It’s Friday morning, so time to take issue with two common beliefs:
1. “The whole problem with the world is that fools and fanatics are always so certain of themselves, and wise people so full of doubts.”

In fact, numerous studies have shown that all people, including the wisest people in the land, tend to overestimate their abilities. You can see this in economic forecasters’ statements (see the financial crash and the post-Brexit-vote recession that was predicted to have started by now), journalists’ predictions (see Trump’s election, Cameron’s majority, Brexit), and politicians’ understanding of the world (both Cameron and Farage said that remain would win easily for example).
These are some of the most intelligent people in the land and they frequently get things wrong. A more accurate version of the above quote would be:
“The whole problem with the world is that fools and fanatics are always so certain of themselves, and so are (comparatively) wise people, who are also frequently wrong, and some of whom have more exposure.”

Studies to back this up:
Cognitive Sophistication Does Not Attenuate the Bias Blind Spot
The Trouble with Overconfidence
Overconfidence in case-study judgements
2. “Liberals are knowledgable, conservatives are ignorant”
When liberals and conservatives were asked what one another thought on different issues, liberals were worse at predicting what conservatives thought than vice-versa. People with more extreme positions on both sides tended to be less accurate than those closer to the centre.

In fact, liberals frequently fail to understand the moral basis of the positions of conservatives altogether.
Conservative MPs are bad at predicting the chance of tossing two heads if you toss a coin twice, but Labour MPs are considerably worse.

This does not mean that liberal ideas are necessarily wrong or that conservative ideas are necessarily right, of course, and this does not mean that conservatives know more about public policy-relevant issues. But it means that (when it comes to understanding the morality of the other side at least) one should not assume that someone is smarter or better informed because they call themselves a “liberal”.