Mayor Bill de Blasio has made “implicit-bias training” a major initiative of his administration. Based on the principle that, as he says, “we as human beings all come with biases that we have to overcome,” the training is meant to counterprogram racist responses supposedly wired into our brains. It has already been rolled out for tens of thousands of municipal employees across the NYPD and the Department of Education.

Since the firing of Officer Daniel Pantaleo, the mayor has stressed the extent to which the training has transformed the NYPD. In five interviews the day Pantaleo was fired, de Blasio cited this training as central to changes within the department. Its national implementation, he suggested, “can end this horrible history that’s holding us back” and “bring police and community closer together.”

The training’s substantive content, however, indoctrinates officers in a pattern of response that contradicts common sense.

The NYPD has assigned a multimillion-dollar contract to Fair & Impartial Policing, a Florida-based consultancy. The firm explains that its training is “about how the mind works,” and that “implicit biases can impact well-intentioned individuals outside their conscious awareness.” By exposing subjects to “counter-stereotyping,” it is possible to “override . . . discrimination-promoting . . . biases.”

The science behind implicit bias is weak. Based on response-time studies known as implicit-association tests, the theory isn’t replicable and doesn’t predict real-world discrimination. Even the IAT’s developers concede that it can’t measure or predict prejudice or racist behavior.

Plus, the theory doesn’t satisfy the “falsifiability” standard of scientific claims, insofar as it is semantically impossible to deny the idea that beliefs hidden below the level of consciousness drive behavior — any opposition can be interpreted as defensiveness.

Translating the theory into a classroom setting has predictably absurd results. Two NYPD officers who underwent the training describe an eight-hour seminar based on a PowerPoint presentation. “It was basically a formality, pretty dry,” said an officer with more than a decade of patrol experience. “Worst training I have ever had,” reports a sergeant with 15 years on the job.

The officers said that the lecture consisted largely of discussions about stereotypes they might harbor about people they encounter. Buck Angel, a transgender porn star whose hypermasculine presentation belies his female genitalia, was cited to demonstrate that appearances can be deceiving.

These examples are trivial, but more serious was a video of a middle-aged white man who murdered an unsuspecting policeman with a carbine during a routine traffic stop. The effective lesson the trainers imparted, according to the NYPD officer, was “to treat everyone like they are going to kill you.”

Indeed, Fair & Impartial Policing training materials contend that “implicit bias might lead an officer to be consistently ‘over-vigilant’ with males and low-income individuals and ‘under-vigilant’ with female subjects or people of means.” The premise is that an officer should approach everyone with the same assumption of threat level.

But police develop instincts about how to do their jobs based on long experience. “If I see an old lady crossing the street,” says an NYPD sergeant, “I will have a different expectation than if I see a tinted-out Nissan Maxima with Pennsylvania plates driving around a high-crime area at midnight.”

And the emphasis on applying equal vigilance to all encounters, one supposes, could encourage “hypervigilance,” itself the subject of special police training, implicated as a cause of excessive force as well as a primary source of mental strain and burnout for cops. While hyper-vigilance sounds positive in the context of public safety, experts in police training have warned against it for decades.

The sense that one’s life is in constant danger is associated with PTSD, panic disorder, reflexive shooting and even suicide. The recent spate of NYPD suicides has prompted the department to order all officers to undergo a one-hour online “Shield of Resilience” suicide-prevention course.

The course, designed by the federal Substance Abuse and Mental Health Services Administration, focuses on stress management, and specifically cautions against hypervigilance, explaining that “hypervigilance is defined as being constantly tense and on-guard; this can lead to serious health problems.”

De Blasio has promoted intrinsic-bias training because it allows him to promote the progressive idea that racism explains most of what is wrong in American society. But the misguided theory may be making cops’ jobs even harder than they are.

Seth Barron is associate editor of City Journal, from which this column was adapted.