Confidence is important in selecting your teachers, but a teacher who is over-confident and is so sure that his/her way is “the way” is probably the most dangerous of all especially when it comes to science. The saying that most medical students get when they enter medical school that “50% of what we will teach you is wrong, we just don’t know which 50%” still holds true and is even more correct as science progresses faster and faster which leads to more and more questions!
At some point, when you learn enough you realize that everything you thought was certain, just isn’t so certain, and is much more complex than you ever thought. One can even make the case that if you haven’t encountered this thought, you just haven’t learned enough on the topic you are talking about.
My teacher of blessed memory, Gerald Epstein, MD used to remind me that every time you open your mouth, you should ask yourself internally, “What do I myself, truly know about this topic?” as a reminder to be careful what you put into words. In the world of social media and edutainment, most content would probably disappear if this advice was followed 🙂