The problem arises when pseudo-intellectual idiots get hold of something as beautiful and mysterious as quantum mechanics and try to pack humanism on to the back of the sleigh. Because the location of a subatomic particle can not be determined, right and wrong cannot be determined. Because a particle can be in two places at the same time, a person can be sane and insane at the same time. Because the state of a particle depends on the state of the observer, the meaning of "good" and "evil" depend on the cultural background of the person observing and describing these characteristics.
I think that liberalism (or perhaps I should say "humanism") is intensely jealous of the success of science, especially the science of the atomic age, the science of post-WWII western society. I believe that at least some strains of liberalism arose from intellectual poseurs who attempted to transpose the successful concepts of the hard sciences, physics in particular, onto moral philosophy and ethics. Much foolishness was the result and, to the extent that this foolishness has made it out of the effite precincts of academe and into the public square, in the form of laws and institutions, a cataract of pain, suffering, and injustice has been loosed on the world.
One day, Werner Heisenberg was pulled over for speeding. The Police officer asked him: “Do you know how fast you were going?”
Werner replied: “No, but I knew exactly where I was.”
In a similar vein, some insist that 'Santa Claus can materialize out of the vaccuum' and 'pterosaurs can suddenly poof into existence and snatch your kids away' are implications of quantum mechanics.