Some who easily change beliefs have little willingness to stand up for those beliefs. They change beliefs with social pressure and feel good fads more than ethical evidence. In other words, they act wishy-washy not because they are guided by good evidence, but because they are easy to trick with rotten ideas.
Others care little about ethical beliefs, except trudging forward or backward with their own egoism, hedonism or selflessness. Just do it might be their motto.
Still others, pretend. They say, "Bro, do you even science?" But they wall off most of the moral universe to good reasoning. They think of themselves as scientific, philosophical, and open minded, but in practice, they use intuitions on moral issues, often reserving good reasoning for self-interest or the natural sciences. Albert Einstein was a paradigm case of this type.
Many unconsciously anchor with what they heard first or float with what they hear often.
Then we have those with minds even more closed to ethical reasoning. They will fight hard for whatever horrible ideas they have. They are also easy to manipulate, but once they choose a belief system, or more specifically, a team, they will fight like hell for the team. In tribes, they team up for life, unless they are sold, bartered or kidnapped. Evidence on individual issues seems irrelevant to them. Team beliefs on an issue matter more. That's why Trump was loudly booed for saying there were no weapons of mass destruction in Iraq (unless we define Islam, endogamy, and demography as weapons.) Trump's claim violated still existing team beliefs. And that team is no fan of Trump's team. Some switch teams for ideological reasons--David Brock and P.J. O'Rourke, for example--but devotion to a team often remains.
In tribes, even the most preposterous superstitions manage to survive.
The old witticism about a liberal being so tolerant that he will not take his own side in a fight now seems like a sick, cruel joke.
The fanaticism of establishments is so great that even societal or personal ruin might not change their beliefs. They attribute ruin to their political enemies and anything but their own egoism, militarism, and multiculturalism, no matter how overwhelming the evidence. Every Western city could be in ashes, and they would still chant the R word as the main cause.
The fact that contemporary mass media are able to create such fanaticism, combined with so much glitz, is both creepy and horrifying.
The above is neither an exhaustive nor non-overlapping list of tendencies. Some individuals move from one tendency to another. Many other tendencies exist, especially policing the boundaries of acceptable myths, keeping out unwanted facts with straw person and ad hominem attacks, plus searching for reasons to feel morally superior to others, without having to make any sacrifices oneself.
We could write thousands of books describing logical fallacies, psychological errors, and ethical wrongs.
But I will eat a roll of paper towels if anyone can show me an establishment donor, thinker or politician who gathers and accurately weighs the good points from various sides.
How do we teach and eugenically build better humans out of that mess? Contemporary logic and ethics textbooks are atrocious. Today's parents and thought leaders likely dysgenically engineer children to be worse.
But improving reasoning is even more important than increasing intelligence.