Why saying I don't know is a key to success - Poker champion Annie Duke
We have to embrace uncertainty. We have been taught that "I don't know" as a bad state of mind. But in most case it is an accurate model of the world. The more accurate our maps are, the better our decision making.
Beliefs are bets on the future.
If we have a certainty of belief, we will automatically dismiss opposing ideas(Motivated Reasoning/Confirmation Bias). Its better to have a belief that you are X% sure is true. If there is new information that affirms your belief, you increase your number. If you find evidence against the belief, you decrease the number.
If we don't have a certainty of belief, we'll be more likely to search for more information or help. If we are certain, we will not search further.