What is a dumb question..?

Ok first of all I don’t believe there are any dumb questions.. Its only dumb people. No questions are dumb. But people who don’t question are really dumb.
As a project Manager /Scrum master you need your team members to ask questions. You need your product owner /customer to ask questions.. you need your senior management and other stakeholders to ask you questions. If they don’t question and if they don’t ask questions freely , the payback you have will be too much for you to handle at the end of the project.
So how do you get people around you to question you ..? Its very simple... Create that environment around the project. Make it a project culture.. Every team member should be able to question about each other and about the product.. and about the requirements.
To my surprise I have come across with many project managers who create a shield to prevent others questioning about the project by being defensive for questions. This is really a bad syndrome. They have no idea how others around them could really help them to get them on line. Early awareness about issues to the management and to the customer really help to find solutions before its too late.
I still cant understand why a project manger cannot show his or her application design to a business manager.. and questions such as .. by looking at from the outside , do you think that this is user friendly enough ? Do you see any risks in this schedule which I have not seen so far.. its really important for a project managers to create this situation in any project. We all know scrum facilitate this situation. But unfortunately all the projects under the sun are not proper scrum projects. So no matter what the methodologies you use or technologies you use, it’s totally up to you to create enough transparency about your projects to encourage questions.