The left likes to pride itself as being firmly on the side of science, scoffing at conservative questioning of climate change, pollution, and evolution. But while Liberals are certainly au fait with evolution, they’re far less accepting of the evidence when it challenges their own ideology.

In areas where left-wing opinions contradict scientific evidence, there’s an unfortunate tendency to suggest that such scientific research is morally problematic. This speaks to a common trope on the left: their views aren’t simply accurate, but moral. Though those on the left are quick to point to right-wing scientific illiteracy, they’re often steadfast in their refusal to recognize their own dogma.

I saw this play out recently after reporting on the widespread myth that chemical imbalances cause depression. Thanks to a dearth of credible evidence, psychiatrists no longer ascribe to this theory. Scientists know both biological and social factors contribute to depression; they simply don’t yet know exactly which biological conditions create depressive symptoms. Similarly, though antidepressants are a huge help to many with mental health challenges, we don’t know precisely how the drugs work.

None of this is controversial from a scientific perspective, and was substantiated by eminent psychiatrists and peer-reviewed research. Yet, after we published, many on social media reacted with confident assertions that the story was false. Some suggested that debunking the chemical-imbalance myth of depression was akin to saying depression isn’t “real.”

My article, however, fully supported the conclusion that mental illnesses are undeniable and hugely harmful health conditions. And it did not say we should ignore the value of medication or stop investigating the biological causes of depression. Rather, it argued that though antidepressants do affect brain chemicals, a “chemical imbalance” in the brain is not the cause of depression. Further, an excessive focus on the biological explanation has led the scientific community to largely overlook the social causes of mental illness.

A few commenters confidently asserted that this argument would contribute to stigma around mental health. The false narratives around chemical imbalances have become closely intertwined with this admirable goal, as they’re used to suggest depression is a purely biological, physical disease, and so the impacts of mental illnesses are as undeniable as bodily ailments. But many illnesses are affected and treated by both biology and social conditions—diet and exercise are used to prevent heart attacks, while cancer risks are heightened by lifestyle factors like smoking and sunbeds—and are no less real for it.

And the evidence suggests that emphasizing the biological causes of depression is a misguided approach to improving the perception and understanding of mental health: study after study has found that explanations for causes of mental illness that focus on biology, rather than social factors, in fact increase stigma. When people believe someone’s biology makes them inherently unwell, they often perceive that person as dangerous and unpredictable.

Mental health is not the only sphere of unscientific leftwing dogma. There’s also considerable resistance, for example, to findings that genes significantly predict educational achievement and account for around 50% of personality. “The left-wing view is that everyone’s born the same and you can make everyone achieve the same way. From genetics research, we’ve shown that’s not true,” Saskia Selzam, a behavioral genetics researcher at King’s College-London, told me in 2016. Environment, of course, also has a huge effect on both achievement and personality, and this research shouldn’t be used to discount equal opportunity—indeed, researchers believe that understanding biological influences can engender more equality.

If we know a child has a genetic risk for dyslexia, for example, it’s possible to address that disposition early on through environmental factors such as tutoring and individual support. That can eliminate the psychological distress often caused by undiagnosed dyslexia and reduce the the severity of the condition. Children who aren’t diagnosed at an early age are typically placed in classes where the teaching doesn’t account for their dyslexia, and so have a much harder time at school as a result.

Similarly, scientists studying the biological factors behind gender difference say they face considerable pushback, often with political overtones. “Many people are uncomfortable with the idea that gender is not purely a social construct—and therefore malleable,” says Brenda Todd, a senior lecturer in psychology at City University London. “In reality, I believe that gendered behavior results from an interplay between biological predispositions and social influences.” This sort of research doesn’t argue that biology dictates a strict gender binary; it rather suggests both biology and society influence what is inevitably a wide spectrum of gender identity.

Another example of the dangers of left-wing dogma is the implicit association test. This test, meant to evaluate implicit biases, has been the subject of countless glowing articles and championed by well-meaning academics and HR departments hoping to rid the world of prejudice. It’s based on the premise that unconscious prejudices cause many people to act in an inadvertently biased manner and has been widely embraced by progressives hoping to combat discrimination. The test is a staple of diversity programs at Google, Facebook, and countless other companies, and is used by police departments across the US to change attitudes among members of their forces. But the enthusiasm for implicit bias relied too heavily on left-wing politics, rather than good science: it has repeatedly failed to meet basic scientific standards.

Fervent belief in the test among progressives has potentially undermined attempts to decrease discrimination. For example, under Eric Holder, an outspoken progressive attorney general, the US Department of Justice responded to incidents of racist police shootings by developing an implicit bias-based program to address discriminatory behavior “where actual racism is not present.” And implicit bias training has allowed companies to suggest (and even believe) they’re tackling diversity issues, while failing to implement practices such as equal pay and parental leave, or careful recruitment practices, that would make a substantive difference.

Some other antiscientific views are surprisingly politically bipartisan. Skepticism about the value of vaccines and the belief that genetically modified foods are harmful—both views strongly rejected by scientists—are equally common across the political spectrum.

It’s all too convenient to ignore or reject scientific findings that question deeply-felt political beliefs. But attempting to advance political ideals is no excuse for this bullheaded tendency, and those doing so can hurt the progressive values they seek to promote.

It’s easy to forget that the tools used to promote ideals shift. In the 1970s, the political left thought it was progressive to treat mental health in the US by combating social issues such as poverty and racial discrimination. The right-wing backlash to that approach made it seem too liberal, politically partisan, and inexpedient. So the left shifted, and began to frame mental health as a biological problem, rejecting the environmental focus as potentially stigmatizing.

Ultimately, US progressives—both today and in the 1970s—share the goal of improving mental health treatments. Acknowledging the evidence—even if it means adjusting a few key beliefs, such as the role of chemical imbalances in causing depression—can and should be used to inform and advance these sorts of progressive ideals. To truly be pro-science, those on the left can’t ignore the facts that don’t serve their political ends. Embracing science means acknowledging the evidence even when it goes against accepted dogma.