There are two big types of errors people make.
One error is the assumption that you can and should know everything. For example, you discover a better way of doing something. “Why didn’t I know this before?” You get down on yourself and on life for not knowing everything ahead of time.
The other error is the assumption that you can’t know anything. “What do I know? Who am I to judge?” This kind of error not only undercuts self-respect and self-esteem; it also acts as kind of an excuse for not having to think and take responsibility for yourself.
You can’t know everything all the time. Yet it doesn’t follow from this that you can’t know anything.