1. Think about people’s believability in order to assess the likelihood that their opinions are good. 2. Remember that believable opinions are most likely to come from people 1) who have successfully accomplished the thing in question at least three times, and 2) who have great explanations of the cause-effect relationships that lead them to their conclusions. 3. If someone hasn’t done something but has a theory that seems logical and can be stress-tested, then by all means test it. 4. Don’t pay as much attention to people’s conclusions as to the reasoning that led them to their conclusions. 5. Inexperienced people can have great ideas too, sometimes far better ones than more experienced people. 6. Everyone should be up-front in expressing how confident they are in their thoughts.
Ray Dalio's Book Principles