How does the non-aggression principle relate to the impotence of evil?

How does the non-aggression principle relate to the impotence of evil?

What is "the non-aggression principle"? As far as I know, that expression does not appear anywhere in the literature of Objectivism, although there are a great many mentions of "aggression" by itself, as a generic concept, including expressions like "military aggression" or "foreign aggression" or "communist aggression," etc. A "non-aggression princple," attributed to Objectivism, probably refers to Objectivism's ban on the initiation of physical force against others.

The relation of evil to the ban on initiation of physical force against others is that initiation of physical force against others is evil. It is a major evil, in fact -- although evasion is also regarded as a major evil by Objectivism, and more fundamental, underlying all forms of evil.

The Objectivist principle of the impotence of evil is that evil is very powerful when good people allow it to extort power from them, and powerless when they don't. This is the Objectivist principle of "the sanction of the victim." If such sanction is withdrawn in its entirety, evil loses its power. Evil is fundamentally impotent; it gains power from those who are not fundamentally evil, but who endorse and support evil; it loses its power without those endorsers and supporters.

Is saying a situation is contextual also another form of saying something is subjective?

No. Objectivism recognizes that all knowledge is contextual. But this does not mean that it depends on anyone's own wishes, personal opinions, hopes or fears, either as individuals or as a "collective." Context is real; context is not inherently subjective.

...the situation in which physical force is used is contextual.

Yes, the retaliatory use of physical force against the initiation of physical force, and against those who initiate its use, depends on the context of a prior initiation of physical force. Even the initiation of physical force depends on the context of a victim against whom physical force is initiated.

...many prominent Objectivists support going into Iran. I also believe Iran is a threat to freedom and the world, and we should stop them.

As I understand it, the significance of Iran is its ideological role as the center of Islamic religion in the world today, the source of the ideology that fuels and sanctions terrorist attacks on Western countries. Militant Islam exhorts and incites such attacks. Retaliatory physical force against Islamic terrorist attacks therefore will be most potentially effective if directed against Iran, by destroying the "soul" of the terrorists and other Islamic states in the region who support and harbor the militant Islamic terrorists. I have also seen calls for similar action against Saudi Arabia, because of their role in providing financial support for militant Islamic terrorist attacks.

...this stance says something about what we think about the concept of evil. Philosophically, if we doing nothing for evil, it will fail.

The questioner needs to specify who "we" refers to. If it means the U.S., Iran does not gain its power entirely from the U.S. alone. Most of its power comes from many others around the globe and within Iran who sanction and support militant Islam. The U.S. is only one of the sanctioners. And make no mistake -- Iran is definitely evil and definitely powerful, insofar as it receives the sanction and support of others anywhere in the world who are not entirely evil, but who nevertheless give their sanction and support to Iran. Our current president is certainly a significant sanctioner of Islamic religion, but he is far from alone, and the whole U.S. is far from alone in this respect among the nations and societies in the world.

...if we do nothing for Iran, the regime still won't collapse.

If "we" means the U.S., the U.S. is far from alone among the nations and societies in the world in sanctioning and supporting the Islamic faith that Iran promotes, and evading the militancy toward reason and productive civilization that Islam implies.

Philosophically, if we doing nothing for evil, it will fail. This was the argument Ayn Rand made.

No. Ayn Rand's argument concerns what and who makes evil possible. She did not use the term "we" as a floating abstraction.

Obviously, if we have to step in against the Iranian regime, evil has some amount of vitality.

Of course it does. The point is who and what gives it whatever vitality it has. It's not just the U.S., nor even primarily the U.S., although support from the U.S., as the leader of the free world, is certainly a huge factor in the "sanction of the victim" as it relates to Iran.

While I understand and respect Ayn Rand's view on evil, I believe since that man has free will--making them unpredictable--good and evil are two equally powerful forces set against each other.

The greatest conflicts are between good and good -- good that opposes evil, and misguided "good" that sanctions and supports evil. That was Ayn Rand's view on evil, especially as concretized in Atlas Shrugged. A fully consistent drifter and evader is impotent and of little concern to one who focuses his mind and lives by reason. But if a chronic evader can persuade others to help him in his evil, others who far more often focus their minds and live by reason, then the primary evil-doer gains potency through them.

It should also be noted that the actual citizens in Iran will not stand up to their government. They tried a few years ago, but it didn't work. In fact, Obama didn't even side with the revolters....

He should have. It might have made a difference. The victims of Iranian theocracy can't do it alone, in the face of waffling, indecision and overt moral sanction of Islam from so many sources outside of Iran. They might have a better chance if it was just a case of the Iranian people against an Iraniam regime that receives no moral or material assistance beyond its own people.

One of the problems that our president faces, however, is that Islam is not the only form of religion that opposes reason and productive civilization. To oppose Islam consistently, one would have to oppose all religions. But Islam in the Middle East certainly tops the list at present among mongers of militancy. Other religions contain similarly militant implications, too, but tend to be less strident about it in the context of the Renaissance-Modern era of world history. Islam today is a throwback to the Christianity of the Medieval-Christian epoch in world history, which arose as the Greco-Roman era was declining.

It's not impotent.

The key is to recognize why -- to recognize all the ways that the otherwise "good" in the world sanctions and supports evil -- to recognize whether you are looking at pure, unaided evil, or evil that is supported by the good -- and to work to end the moral sanction of evil in any form by those who are fundamentally good in most of their outlook and actions -- to show them how it is only their sanction that makes evil potent.