Opinion is the medium between knowledge and ignorance.

Between not knowing and actually knowing there is a large populated middle where most of us live most of the time. Holding a view is not the same as being ignorant, and it is not the same as knowing either; it is a position taken on partial evidence, which is often the only kind available. The trouble starts when the middle state gets promoted to the top one in your own mind.

A habit worth building is saying which of the three you are in when you speak. I know this, I believe this, I have no idea. It costs nothing, and it makes you far easier to trust on the occasions when you say the first.