In past weeks, many have observed that those who flew planes into the World Trade Center had reasons for what they did: They disapproved of U.S. foreign policy, and they disapprove of our support of Israel in particular. For the purposes of debate, let us accept that these observers--including Sam Keen--are right, at least in their attribution of motives.

But discerning motives on the part of terrorists by no means exonerates them from the charge of evil-doing. Are we to believe that only those who act in a purposeless manner can legitimately be accused of evil? I think we can see how inappropriate, indeed silly, that would be. Many seem to be under the impression that only those who do bad things for no reason other than the fact that they are bad can be accused of evil-doing.

If so, these observers fail to understand the underlying concept of evil. As it has been understood by a wide range of theologians (such as St. Thomas Aquinas) and popular writers (such as C.S. Lewis), evil is not to be thought of as the opposite of good but as the perversion of good. Theologians are in agreement that there is no such thing as "pure evil." In denying that the terrorists manifested just this attribute, pundits are shielding them from a charge that they have themselves invented. Not just sometimes, but always, evil is done by those who aspire to some ultimate goal that is good. So we should not be surprised if the same applies to those who destroyed the World Trade Center.

Here is the relevant observation from C. S. Lewis's best-known book, Mere Christianity:

"In real life people are cruel for one of two reasons -- either because they are sadists, that is, because they have a sensual perversion which makes cruelty a cause of sensual pleasure to them; or else for the sake of something else that they are going to get out of it -- money or power or safety. But pleasure, money, power and safety are all, as far as they go, good things. The badness consists in pursuing them by the wrong method, or in the wrong way, or too much. I do not mean, of course, that the people who do this [commit cruel acts] are not desperately wicked. I do mean that wickedness, when you examine it, turns out to be the pursuit of some good in the wrong way.

"You can be good for the mere sake of goodness. You cannot be bad for the mere sake of badness. You can do a kind action when you are not feeling kind and when it gives you no pleasure, simply because kindness is right; but no one ever did a cruel action simply because cruelty is wrong. Badness cannot succeed in being bad in the same way in which goodness is good. Goodness is, so to speak, itself. Badness is only spoiled goodness."

So, too, the terrorists were no doubt pursuing some ultimate "good," as they saw it (autonomy for the Muslim world, for example), but they were also most decidedly pursuing it "in the wrong way" (by murdering innocent people). Our natural inclination to call the terrorist attacks evil is therefore sound from any reasoned moral or theological perspective. In pursuing a goal that may well have been good in itself, the recent acts of terrorism were no different from other evil acts, except that they were far more heinous than most such acts.

Some people have difficulty with this analysis of evil, I believe, because we have so much fallen out of the habit of thinking in terms of evil at all. Routinely, we fear that anything we say might "give offense." We worry about being too "judgmental." Our relativized understanding of truth has taken its toll. We say to one another: "What is bad for us may be good for others, so who are we to say what is good or bad?" That is the way many of us think, even when confronted with the enormity of the events of September 11.

We have become so sensitive to the "absolute" overtones of the word evil that to a great extent we avoid using it, and it has acquired a special aura. For that reason, when the Washington Post used the word in a banner headline on the day after the attack--"Under a Cloud of Evil"--it carried a high voltage. We treat the notion of evil as though it were our 16-inch gun--to be wheeled out and fired only on very special occasions: in reference to the Holocaust in World War II, or perhaps to some "hate crime" in America.

Of course, the terrorist attack and the consequent murder of thousands of innocent people was itself no ordinary event. On that ground alone, therefore, it should qualify for the dreaded label "evil." But my point is not that the attack deserves to be called evil because of its enormity, but because a very large number of routine events in our lives partake of evil to some degree. And it goes without saying that the terrorist attack did so to a large degree.

We are all immersed in evil, great and small, every day of the week. We do bad things routinely, when we lie or cheat or steal or succumb to any number of temptations. We are urged in the Lord's Prayer: "And lead us not into temptation, but deliver us from evil." Catholics in the pews are urged to go to Confession regularly not because evil is a thing of rare enormity, but because it is so everyday.

When Jesus enjoins us to pray that God might "deliver us from evil," it is not because we might otherwise be tempted to blow up buildings filled with thousands of innocent people, but because we might do something so inconspicuous as thinking ill of our neighbor. And if small animosities fall under the rubric of evil, as they do, then the large hatreds manifested by the terrorists certainly do likewise.