I'm always ready to say I don't know. But just to advocate for the opposite -- it is perfectly OK to have an clear opinion, weakly held.

So, say what you think but at the same time ask (demand?) an argument or discussion.

A friend has a T-shirt with the words: Always sure, often wrong.

Also see: https://www.psychologytoday.com/us/blog/work-matters/201002/...