About Right and Wrong SnippetZero

The argument that it would be wrong is supposed to give him a reson not to do it. But if someone just does not care about other people, what reason does he have to refrain from doing any of the things usually thought to be wrong, if he can get away with it: waht reason does he have not to kill, steal, lie, or hurt others? If he can get what he wants by doing such things, why shouldn't he? And if there is no reason why he shouldn't, in what sence is wrong.

Because if you admit that you would resent it if someone else did to you what you are now doing to him, you are admitting that you think he would have a reason not to do it to you. And if you admit that, you have to consider what that reason is. It couldn't be just that it's you that he's hurting, of all the people in the world. There is no special reason for him not to steal your umbrella, as opposed to anyone else's. There is nothing so special about. Whatever the reason is, it's a reason he would against hurting anyone else in the same way. And it's a reason anyone else would have too, in a similar situation, against hurting you or anyone else.

But if it is a reason anyone would have not to hurt anyone else in this way, then it's a reason you have not to hurt someone else in this way (since anyone means everyone). Therefore, it's a reason not to steal the other person's unbrella now.