Generally, people know more than they think but unfortunately we too often fall into the trap of “I don’t know everything, so I don’t know anything.”
We run a seeing activity in our workshops where first individuals, then the group describe an image. When the group comments fade out I might say, did anyone see the flag, and it turns out many people would have seen the flag, but they were not saying it. Part of being a leader is helping people understand what they see and know, and helping them contribute to the group discussion.
Another strategy is when someone makes a judgment such as “the group was professional” we might ask them to describe what they saw or hear that caused them to say the group was professional.
On board the nuclear-powered submarine USS Santa Fe I would do seeing activities with my junior officers. We’d walk through a small compartment and then ask them what they saw. Turns out that seeing, like a golf swing, is a skill that can be practiced and improved.
So, the next time someone on your teams says “I don’t know” ask them to tell you what they do know.