Socrates said that the hallmark of wisdom is knowing what you don't know.
Not knowing what you don't know causes big problems for the individual and the people in relations with that person.
Thinking that you know what you don't know is born out of insecurity and low self esteem and therefor the desire to opine and bloviate.
Thinking you know what you don't know is called, in psychology, the Dunning-Kruger effect. The Dunning-Kruger phenomenon is like a virus that can effect populations and can cause destructive consequences for that population. No better example of this Dunning-Kruger phenomenon in the United States currently is the contagion and death rate from the Covid-19 virus.
The United States is struggling with two viruses: Covid-19 and Dunning-Kruger. Public health experts and some government officials have issued public health guidelines about how to manage the Covid-19 virus, but there has been very little, if any, guidelines about how to manage the Dunning-Kruger virus; people who think they know when they don't.
Unitarian Universalists covenant together to affirm and promote the free and responsible search for truth and meaning. This principle refers to the human tendency to certainty when there is no validity or reliability to their beliefs. The practice of this principle requires humility and recognizing, acknowledging, and acting on an awareness of a lack of knowledge, knowing what one doesn't know.
The medical dictum is primum non nocere, "First do no harm." This is good advice for people who are inclined to manifest the Dunning Kruger effect.