The primatologist Frans de Waal tells a story about a bonobo. One day, a starling smashed into the glass of the ape's enclosure and fell to the ground. The bonobo approached the stunned bird and set it on its feet; the bird failed to move. So the ape carried it to the top of a tall tree, unfolded its wings and set it free like a paper aeroplane. But the starling spiralled back to the ground. The bonobo descended the tree and protected the bird for some time. Eventually, the bird recovered and flew to safety.

De Waal's interest is scientific. Bonobos apparently show empathy, an ability to imagine the circumstances of another creature - another species, in this case. But when he tells the story, he is making a moral point, too. We human beings, by analogy, are not machines run by selfish genes. "We are born with impulses that draw us to others and that later in life make us care about them," he writes in his book Our Inner Ape.

His story resonates powerfully today, as it seems that this capacity has become little short of a panacea for our moral ills. It will solve the climate crisis, according to Jeremy Rifkin, author of The Empathic Civilisation. It is the "core of our humanity", says the novelist Ian McEwan, who has argued that the 11 September 2001 hijackers "would have been unable to proceed" if they had had empathy for their victims. It's as if there's a collective sigh of relief that we're not lonely souls, inferring what's going on inside another person's head as we gaze out of our own, as philosophers have told us; we know others from the inside. But does de Waal's story feed a sentimental myth? Can empathy achieve such dramatic moral gains for us?

“There is a danger in using the word too loosely," believes Lynne Cameron of the Open University, who is engaged on a three-year programme to understand the dynamics of empathy. She refers to the rhetoric as "deceptive" and "disturbing". The difficulty is this: empathy can be defined as stepping into someone else's shoes, but have you ever tried it? Your imaginative exercise might evoke concern for the Chinese factory worker in Shenzhen. Yet it can also provoke antipathy. What is consumer culture, if not an exercise in mass empathy, powered by the desire for the shoes of the rich and famous, because you long to wear them, too? Empathy is morally ambivalent.

Ethical dilemma

Psychologists differentiate between automatic and deliberative empathy. Automatic empathy is the kind investigated by neuroscience - research shows that when we see someone in pain, say, the same brain areas are activated as when we ourselves are in pain. "The importance of these results is that they show that we are much more embedded in the social world of other people than we realise," says Chris Frith, emeritus professor at University College London, who works with the Interacting Minds project at Aarhus University in Denmark.

But it is deliberative empathy that interests Cameron. Her research has focused on the relationship between Jo Berry and Patrick Magee. Magee planted the bomb in the Grand Hotel in Brighton, 20 years ago, that killed Jo's father. Berry exhibits deliberative empathy in her unusual willingness to engage with Magee. The thought alone would repel many people, and their meetings are typically stressful. But that is what makes Berry so remarkable. She has powers of determination and a personal ethic that strives for reconciliation. Cameron notes that such admirable behaviour requires an individual to be both emotionally mature and open to moral deliberation. That can overcome the ambivalence inherent in automatic empathy - though the tougher the situation, the tougher the personal challenge.

The ambivalence of empathic responses is further complicated when you consider what happens between groups. Another factor comes into play: "us and them", as the author David Berreby puts it in a book of the same title. A recent study, published in Science, examined how men in teams behave when they are dosed with the "bonding hormone" oxytocin. The individuals who took the hormone behaved more generously towards others in their own group, as might be expected.

However, the same people were significantly less likely to co-operate with individuals from a different group. This suggests that our empathic responses depend on our beliefs about who is "with us" or "against us". To put it another way, oxytocin could equally be called the "dividing hormone" - the reaction depends on the circumstances.

Given all the ambivalences, can we say what empathy is? An answer is to be found in the history of the word - which is, in fact, only 100 years old. It is a translation from the German Einfühlung, or "feeling into", which itself was a neologism of 1873, according to Carolyn Burdett, a lecturer at Birkbeck College, London, who is writing a history of empathy.

Moving pictures

Empathy's first British populariser was one of the most striking women of the Victorian age, Vernon Lee. Known as "the cleverest woman in Europe", Lee deployed the new word in her theory of aesthetics. She sought a link between beauty and morality, and believed she had found one in a study of her friend Clementina Anstruther-Thomson, or "Kit". Lee noticed that Kit would stand before artworks and spontaneously show their value in her physiological responses - a slight shortening of the breath, a gentle rocking on her heels.

Lee reckoned the reaction came about by a process of projection. The artwork caused changes in Kit's body because she unconsciously loaded the work with her feelings and beliefs. That in turn caused her to apprehend the work in a specific way. She was "feeling into", as the German Einfühlung had it. So Lee called the process "empathy".

Such projection helps explain the ambivalences. The psychology suggests that an individual who sparks an empathic response in you does so, at least in part, because of what you read of yourself into them. Hence, you might warm to them, but you could also be blinded to their predicament, which is why psycho­analysts are often wary of empathy. You might be appropriating them for your own needs, brutalising them. Furthermore, if empathy has something to do with morality, it is also implicated in masochistic behaviour.

“If we want to retrieve what's morally good about empathy," Burdett reflects, "we have to acknowledge these ambivalences. I've come to regard empathy as a process, not an act; as a task, not a response." It is part of what tells us we are with others, but working out how we will behave towards others is a personal, political and moral challenge - as it always was. To believe otherwise, as implied in the rhetoric of expanding circles of empathic concern that grow to encompass the whole of humanity, is not just deluded; it's dangerous. Empathy's ambivalences unchecked might not result in just compassion fatigue, but compassion collapse.

Mark Vernon is the author of "The Meaning of Friendship" (Palgrave Macmillan, £9.99)

Aesthetic pleasures: the life of Vernon Lee

Vernon Lee was the pseudonym of Violet Paget, a Victorian author and essayist who was a strong advocate of the late-19th-century aesthetic movement. Born to British parents in France in 1856, Lee mostly lived away from Britain. Her longest place of stay was the ancient Residenza del Palmerino, just outside Florence.

Lee's first published work was Studies of the 18th Century in Italy, which appeared in 1880, and gave her an entrée into the intellectual elite of the day. On her first visit to Britain, in 1881, she met Walter Pater, the founder of the aesthetic movement, and his disciple Oscar Wilde. A flurry of publications followed, including Euphorion (1884), a work that established her as a writer on art and the Italian Renaissance.

In the early 1890s, she began a long-term lesbian affair with Clementina Anstruther-Thomson ("Kit"), who inspired Lee's theory of psychological empathy and its connection to fine art. As well as her scholarly reputation, Lee attracted praise for her short fiction, such as the 1884 novella

Miss Brown, a satire on the Pre-Raphaelite circle, and Hauntings (1890), a collection of short stories about the supernatural. In the years following the First World War, she withdrew into comparative isolation, and died at the Palmerino villa in 1935.

Caroline Crampton