Is Psychopathy
a Zombie Idea?

From moral derangement to social predator

Psychopathic personality disorder — or psychopathy as it is commonly called — is one of the oldest and most researched mental health diagnoses. The first account dates back to 1786, when the American physician Benjamin Rush described a mysterious condition he called moral derangement, suggesting that some individuals had lost the ability to distinguish between good and evil. Though highly speculative, this early description portrayed psychopathy as a biological disorder that impairs the innate human capacity for moral attitudes and prosocial behaviour.

In modern science, psychopaths are typically described with reference to symptoms such as a lack of empathy, remorse and conscience, as well as behavioural signs like predatory violence, pathological lying and impaired impulse control. The researcher Robert Hare famously characterised psychopaths as social predators who charm and manipulate others, leaving behind a trail of emotional and financial devastation. This dramatic portrayal has strongly influenced both scientific and popular understandings of the condition.

The psychopath has also become a figure of cultural fascination, often depicted in novels and films. One particularly jarring example is Anton Chigurh in No Country for Old Men (2007). Portrayed as emotionally vacant and morally empty, he embodies traits frequently associated with psychopathy, including emotional detachment and ruthless violence. Yet such fictional characters are not clinical case studies.

In fact, recent decades have been sobering. Numerous empirical studies have either thoroughly refuted earlier claims or failed to provide consistent support. Take empathy as an example. A common assumption is that psychopaths lack empathy. However, large-scale systematic reviews involving thousands of clinically assessed individuals have produced overwhelmingly null findings. In other words, statistical analyses often cannot distinguish between psychopathic and non-psychopathic individuals in empathy experiments. In behavioural science, where false positives are common, this degree of consistency is arguably close to proving a negative.

Similarly, the long-standing claim that psychopaths have shallow emotions has not held up under scrutiny. Early studies appeared to suggest abnormalities in physiological responses, but later research revealed that the evidence was vanishingly thin. In the vast majority of psychophysiological tests, no clear distinction can be made between diagnosed individuals and control groups.

Many claims about psychopathy follow the same trajectory: initial enthusiasm, followed by a torrent of studies that fail to replicate early results. Assertions that psychopaths are uniquely dangerous, genetically distinct, neurologically impaired, or resistant to therapy have repeatedly failed to withstand rigorous testing.

Why, then, does the idea persist? Two explanations are often offered. The first is that psychopathy may be too complex for current scientific tools to capture reliably. Researchers frequently cite methodological limitations rather than reconsidering the underlying concept. However, modern studies employ sophisticated neuroimaging and advanced statistical modelling. If psychopathy truly involved extreme deficiencies, they should have been detected by now.

A second explanation concerns measurement. Much research relies on the Psychopathy Checklist Revised (PCL-R). Critics argue that if this instrument is flawed, research findings will inevitably be distorted. Yet alternative tools have produced similar results, suggesting that the problem may lie deeper than methodology.

History offers examples such as phrenology or race theory — ideas that persisted long after being scientifically discredited. Supporters of psychopathy research sometimes cite infamous serial killers as obvious examples. However, closer examination often reveals complex psychological histories involving trauma, delusions, or substance misuse — profiles that do not neatly align with traditional descriptions of psychopathy.

Historically, psychopathy research has been far from unified. In the 1970s and 1980s, prominent scholars described it as a "white elephant", a "waste-basket diagnosis", or even a "mythical entity". Nevertheless, the 1990s saw a sudden surge of interest, possibly fuelled by cultural fascination and tough-on-crime politics rather than new empirical breakthroughs.

Today, after hundreds of studies, the aggregation of scientific evidence does not convincingly support the existence of psychopathy as originally conceived. Instead, the growing body of research increasingly throws the concept into doubt. If psychopathy is indeed a zombie idea, it may be time for science to finally lay it to rest.