Von Hippel offers two pieces of wisdom regarding self-deception: “My Machiavellian advice is this is a tool that works,” he says. “If you need to convince somebody of something, if your career or social success depends on persuasion, then the first person who needs to be [convinced] is yourself.” On the defensive side, he says, whenever anyone tries to convince you of something, think about what might be motivating that person. Even if he is not lying to you, he may be deceiving both you and himself.