Well...that is liberalism is in a nutshell. It is incapable of backing its many tenants with truth and fact. It is a fairy tale, but many fall for its silliness.
We conservatives know that political correctness, multiculturalism, moral relativism, appeasement, abortion, class warfare, welfare, big government, high taxation, ever increasing regulations, authoritarianism, cronyism, environmentalism, secularism, intolerance of Christianity.....and all the other evils that make up liberalism...WILL NOT WORK!
And, I believe that many of the Left elite know this. This is why they must dumb down America and flood us with lies and mis-information in the media, academia, p-schools, arts, Hollywood, etc....