I've considered myself a liberal most of my adult life. As soon as I knew the difference, I have leaned left. Most of the stuff I see going on with the right wing of American politics is difficult to take, stomach or comprehend. The right wing assault on science, in the forms of creationism or climate change denial, is particularly alarming. But I find this far more alarming when the assault on science comes from the left. The idea that the progressive left is the friend to science is a myth. Many of them are as anti-science as the conservatives and an argument could be made that they have been more effective in squashing science because they do it from within (as teachers, bloggers or journalists) as opposed from above (politicians and businessmen).
1) Genetically Modified Foods (GMOs) are safe. Here in Vermont genetically modified foods have to be labeled even though there is no proof that they are dangerous in any way. Labeling it is harmless and, I guess, people have a right to know what is in their food, but many people assume that it must be bad if it is labeled. My friends on the left often refer to it as "franken-food," yet genetically modifying food has been going on for thousands of years by selective breeding. The strawberries you buy in the supermarket look and taste nothing like wild strawberries. Now that we do such selective breeding in a laboratory by altering plants on a genetic level, it is scary to some. It is a common trope among my liberal friends that anything natural is safe and mad-made is not, but there is no science behind this. Because GMOs are still reasonable new, research continues. If you don't eat them because you think that they need more research that is fair. But to outright claim that they are dangerous is pure conjecture and not science, and sometimes it is just paranoia.
2) Vaccines don't cause autism and are overwhelmingly safe. In all, vaccines have brought seven major human diseases under some degree of control: smallpox, diphtheria, tetanus, yellow fever, whopping cough, polio and measles. They have saved millions of lives. In 1998 a study was published in Great Britain that claimed a link between autism and vaccinations. It involved only 12 children and not only contained falsified data but severe conflicts of interest. It has been discredited and its main author lost his license, but this idea is still around and endorsed by some very famous people, most of them on the left. In 2017 already, ten states have reported measles outbreaks with over 60 deaths. The majority of the people affected were unvaccinated. The measles vaccine is not 100% effective, so some vaccinated will die if they are surrounded by the unvaccinated. Even as the evidence of vaccine safety piles up, so does the number of non-vaccinated. According to a number of articles I have read in the Washington Post and Mother Jones, this belief isn't higher among liberals but has broad belief across the political spectrum. I find this hard to believe. This week alone, I have had seen three of my friends on Facebook post something stupid about vaccines. So perhaps it is just me. I've never see any such thing from anyone that I'd consider conservative. Creationism and global warming denying yes, but my conservative friends have vaccinated all their children.
There was once a time in this country where the American university was a bastion of free speech. This time is over. When places like Middlebury College (here in Vermont) or UC Berkley erupt in violence over speakers visiting, we have to start asking the question: Is the left any better than the right? We used to be the adults in the room! You don't fight bad ideas by squashing speech. You fight bad ideas with good ideas. If there is bad science in Charles Murray's "The Bell Curve," you prove it with good science.
If you only listen to speech that you agree with, then you are just guilty of confirmation bias as an anti-vaxer or global warming denier that scours the Internet looking for articles that justifies their beliefs. Liberals are supposed to know better. Having an open mind means letting it all in (within reason), evaluating, culling ... embracing the good stuff and rejecting the bad ... repeat repeat repeat.