The philosopher John Rawls argued that complete fairness can only come from hypothetical people in the "original position", in which they don't know who they will be in the real world. People with total memory loss about who they are, or dead people who are about to be reincarnated. Let these people sort out the issues of class, race, and gender. A poor person will be inclined to be for free schools and extensive social security, while a rich person will be inclined to refuse to pay such taxes since he can fend for himself and his own children anyway. But what about a person who doesn't know if he's rich or poor? That person would be more neutral and have a greater chance to form an unbiased opinion. And while such a person doesn't exist, we can consider what kind of opinion they would have if they did exist. While a Science Fiction story might actually give a character such a useful amnesia, more mundane usages of the principle are far more common - and usually far less Author Tracty. So, Bob is not unbiased, although he might believe he is. In either case, his bias can be turned against him! And thus, he might open up for someone to pull an Original Position Gambit on him, or even be deluded enough to pull one on himself. A villain pulling a full-scale Original Position Gambit will exploit his bias to the fullest, making him make value judgements and accept their rules based on his current position and then make him stand for his statements when he is in a very different position - one that they planned for him all along.