Editor's note: James Dawes, director of the Program in Human Rights at Macalester College in St. Paul, Minnesota, is the author of "Evil Men" (Harvard University Press). The opinions expressed in this commentary are solely those of the author.

(CNN) -- When most people look at ISIS, they see the incarnation of evil. Among its many horrific acts, the Islamic militant group beheaded American journalist James Foley and posted the video this week in retaliation for U.S. airstrikes in Iraq. The Pope typically protests violence, but he implied that he supports the use of military force to combat ISIS. Even al Qaeda says ISIS is too violent. Across the political spectrum, public officials and pundits have characterized them as "savages," a "cancer" and the "face of evil."

Is ISIS evil?

The problem with that question is that the answer is as easy as it is useless. Yes, ISIS is evil and must be stopped. Saying so over and over again could very well make it harder to stop them.

There is only one good reason to denounce a group as evil -- because you plan to injure them, and calling them evil makes it psychologically easier to do so. "Evil" is the most powerful word we have to prepare ourselves to kill other people comfortably.

The flip side is that "evil" is also a word that stops us from thinking.

There is no point in trying to understand evil because it is, in the most typical phrasing, "inhuman," "senseless" or "beyond comprehension." It is a fool's quest to analyze the local realities and strategic imperatives of unthinking savages. There is something almost offensive about trying to understand such evil.

National Review's Jonah Goldberg tried to shame those who are trying to think seriously about ISIS. In a recent tweet, he mocked the attempt to understand ISIS in its social and political context, suggesting that we should focus instead on one fact: "They're evil. They do obviously evil things for evil ends."

The fact is, there are few things more dangerous now than allowing ourselves to think that way.

To resist ISIS and, perhaps more importantly, the larger social forces it represents, the U.S. will need more than a collective psychological readiness to injure, and more than bombs.

The Wall Street Journal editorialized that this evil ideology will only be stopped when "enough of its fanatics have been killed." But if we've learned anything as a nation since our "shock and awe" campaign in Iraq, it is this: While invasions and bombing can be effective in the short term, they are not durable solutions to terror-based violence.

Even if U.S. military force could effectively destroy ISIS, there will be similar groups waiting in the wings. If we are to have any hope of preventing the spread of extremist ideologies, we must do more than bomb the believers. We must understand them. We must be willing to continue thinking.

How is ISIS able to achieve the support it needs? What drives people into its ranks? What social pressures and needs, what political and regional vacuums, make it possible for a group like this to thrive? We can choose to answer these questions in two ways.

We can say they are evil people doing evil things for evil ends. Or we can do the hard work of understanding the context that made them, so that we can create a context that unmakes them.

We can analyze the ways its violent tactics are effective for its purposes given the local power dynamics, so that we can also better understand its weak spots. And we can ask how it is that normal men -- men who were not born evil -- get turned into monsters, so that we can work to change the structures that produce terrorists over the long term instead of locking ourselves into an endlessly repeated, short-term policy of "killing fanatics" until they are gone.

Trying to understand something isn't the same as trying to justify or excuse it. That's a basic mistake, and a costly one.

As Jane Harman, president of the Woodrow International Center for Scholars, recently wrote: "We can't counter radical narratives if we don't understand the motives of the radicalized."

Nonetheless, trying to understand evil is an offense. It is an offense to everything we hold dear, because understanding -- that is, true and effective understanding -- must bring us close to the other, must help us see the world through their eyes.

That is a painful, offensive process, and that is exactly what we must do.

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