Trust and truth are interesting things. We trust ourselves more than anyone else for the most part. Sometimes we trust others more than ourselves. So much so that some people will have a person that they tell secrets and ask advice on their life. They do have the choice to ignore advice however.
The idea that you know what you know so you can trust it sounds fairly reasonable. We can’t trust it when the information is faulty and that is when we ask someone for help. When we know that someone else is far better at something, we ask them for their decisions and what to do so that we may mirror their success.
When it comes to what others know or think, we can only know what they communicate to us through things like speech or body language. Even if we trust them because they have a long track record of not lying to us. People make decisions on what THEY want. Sometimes what they want is to do thing that YOU want. This means that if there are factors in the decision that override their loyalty to you.
It is impossible to have the same certainty of trust. The flavor of trust that is all about how probable is it that they would not purposely deceive you for their own personal reasons. We can trust that we, ourselves, would not purposely lie to yourself for some personal selfish reason. Especially if that reasoning ending with negative consequences such as injury, loss of a job, etc.
Many people do lie to themselves all the time. This is called cognitive dissonance. It is where two conflicting pieces of information are trying to be held at the same time. It creates a logical paradox because both things cannot exist as true at the same time. So a lie is created that explains why the two things can coexist.
Example: You are trying to reach a fruit hanging from a tree but you cannot reach the tree. You can say that the tree is too tall, or that you are short. So you say that you cannot reach the tree because it is too tall. The tree may not be too tall at all, and in fact, the person trying to reach the fruit may just be very short. Children might not say this because they don’t have that big of an ego yet usually. They say that they are not tall enough to reach it. Essentially saying they are short.
Example 2: A guy asks a girl to dance at a dance club. The girl says no. The guy insults the girl by telling her that she must be a lesbian if she didn’t want to dance with him. Because being something a girl doesn’t want, it must mean the girl has a problem that makes her not want the guy.
It is a lie we tell ourselves that makes the situation more friendly to ourselves. To face the lie may destroy the very foundation of the persons entire personality and life choices. Sometimes it just make them very sad and they already have issues with depression. There are various reasons why a person will lie to themselves.
This means that no matter what we do, we cannot ever be fully sure that we can trust anyone at all. In the end, we lie to ourselves as well.