We all have a physical blind spot where the optic nerve joins the eyeball. Our brain plays a trick on us, filling in the spot with what it thinks should be there. We don't notice this unless we intentionally try to find it. You can find an example here.
What is funny about our other blind spots in life is we don't see them but have an uncanny ability to notice others. This bias is probably as old as time. We notice people's weaknesses, missteps, and misrepresentations of reality. Then, we share these "faults" with our friends and spin a shared narrative that only confirms our own beliefs. We search for our own "rightness" and join hands with others who share the same thinking line to affirm ourselves.
Is it possible that we don't have blind spots? It is unlikely. It is more probable that we don't want to recognize our blind spots. Some blind spots are in place to protect some deep core belief system tied to our identity. Have you ever heard someone explain something with logic that contradicted itself? As you read this sentence, I am sure a person or several people came to mind. Were they a close family member, a coworker, or your significant other? Yes, yes, and yes.
If it is so obvious for you to see this in others, could it also be possible that your blind spots are just as apparent for others? Unfortunately, the answer to this is also yes. So what should be done about this? Understanding is the first step, and the next is stepping outside your confirmation bias. Not everyone thinks the way you do are or has the same beliefs. A more accurate saying is that no one has your specific thoughts or beliefs. The more often you find a confirming voice to back up your beliefs (either your internal voice or a friend), the bigger your blind spots can become. This is a recipe for greater confidence and greater blindness.
One methodology that helps people understand themselves and others is the Johari window. It was developed by a guy named Joseph and a guy named Harrington. They combined their names and devised a simple and profound way to view ourselves. To do this exercise, a person uses a list of adjectives to describe their personality. Then they have peers describe their personality. Then the lists of adjectives are placed in the four quadrants below.
The two primary goals of this exercise are to improve friendships by shrinking the facade and gaining more knowledge of oneself by shrinking the blind spot and increasing the "arena" or "open" area.
Is it possible to be overly confident and blind? Yes. There is only one antidote to eliminate blindness: actively looking for blind spots. It takes courage to ask trusted friends about your blind spot. Recently I had someone reach ask me what they should keep doing, what they should stop doing, and what they should start doing. These simple questions impressed me because I am more of a mentee, yet he sought my opinion. I was impressed and inspired to take similar actions and see if I could shrink my blind spot. Humility here I come.