There is a problem if you regularly say “I don’t know” and there is a problem if you never say “I don’t know.”
Both are extremes. In the first case, it is a skills and competence issue and most of the time in the second case, it is an “ego” issue. I want to focus on the second case.
Many people have trouble being comfortable saying “I don’t know.” and it is more common amongst leaders than others. Sometimes leaders get carried away thinking that because they are the leaders, they are supposed to know answers for every problem that their people bring. They not only think that way – they think they should know the answer at that very instant. So, rather than accepting that they don’t know – they make up something. Most of the time, leaders are smart and they CAN make up things quickly and it may very well be something good. However, that is nothing like saying “I don’t know.”
Think about it – when you say “I don’t know” there is a whole new set of possibilities that will open up than when you start making up things. The moment you declare “I don’t know” the first thing that might come to your mind is to your mind is to ask for help. Help from someone that might know more about the topic than you. The other option you might look at is to start to learn more about the topic through books, tapes or websites related to that topic. In summary, you will be in a “learning” mode rather than “making up” mode. In the “making up” mode, you not only have the risk of “making up” a sub-standard solution to the issue at hand, you also have to start thinking about defending whatever you “made up.” It is like building a house of cards. If what you “made up” is not so good, you look bad not once but everytime you try to “defend” whatever you came up with in the first place.
If you think long and hard, you will see that “making up” is not worth it.
Lastly, saying “I don’t know” won’t make you small by any means. If in case, the team around you thinks that way, it is time for you to look at your team and see if it is the right team that you have assembled in the first place.