This is why understanding logic is so crucial for figuring out who the liars are. A liar will always, always, be logically unsound and inconsistent (they're hypocrites and use logical fallacies). Unfortunately, there's quite a lot of good men who use logically unsound arguments and are logically inconsistent, but I attribute that mostly to the corruption and dumbing down of Western society. And, if a good man truly is good (meaning he prioritizes truth above all else, even his own ego), he should be capable of admitting wrong and correcting beliefs and arguments.