In Patrick Lencioni's book The Five Temptations of a CEO (which is a great one, by the way), he warns business leaders to never confuse clarity with certainty. There are always things that are uncertain. Facts that require validation. Assumptions that need to be checked out. Assumptions that must be researched.

That uncertainty can't stop people from being clear in their communications. Better to say "here is what I know and here is what I don't know" and "here is what we are going to do," than say "I think we should do this." It is important in all of our communications that we model clarity, even if there are things about which we are uncertain. Better yet, if you feel like you can't be clear or certain in your communications, stop and take action immediately to resolve the issue. Once you find the answer or have taken appropriate action, then respond.

Note: sometimes this approach will require you to respond with a "I have heard you and will respond when I have a chance to give it proper attention". Especially if the request came via email, where people expect responses.

If you want to purchase a copy of Patrick's book--which is an easy, but insightful read-- click below.
The Five Temptations of a CEO: A Leadership Fable