Pacifist: It is immoral to do anything that causes harm to another person. But, since using force causes harm to another person, it is also immoral to threaten to use force, even when such a threat is made in self-defense. Which one of the following principles, if valid, would most help to justify the pacifist's reasoning? ['Given the potential harm caused by the use of force, the line between use of force in self-defense and the aggressive use of force is always vague.', 'Whether a threat made in self-defense is immoral depends on the circumstances.', 'It is immoral to threaten to do what it is immoral to do.', 'It is immoral to carry out a threat if making the threat is itself immoral.']