Lets say you have a colleague named Bob. Bob is a pretty good engineer, but he is as confident when he doesn’t know as when he knows.

You can never tell his degree of confidence in his answer. For low-level things he is pretty good but for critical high-level things it is more ambiguous.

You work around this by checking Bob’s work. Having formal verification steps to check what he says.

Now let’s say you meet Bob’s twin brother Bill. Who talks and sounds just like Bob. He makes fairly grand high-level statements that you can neither test nor verify.

How much do you intuitively distrust him?