Being confidently wrong is louder than being quietly unsure. Don’t confuse the volume for the answer.

Certainty is easy to perform and doubt is not, so the loudest voice in a room is often the one with the least to lose by being wrong. People who genuinely know a subject tend to hedge, because they can see the places where it gets complicated. That hedging sounds weaker and is usually nearer the truth.

In your next group argument, notice who is saying how they know rather than only what they know. Ask the confident person where their information came from, politely. If nobody can answer that, treat the whole thing as unsettled for now.