A compass needle is light so it can turn easily. Hold your opinions light enough to turn when you learn something.

Usefulness depends on being able to move. A heavier needle would look more serious and be completely useless, since the entire job is responding to something true outside itself. What you think works the same way. An opinion welded in place stops being a method for finding north and becomes a thing you defend, and holding one lightly is not the same as having no commitments.

Take something you believe and find out who disagrees with it seriously, not the worst version of them. Read until you can state their case properly. Then keep your view or change it, and say which you did.