Abstract: The stress point of the contractualist ethics of Thomas Scanlon, who is one of most important contractualist ethicist, lies in essential characteristic of morality. To be answer the main question of moral theory is one of right or wrong of moral behaviors. T. Scanlon argue that one action is wrong, which can not be justified reasonable. Such kind of judgment is also the one by which people can not act by the way as well. The moral judgment generally depends on moral principles, However, principles can not totally decide the action of judgment in practice. It is necessity that we need some kind of Aristotle’s practical wisdom when we do it.

Key words: wrong in morality the reasonable principles and judgment