the philosophy that we should always act to minimise suffering and maximise pleasure. As we have every reason to believe that animals feel pain, we should take their interests into account just as much as those of humans. In which case, as Singer writes in the essay reproduced in The Animals Reader, ”it is immediately clear that we must stop treating hens as machines for turning grain into eggs, rats as living toxicology testing kits, and whales as floating reservoirs of oil and rubber.”

But, for all the thousands that Singer has inspired to vegetarianism, his utilitarian reasoning remains problematic. The balance of pain and pleasure may be obvious when rabbits are being tortured to death for the sake of a new lipstick. But in many cases it is incalculable: how do we quantify suffering? Or compare that of a chicken to that of a human? If our personal ethic is that we should always act to minimise the suffering of the animal kingdom we put the burden of the whole world on each of our shoulders. Few of us would be prepared to live like the Jainist monks of India, sweeping the pavement as we walk to spare any insects from our tread. And many of us would buckle at the first whiff of bacon on a Sunday morning.

These failings lead both Fellenz and Franklin to dismiss utilitarianism as a foundation for our treatment of animals, and to turn instead to the question of whether animals have rights. Franklin, in his short but dense book, argues that they do. It would be arbitrary, he believes, to consider some sentient beings, such as our own species, worthy of moral concern, and not others. Reason demands that the basic rights to life and liberty that we grant each other, we also grant to the millions of animals currently in our dominion.

But Fellenz is sceptical. It is difficult enough to give a firm philosophical foundation to rights for humans. In as much as we can make sense of them, they are rooted in the very human institutions of politics and law. But we cannot put a cow under oath. Outside of such institutions, simply to grant all animals inalienable rights ”would risk making the world so sacrosanct that humanity’s very presence in it cannot avoid being morally objectionable”.

Fellenz therefore dismisses animal rights as a noble but flawed idea. In his rich and wide-reaching analysis, he argues that any attempt to extend our ethical theories to animals is doomed to failure. ”Despite the philosopher’s pretence to transcendence,” he says, all these theories ”emerge from within cultural traditions”. And those traditions, based on very human ideas of rationality and individualism, have for centuries been used to justify our dominion over nature. Little wonder then that when we try to extend our moral theories to animals, they collapse in contradiction.

This failure is most obvious when we try to move beyond the farmyard. What sense do rights make on the Serengeti? Do zebras have a right not to be eaten? Should we minimise the world’s suffering by forcing the lions to starve? Nature is filled with endless cruelties. To make it fit our moral categories, we would have to domesticate every last creature, from piranhas to beetles. But then we would have destroyed what we set out to protect.

In Britain, home of the animal-lover, the failure of ethical theory to provide clear answers is most apparent in the debate over fox-hunting. The issue has split the country in two - and largely into town versus country. Matt Cartmill, in his essay in The Animals Reader, acknowledges that hunting is rich in symbolism and tradition. For the aristocracy, it was long an assertion of power, encrusted in elaborate ritual. For the peasant, it was an act of rebellion - Robin Hood was, after all, foremost a deer-poacher. But beneath the veneer of culture and myth, he considers hunting ”just another species of butchery”. And ”butchery is not,” he argues, ”an appropriate recreation for a free people.”

But for another group of thinkers, hunting is an essential part of an authentic relationship with other animals. It is, as Fellenz explains, a near-universal part of traditional human culture. Whereas city folk patronise animals - the poor, ”innocent” fox - the hunter looks them in the eye. ”The respect for the animal of which the hunter is alone capable comes from this intimate acquaintance with the nature of animality, something of a fundamentally different order from humane compassion.” The desire to hunt, which through millennia of evolution flows in our veins, is the desire to enter ”the larger reality of the animal’s world”.

We may accept that the country-dweller, who hunts with hounds and eats lambs from the field next door, has a more authentic relationship with animals than the urbanite who expresses outrage for the poor fox over a plate of (battery) chicken wings. Though we might still debate whether authenticity alone makes every aspect of that relationship right.

But perhaps the worst sin of all is simply to close our eyes to the lot of the creatures we breed in their billions. Whether in the end we embrace the hunt, or turn to vegetarianism, we could at least do those animals that lived and died for our leather shoes and sausages the decency of a moment’s thought. In which case, these three books are an excellent aid. The Animals Reader, in particular, is an immensely stimulating collection of essays, which belongs on the bookshelf of every thinking person.

In confronting animals, argues Fellenz, we hold up a mirror to ourselves. When we look at Knut the baby polar bear on the cover of Vanity Fair, then at the chickens packed 20,000 to a barn, we might ask ourselves what we see.

THE ANIMALS READER: The Essential Classic and Contemporary Writings

edited by Linda Kalof and Amy Fitzgerald

Berg ₤19.99, 448 pages

FT bookshop price: ₤15.99

ANIMAL RIGHTS AND MORAL PHILOSOPHY

book by Julian H. Franklin

Columbia University Press ₤13, 151 pages

FT bookshop price: ₤10.40

THE MORAL MeNAGERIE: Philosophy and Animal Rights

book by Marc R. Fellenz

University of Illinois Press ₤14.99, 301 pages

FT bookshop price: ₤11.99