'The thing I fear most is fear." This was Montaigne, in an early essay, many centuries before Roosevelt. "It exceeds all other disorders in intensity." He was endorsing an ancient fear of fear, according to which it is a disgrace, and the most formidable enemy of reason, and therefore an impediment to self-control, and to thoughtful action. The mastery of fear, in this tradition, is one of the signs of the attainment of wisdom. I am being a little bookish, but I heard echoes of this delegitimation of fear in Barack Obama's speech on national security at the National Archives. He always referred to fear derisively--"all too often our government made decisions based on fear rather than foresight"; "we will be ill-served by ... fear-mongering" and by words that "are calculated to scare people rather than educate them," and so on. He warned against "fodder for 30-second commercials" and "direct mail pieces ... designed to frighten the population." It did not hurt Obama's argument that even as he was rising above alarmism Cheney was making a commercial for it across town. In the disputation between Vice-President Dracula and President van Helsing, the choice seemed easy. A little too easy, actually. So I would like to say a few words on behalf of fear, before our national security policy settles into a misplaced stoicism.

There are two ways in which one can alter one's experience of the world. One can change the world, or one can change one's attitude toward the world. But the world will not be altered by a change in our attitude toward it; or more precisely, only that part of it will be altered that is determined by our attitude toward it. This leaves a great deal of analytical work to be done. We can control our beliefs and our actions. But which of our circumstances are caused by our beliefs and our actions, and which by the beliefs and the actions of other people, who are just as autonomous, and just as animated by their own reasons, as we are? We must not mistake a mastery of ourselves for a mastery of the world. Self-control is control only of the self; and for this reason it is often a mild withdrawal, an elegant form of detachment from whatever escapes our power but causes us pain. The problem is that the protection of oneself is not yet the protection of others. Fear is often a social unease. If societies cannot run on panic, neither can they run on calm. For even if we extirpate from our minds all of fear's infirmities, we will still discover that some of what frightens us has a cognitive basis, that certain dangers are incontrovertibly real. Is fear sometimes stupid? Then fearlessness is sometimes stupid, too. The question is when. But calm may be the most cunning kind of demagoguery, because it looks so much like the opposite.

These judgments are infamously difficult to make. Where we need the most certainty, we have the least certainty. Instead we operate in the emotionally volatile universe of probability. "Probability arises from an opposition of contrary chances or causes," Hume observed, "by which the mind is not allow'd to fix on either side, but is incessantly tost from one to another, and at one moment is determin'd to consider an object as existent, and at another moment as the contrary." He was writing about fear and hope, and it is a fine depiction of the way we think now. In matters of national safety, I do not see how we can proceed responsibly without a respect for fear. The imagination of disaster is an intellectual condition for homeland security. Fear, too, may be a variety of foresight. If a candid account of our vulnerabilities is a way of scaring the American people, then to scare them is also to educate them--or, in the current parlance of Obama love, to treat them like adults. (In other realms of risk--health, product safety, climate change--many liberals tolerate alarmism as just a lurid form of prudence.) Like all prejudice, which is never an empirical conclusion and so cannot be explained by reference to its object, anti-Americanism cannot be explained entirely by reference to America, even to Bush's America: we have turned our new page in our relations with the world, but in Pakistan they are burning effigies of the president whose middle name is Hussein. Have we exchanged Bush's surfeit of confidence for Obama's surfeit of confidence? In this hour of progress, a sense of plasticity should be complicated by a sense of facticity. In an endlessly stimulating book called Laws of Fear, Cass Sunstein unhysterically proposes what he calls "the Anti- Catastrophe Principle." He means this as a supplement to all the sophistication that is required of governmental action about risk; as a concept with which we may arm ourselves against worst-case scenarios for which we cannot be adequately consoled by considerations of improbability. Sunstein prefers "technocrats" to "populists," and champions the correction of feeling by study-- and yet he insists that there may be dire eventualities that justify aggressive measures for the purpose of prevention, and that this principle "has a definite place in both life and law." Ponder the applications to our security of his deceptively simple prescription: "If public fear cannot be alleviated without risk reduction, then government reasonably engages in risk reduction."

It is cruel to shame people for their fears, because their fears are measures of their attachments. A life with nothing to lose is a serene and hollow life. (Worry, as my mother once said to me, shows an interest.) And political leadership is in part the art of preparing people for struggle. The scanting of fear is not a foundation for a summons to courage. The peculiar thing about Obama's discourses on national security is that they do not speak of courage. In this way he is unlike Roosevelt, whose "fear itself" speech was premised upon the recognition of fear--of warranted fear--but warned of its inhibiting effects, and then ascended to an appreciation of "warm courage." Obama does not call on us to be brave; he calls on us to be good, and to be cool. When he declares that "our values have been our best national security asset," I do not know quite what he means. He promises a pristinity that the fight may not allow. If our means should not be mistaken for our ends, neither should our ends be mistaken for our means. Our values are not what protect us, they are what we protect--not by traducing them, obviously, but also not by losing ourselves in the adoration of their beauty. Our values are why we were attacked. And so there is moral truth in a cold sweat, and civic dignity in a sleepless night.

Leon Wieseltier is the literary editor at The New Republic.

By Leon Wieseltier