In a column for The New York Times this past January, Nicholas Kristof lamented what he called the country’s “empathy gap,” imploring his readers to grasp the complex circumstances that could plunge someone into poverty. Meanwhile, the psychologist Paul Bloom has argued that a sense of empathy can actually be “parochial [and] bigoted,” making it so “the whole world cares more about a little girl stuck in a well than they do about the possible deaths of millions and millions due to climate change.”

For Kristof, empathy is a willingness to understand an individual’s situation, a cognitive and emotional exercise that could in turn inspire compassion. For Bloom, empathy is a blinding emotion that can preclude more rational thinking. In the first case, empathy reduces stereotypical thinking; in the second, empathy as emotion-sharing draws too much attention to an individual, standing in the way of effective social change.

Who’s right? Kristof’s and Bloom’s definitions of empathy seem to be conflicting—but both nevertheless count as empathy. Over its short history, the concept of empathy has been defined and redefined again and again. Ask your friends for a definition and watch its meanings proliferate.

The English word “empathy” came into being only about a century ago as a translation for the German psychological term Einfühlung, literally meaning “feeling-in.” English-speaking psychologists suggested a handful of other translations for the word, including “animation,” “play,” “aesthetic sympathy,” and “semblance.” But in 1908 two psychologists from Cornell and the University of Cambridge suggested “empathy” for Einfühlung, drawing on the Greek “em” for “in” and “pathos” for “feeling,” and it stuck.

At the time the term was coined, empathy was not primarily a means to feel another person’s emotion, but the very opposite: To have empathy, in the early 1900s, was to enliven an object, or to project one’s own imagined feelings onto the world. Some of the earliest psychology experiments on empathy focused on “kinaesthetic empathy,” a bodily feeling or movement that produced a sense of merging with an object. One subject imagining a bunch of grapes felt “a cool, juicy feeling all over.” The arts critics of the 1920s claimed that with empathy, audience members could feel as if they were carrying out the abstract movements of new modern dance.

By mid-century, empathy’s definition began to shift as some psychologists turned their attention to the science of social relations. In 1948, the experimental psychologist Rosalind Dymond Cartwright, in collaboration with her sociologist mentor, Leonard Cottrell, conducted some of the first tests measuring interpersonal empathy. In the process, she deliberately rejected empathy’s early meaning of imaginative projection, and instead emphasized interpersonal connection as the core of the concept.

In the flurry of experimental studies of empathy that followed, psychologists began to differentiate “true” empathy, defined as the accurate appraisal of another’s thoughts or feelings, from what they called “projection.” In 1955, Reader’s Digest defined the term, which was new to the public outside of academia, as the “ability to appreciate the other person’s feelings without yourself becoming so emotionally involved that your judgment is affected.”

In the past few decades, interest in empathy has spread beyond psychology to primatology and neuroscience. In the 1990s, neuroscientists studying monkeys discovered mirror neurons, cells in the animals’ brains that fired not only when a monkey moved, but also when the monkey saw another one make the same movement. The discovery of mirror neurons spurred a wave of research into empathy and brain activity that quickly extended to humans as well. Other recent studies have further widened empathy’s reach into fields like economics and literature, finding that wealth disparities weaken empathic response and that reading fiction can improve it.

But as Kristof and Bloom illustrate, there is still some cultural debate about what empathy means today. And in the psychology community, the answers are no more clear-cut. Critics of the mirror-neuron theory, for example, question not only the location of these neurons in the human brain, but whether simulation of another’s gestures is a good description of empathy in the first place. The social psychologist C. Daniel Batson, who has researched empathy for decades, argues that the term can now refer to eight different concepts: knowing another’s thoughts and feelings; imagining another’s thoughts and feelings; adopting the posture of another; actually feeling as another does; imagining how one would feel or think in another’s place; feeling distress at another’s suffering; feeling for another’s suffering, sometimes called pity or compassion; and projecting oneself into another’s situation.

This last one is closest to empathy's earliest definition, though it doesn't reflect the capacity to feel our way into objects and the natural world. But while empathy no longer means what it did a century ago, we do experience a strange admixture of self and world when we contemplate a weeping willow, describe an imposing tower, or hum along to a happy melody. We can empathize with form, and feel ourselves in the world around us.