Psychopath. The word conjures up the image of a cold-blooded killer, or perhaps a fiendishly clever but heartless egoist. There’s Ted Bundy, who in the 1970s abducted women, killed them, and had sex with their decomposing bodies. Or Hannibal Lecter from the film The Silence of the Lambs (1991), who cunningly escaped his various confinements and ended up eating the people he despised. In the popular imagination, psychopaths are the incarnation of evil. However, for an increasing number of researchers, such people are ill, not evil – victims of their own deranged minds. So just what are psychopaths, and what is wrong with them?

According to the Hare Psychopathy Checklist – first devised in the 1970s by the Canadian criminal psychologist Robert Hare and since revised and widely used for diagnosis – psychopaths are selfish, glib and irresponsible. They have poor impulse control, are antisocial from a young age, and lack the ability to feel empathy, guilt and remorse. Psychopaths steal, lie and cheat, and have no respect for other people, social norms or the law. In some cases, they torture defenceless animals, assault other children or attempt to kill their siblings or parents. If caught, they fail to take responsibility for their actions, but tend to blame others, their upbringing or ‘the system’. According to some recent calculations, more than 90 per cent of male psychopaths in the United States are in prison, on parole or otherwise involved with the criminal justice system. Considering that psychopaths are thought to make up only around 1 per cent of the general population, that number is staggering. Because of this close link to criminality, psychopathy used to be known as ‘moral insanity’.

This picture of psychopathy has dominated the thinking of both laypeople and researchers. It’s at once sensational and reassuring. Psychopaths are sick, deranged, lacking in moral conscience. In other words, they’re nothing like you or me. But this is false. There’s no major ability that psychopaths lack altogether, and their deficits are often small and circumscribed. They certainly aren’t incapable of telling right from wrong, making good decisions or experiencing empathy for other people. Instead, they suffer from a host of more mundane problems – such as being overly goal-fixated, fearless and selfish. What’s more, perhaps ‘our’ reactions are closer to ‘theirs’ than we realise. Like psychopaths, we can dial our empathy up and down; and for all the praise we heap on empathy, a closer look at this emotion suggests that it’s nearer to a kind of self-preservation instinct than any ‘warm and fuzzy’ fellow-feeling.

Rather than freakish outliers then, psychopaths reveal important truths about human morality. But are we ready to accept what they might teach us?

When debating what’s wrong with psychopaths, researchers typically pitch two competing moral theories against one another. One approach, known as rationalism, holds that judging right and wrong is a matter of reason, rather than feeling. Some philosophers claim that psychopaths show that rationalism is plain wrong. Psychopaths are as logical as you and me – in fact, they outsmart us all the time, hence their everyday depiction as connivers and con artists. So the fact that they’re rational but still capable of inhuman acts shows that moral sensibility can’t be grounded in reason alone.

But something isn’t quite right here. If psychopaths are so smart, why do they constantly get caught up with the criminal justice system? In his authoritative portrait of psychopathy Without Conscience (1993), Hare describes a man who was on his way to a party when he decided to get a case of beer. Realising he’d forgotten his wallet, the man – who scored highly on Hare’s psychopathy checklist – robbed the nearest gas station, seriously injuring the sales attendant with a heavy piece of wood.

So while psychopaths aren’t irrational in the sense of being unable to think clearly, they seem to act irrationally. They struggle with what philosophers call ‘reasons for actions’: considerations that underlie our decisions to act, such as the likelihood that what we’ll do will satisfy our goals and won’t come into conflict with other projects or aims. Although bludgeoning the shop assistant does, for example, serve the goal of getting beer for the party, it frustrates the more pressing and underlying desire to stay out of prison. Psychopaths appear to be poor at integrating all the various factors that go into making good choices, and often have poor reasons for their actions.

The psychological evidence confirms that psychopaths have deficits in reasoning that affect how they make decisions. They usually attend almost exclusively to the task at hand (whatever that might be), and ignore relevant contextual information – although when context doesn’t play a role, they do very well. Other studies have found that psychopaths have problems reversing their responses: when actions that were previously rewarded are now punished – or actions that were previously punished are rewarded – they have problems adjusting. Similarly, Hare and his collaborator Jeffrey Jutai found that, if psychopaths are asked to navigate a maze, they doggedly pursue their initial tactic even if doing so causes them to receive painful electric shocks. Whereas most people desist and find other ways to navigate their way through, psychopaths tend not to. This insensitivity extends to social threats, such as angry faces.

These findings support the rationalist idea that psychopathic immorality comes down to some inability to reason well. But you might have noticed that psychopaths don’t experience fear as often, and in the same situations, as do ordinary people. Last time I looked, fear was an emotion. This brings us back into the camp of people who think that emotion, not reason, is central to ethics. Typically they focus on empathy.

When explicitly told to empathise with another, psychopaths could do it

Apart from some notable empathy naysayers, such as the psychologist Paul Bloom at Yale University and the philosopher Jesse Prinz at the City University of New York, empathy is typically held in high regard among theorists and researchers. Part of the reason is its excellent fit with a second major moral theory known as sentimentalism. Dating back to the 18th-century philosophers David Hume and Adam Smith, sentimentalists believe that an ability to tell right from wrong is grounded in a tendency to feel what others feel. Because we suffer along with others, we come to see their suffering as bad or wrong. Thanks to these empathic feelings, we care about what happens to other people even if it doesn’t directly affect us.

One of the best empirical sources for these claims is the social psychological research on empathic concern. Psychologists working in development, such as Martin Hoffman at New York University and Nancy Eisenberg at Arizona State University, maintain that it plays a central role in social competence and moral understanding. Dan Batson argues that empathic concern is a warm, soft-hearted, compassionate feeling for someone in need, which leads to truly altruistic behaviour. Empathy motivates us to treat others well, and it is at the foundation of moral regard for others. Psychopaths appear to validate these ideas, apparently lacking both moral sense and empathy.

However, psychopaths fare strangely well on tests of empathy. Given that these tests are usually based on self-reports and that psychopaths are prolific liars, this is not necessarily surprising. But psychopaths also produce intriguing results on experiments that test physiological and brain responses. Skin conductance, for example, measures how good a conductor of electricity your skin is; it’s a good indicator of your emotional state, since when you sweat in response to stress, fear or anger, your skin becomes momentarily better at carrying electric current. As you might expect, when psychopaths are exposed to pictures of people in distress, they show less skin conductance reactivity than do non-psychopaths. Other tests measure startle responses: if you show a person pictures that they find threatening, they startle much more easily in response to loud sounds. Psychopaths respond normally to direct threats, such as an image of the gaping jaw of a shark or a striking snake, but not to social threats, such as people in pain or distress. Ordinary people react to both.

Neuroscientists have also studied the empathic responses of psychopaths. In typical studies involving functional magnetic resonance imaging (fMRI), the areas of the brain associated with empathy don’t activate in psychopaths to the same degree as in control subjects. But when the neurobiologist Harma Meffert and colleagues from the University of Groningen in the Netherlands explicitly instructed them to ‘feel with’ a hand that is being caressed or shoved aside, the researchers discovered that psychopaths were able to muster a normal response. In other words, when explicitly told to empathise with another, psychopaths could do it.

The neuroscientist Jean Decety and colleagues at the University of Chicago unearthed something similar. He showed psychopaths pictures of limbs in painful situations, such as a hand stuck in a car door, and asked them to either ‘imagine this is happening to you’ or ‘imagine this is happening to someone else’. When psychopaths imagined that they were in the painful situation, they showed something very close to the typical empathic brain response – but when they imagined someone else was in that very same situation, their empathy-related brain areas didn’t activate much.

If psychopaths have an empathy deficit, then, it is a very puzzling one. A different way of measuring brain activation throws further light on the puzzle. Electroencephalograms (EEGs) measure brain activation over time, as opposed to fMRI studies, which produce measurements of brain activity at one particular moment. EEG studies with psychopaths are quite revealing: it turns out that their initial brain response to people in distress is largely intact. Psychologists call this the ‘orienting response’, which is the act of turning your attention to a stimulus – in this case, another person in trouble. This is associated with the sympathetic nervous system that mobilises a defence response. This first reaction appears to be entirely involuntary in psychopaths and non-psychopaths alike. It’s what happens in the later stages that is different: instead of their defensive response continuing to get stronger, and their attention becoming even more focused on the person in distress, the psychopaths’ response weakens and begins to die down. Why?

Other empathy studies offer hints. It turns out that doctors show something of the same response as psychopaths do when exposed to people being injected with needles. Since doctors are perfectly able to empathise with others when they need to, the thinking is that the reduced response must be due to the person herself exerting cognitive control over her emotions. Because they have to do things to patients that are unpleasant or even painful, doctors get used to it and suppress their normal empathic responses.

That explanation fits with what we know about the relationship between empathy and reward: studies have found that men improve their understanding of what others think and feel only when they are paid to get it right, while understanding others is reward enough for women. Leaving aside such thorny gender issues, we can conclude that people are able to modify their empathy according to punishment, habituation or reward. So perhaps we should think of empathy and psychopaths the same way: they dull their empathic response to others in pain, but they are not naturally insensitive to it.

This evidence forces us to rethink not only psychopathy, but also empathy and its role in moral aptitude. First of all, it’s a mistake to think of what is wrong with psychopaths in terms of lacking abilities. They’re neither unable to comprehend what it means to have a goal or an end, nor are they incapable of feeling empathy for others. They have deficient abilities, we might say, but these deficits are typically small and dependent on the context.

Similarly, on the empathic front, psychopaths aren’t total outliers – in fact, many people describe them as extremely charming and personable. Hare is one of the greatest experts on psychopaths, and in Without a Conscience he describes how he was conned by a psychopath, who invited him to give a paper at a conference. He was supposed to receive an honorarium and have his travel paid for, but never saw a penny. Although he spent a nice evening with the guy at the conference, he never suspected a thing. The larger point is that for psychopaths to be able to fool experts, and to be able to persuade people to do things they would not otherwise do, they can’t be emotionally stunted robots. The usual story is that they are good at faking it; but another, more plausible, explanation is that empathy can’t really be faked, and that psychopaths are simply better at turning their empathy on and off.

Psychopathy suggests that an important part of morality rests in our propensity to be personally distressed

What makes this account of psychopaths’ problems particularly interesting – but also subversive – is that they start to look a lot more like ordinary people. Take empathy with others in distress. An ordinary person goes to great lengths to avoid experiencing this emotion – by averting his gaze from the beggar on the street, or choosing another channel when news of conflict and disaster come on the TV. In some cases, it makes sense to protect oneself from the pain of others’ pain. We can’t possibly change the fates of all who suffer, no matter what we do. Then again, many of us could be more effective if we really tried. What can I personally do about the crisis in Syria? Probably more than I’m doing at the moment. Most of us don’t shy away from helping others because we can’t but because we’re unwilling to expend the time and resources that would be required. So psychopaths might not be so aberrant in their refusal to feel for those who suffer. Perhaps they are simply at an extreme end of a spectrum on which most of us find ourselves.

The second big fallout of the research on empathy in psychopaths is a profound rethinking of empathy itself. The empathic concern that most psychologists talk about sounds nothing like the aversive response to others in need that appears to be lacking in psychopaths. This aversion is better thought of as ‘personal distress’ – an unpleasant experience that can be described by words such as ‘grieved’, ‘alarmed’, ‘disturbed’, ‘upset’. It arises as a defensive reaction to others’ pain or fear – something we feel as much for ourselves as for the other, and that we try to avoid whenever we can. Most psychologists think that personal distress is contrary to morality. Why? Because it leads us to avoid the person in need. Turning this issue on its head, then, psychopathy suggests that an important part of morality rests in our propensity to be personally distressed. We are motivated not to harm others because witnessing pain and distress is distressing – for us.

The psychopath’s response to people who suffer indicates that what we recognise as morality might be grounded not simply in positive, prosocial emotions but also in negative, stressful and self-oriented ones. This is not some cuddly version of empathy, but a primitive aversive reaction that seemingly has little to do with our caring greatly for the humanity of others.

Yet what exposes our common humanity more than the fact that I become personally distressed by what happens to you? What could better make me grasp the importance of your suffering? The personal part of empathic distress might be central to my grasping what is so bad about harming you. Thinking about doing so fills me with alarm. Arguably, it’s more important that I curb my desire to harm others for personal gain than it is for me to help a person in need. Social psychology research has focused on how we’re moved to help others, but that’s led us to ignore important aspects of ethics. Psychopathy puts personal distress back in the centre of our understanding of the psychological underpinnings of morality.

The last lesson we can learn concerns whether sentimentalists or rationalists are right when it comes to interpretations of the moral deficits of psychopaths. The evidence supports both positions. We don’t have to choose – in fact, it would be silly for us to do so. Rationalist thinkers who believe that psychopaths reason poorly have zoomed in on how they don’t fear punishment as we do. That has consequences down the line in their decision making since, without appropriate fear, one can’t learn to act appropriately. But on the side of the sentimentalists, fear and anxiety are emotional responses. Their absence impairs our ability to make good decisions, and facilitates psychopathic violence.

Fear, then, straddles the divide between emotion and reason. It plays the dual role of constraining our decisions via our understanding the significance of suffering for others, and through our being motivated to avoid certain actions and situations. But it’s not clear whether the significance of fear will be palatable to moral philosophers. A response of distress and anxiety in the face of another’s pain is sharp, unpleasant and personal. It stands in sharp contrast to the common understanding of moral concern as warm, expansive and essentially other-directed. Psychopaths force us to confront a paradox at the heart of ethics: the fact that I care about what happens to you is based on the fact I care about what happens to me.