Are you saying that people can lie about what they’re thinking?
That’s just one, most trivial fragment.
What I am saying covers more.
First, it is not just about thoughts, but also about character traits, competences, beliefs and the like.
Second, it is not just that people can lie to others, but also that they can be mistaken. Or they can be “in denial”, deceiving themselves, when they find the lie much more pleasant than the truth.
One variant of this is known as “Dunning-Kruger effect”. But there are many variants. For example, when a student who gets a failing grade on a quiz complains that he was studying hard, but, in fact, what he counts as “studying hard” is what professor would count as “hardly studying” (and, as the results of quiz show, professor is right).
And such cases are far more dangerous than mere lying to others.
Which is precisely why I am strongly against just assuming that someone knows what he is talking about, has looked at the evidence honestly and thoroughly etc.
For, well, what if you didn’t?
What if you just skimmed the text, not even noticing some of the words?
Would you have noticed that? Would you admit that to yourself?
After all, you have a clear conflict of interest: it is far more pleasant to think you did a good job, know what you are talking about, look at evidence honestly, are good at working with evidence, are “a good person” etc.
And thus it is very suspicious when such claims are not supported independently.
And I would strongly recommend you to be very careful here. Look for at least some independent confirmation. There are many such techniques for various things, like listing all the steps in argument explicitly and checking if each of them follows, using a checklist (like the ones made for examination of conscience), various certifications, exams.
