Develop credibility, humility, and a love of learning using a simple phrase

In the modern economy, expertise, skills and knowledge are some of the best measures of your competence. Many of us are afraid to admit whenever there's something we don't know. Despite that, one of the most important skills we need in the age of information is the ability to say "I don't know" both to ourselves and to others.

First, being able to admit that you don't know something forces you to stay humble. Being honest with yourself and others by saying "I don't know" means that you don't overstate your area(s) of expertise. This prevents you from receiving false recognition, which prevents arrogance and over-inflation of the ego.

Being able to say "I don't know" also keeps you curious and ready to learn. I'm not sure how most people are, but personally, if I'm asked a question and I don't know the answer, it bothers me. I want to find out the answer and look it up. That kind of behaviour develops curiosity and a love for learning new things. All because I admitted to myself and whoever is asking me a question that I don't know the answer.

Most importantly, in the long term, saying "I don't know" will keep you from losing credibility. There's always pressure to be a "subject matter expert", as well as the pressure to provide immediate answers without knowing what you're talking about. What will likely happen in this situation is that you'll give inaccurate information.  The person who receives that inaccurate information will make decisions, act on that information, and suffer the consequences.  When they do, you'll be blamed for their failure and be thought of as unreliable or worse, a liar.

Yes, it's important to be knowledgeable and skilled.  It's important to be able to answer questions about your field of expertise.  This is what competence in any field looks like. However, no matter how competent you are, there will always be something that you won't know. And that's all right. We're now in a world where almost all of human knowledge can be accessed almost instantaneously using a device in your pocket. You're better off saying "I don't know. I'll give you an answer as soon as I find out."