The Power of Not Knowing
It must be baked into our DNA to need to know something about everything. How many times are you having a conversation with someone and they simply say, "I don't know"? It doesn't happen very often, but I think it's one of the most important attributes a person can have. Too often people try to interject their opinions on subjects they know little to nothing about.
When I used to interview technical candidates, my goal was to see if I could get them to admit that they didn't know something. I would ask questions that they clearly did not know the answer to, yet they seemingly had answers that I can only imagine were coming to them in that moment. I'm sure they thought that they needed to know everything to get the job, but the truth is that no one can know everything. Having the humility to admit your ignorance is a quality that is especially crucial for consultants. The moment the customer realizes that you're BSing them is the moment you lose credibility with them. It's always better to admit that you don't know and that you will figure it out and get back to them.
There's power in not knowing. When you admit to someone that has more knowledge on a subject than you that you don't know something, you instantly gain credibility with them, and more than likely, they'll enjoy teaching you about the subject since they know that you are open to listening.
I'm by no means suggesting that it is ok to be gleefully ignorant on all matters. You should know a great deal about your domain, but you also need to know what you don't know. Besides, no one likes a know it all.