It seems that a ubiquitous theme of liberals is that liberalism is the ideology of evidence and reason, and conservatism is the ideology of evidence-denial and blind faith.
There’s only one thing wrong with that theme. The evidence.
Jonathan Haidt’s book, The Righteous Mind: Why Good People Are Divided by Politics and Religion is an overview of the current state of the art of knowledge that the social sciences, including Haidt’s own work, have amassed since David Hume said in 1739 that “Reason is, and ought only to be, the slave of the passions, and can never pretend to any other office but to serve and obey them.” (He was right).
The evidence for much of what follows comes from Haidt’s book. I’ve added some links to other sources.
If evidence were the sole driver of ideology then liberalism as we currently know it would not, could not exist. The understanding of human nature upon which liberalism rests is refuted by evidence. See the list of false statements further below.
Evidence proves that reason is, and can only ever be, a post-hoc rationalization of intuitions already felt, and decisions already made. It also proves that humans are very good at seeing the tiniest of flaws in the reasoning of those with whom we disagree, and very bad at seeing the gaping holes in our own.
Knowing this, humans put in place the scientific method through which we test our ideas by subjecting them to the scrutiny of others. It is from this method, eventually, that knowledge emerges.
Current knowledge of human nature shows that we are the only species that evolved to form into large cooperative groups of individuals who are not related to one another. Morality is the mechanism through which we cooperate. Morality is defined as follows:
Moral systems are interlocking sets of values, virtues, norms, practices, identities, institutions, technologies, and evolved psychological mechanisms that work together to suppress or regulate self-interest and make cooperative societies possible. (The Righteous Mind: Why Good People Are Divided by Politics and Religion,” by Jonathan Haidt, p. 314)
The evolved psychological mechanisms of morality include at least the following: care/harm, fairness/cheating, liberty/oppression, loyalty/betrayal, authority/subversion, and sanctity/degradation.
Current knowledge of human nature shows the following statements to be false. The falsehood of many of these is shown in The Righteous Mind, for those with other sources I’ve added links: