Every time I go on Facebook I end up staring into the eyes of a puppy. Sometimes it has been mistreated, has a bad case of mange, or worse. Sometimes it's looking for a home. I feel a tug on my heartstrings: What if I were that homeless puppy? It also makes me feel very important: Only I can save this puppy!

But in real life I have no place for an out-of-state puppy, and I'd rather save my gofundme donation for the friend of a friend who needs help recovering from a bike accident. And so I harden my heart and click on - to watch a cat consoling a crying baby, or Koko the Gorilla showing her distress about the death of Robin Williams.

So goes life in social media, which has become a marketplace for evoking, feeling, displaying, and profiting off the gooey human emotion of empathy. In this new zone, it's not enough to support a cause; we literally become it - by remaking our own profile pictures with a rainbow to show support of gay rights or solidarity with the sufferers of lupus. Here there's an implicit belief that more empathy will make the world a better place.

The only hitch in this scenario are the trolls, who make a great show of having no empathy. They attack those down on their luck with vicious glee. They make statements about which categories of people don't deserve to live. They post photos that make me feel sad and powerless. Freeing themselves from the sticky bonds of empathy is a release, an entry into an upside-down world with political implications, appealing to hyper-individualist Ayn Rand acolytes and those who are just plain mean. Make fun of reporters with disabilities or women who resist your advances, and you'll gain followers, even become president. Not-empathy suddenly appears to be a thing as real and ubiquitous as the original.

Empathy's history demonstrates its great and particular power. In the early 1700s, as religion and aristocracy were faltering, a craze for epistolary novels gripped educated Europeans and began a transformation of their interior sensibilities. By sympathising so thoroughly with desperate heroines in the books they read, people began to sympathise with each other, too, and to recognise each other's humanness.

Recognition of others' interior lives led to the idea of inalienable human rights. First granted mainly to white Christian males, rights were then extended to other races, women and religions, and have given gay people the right to marry. Where will it stop? The human future, to the empathist, is one of ever more recognition, and ever more rights - for animals, trees, the whole planet.

But an emotion that powerful could not be left alone in the 20th century. Historian Susan Lanzoni tells the story of the English word's invention - borrowed from German - in 1907, and its quick repurposing in the treatment of World War II veterans, troubled marriages and as a remedy for a history of racist policies by the 1970s.

It wasn't until the 1990s, with the discovery of mirror neurons, that empathy became something meatier than an emotion. Since then, the study of empathy has partly been driven by researchers trying to understand autism (where people have strong sympathies for others, but have a hard time cognitively understanding how others are feeling) as well as sociopathy (where people have strong cognitive sense of how others feel but do not feel empathy). Using ever more sophisticated tools to figure out where empathy happens in the brain, and how, researchers stripped off the sentimental aspects of empathy and made it scientific.

The weird empathy world of Facebook appears to be only the beginning of a larger process. Advertising, British researcher Andrew McStay concluded in a recent paper, will increasingly make use of both empathy and the web of machines and processors embedded in our lives. He writes that this raises serious "questions about the foundations of the ethics of advertising, i.e. whether it is about free choice of voluntary parties or not".

I initially assumed that the existence of online trolls - those anti-empathisers - meant that not everyone was susceptible to the charms of emotionally savvy machines. But recently I came across a study that put the trolls in a new light. Psychological researchers Natalie Sest and Evita March surveyed online trolls, who are more likely to be male, and found that they understand empathy all too well. "Trolls employ an empathic strategy of predicting and recognising the emotional suffering of their victims, while abstaining from the experience of these negative emotions. Thus, trolls appear to be master manipulators of both cyber settings and their victims' emotions."

In other words the trolls, the dog videos, and the gofundmes are all the same thing: a kind of manipulative empathy nightmare, an empathology. The Internet has enabled the weaponisation of empathy, for both good and ill. In the future, empathy could also tear us apart - in a painfully individualised fashion.

So it's only reasonable to take empathy more seriously, not only as a soft persuasive power, but as one with serious consequences. Regulate its use in devices and games and advertising. Stop designing social media to explicitly exploit empathy and its pathologies. Stop staring into puppies' eyes.

And more deeply, reconsider the assumption that empathy will save the world. Even with the best intentions, empathy has always been an untrustworthy moral compass. By prioritising emotional interaction as more genuine than intellectual engagement, empathy seems to offer a shortcut to moral answers and significant understanding. But it can also be a shortcut to the opposite.

• The writer is a senior editor at Zocalo Public Square, where this article first appeared. It is a project of the Centre for Social Cohesion at Arizona State University and a not-for-profit "ideas exchange" that blends live events and humanities journalism.