A quiet spring day on a rural campus — then suddenly shots, shouting, chaos, death. Our minds cannot absorb such fathomless violence. We need to impose order on it, find explanations. And so, within minutes of the mass murder at Virginia Tech University, a great conversation erupted as Americans — and the rest of the world — tried to make sense of the senseless.

It was a classic American crime: an angry loner, enraged by the failure of a love affair, turns his anger on the world around him. Think of John Muhammad, the Washington sniper of 2001; John Hinckley, the would-be assassin of Ronald Reagan; Charles Whitman, the clock-tower killer at the University of Texas, whose 1966 rampage was until this week the deadliest campus crime in American history.

Such stories are too random and terrifying for the mind to absorb. So instead, we attempt to squeeze these crimes into our pre-existing categories and use them to advance our ideological agendas and thereby apportion blame. In the hours since Monday’s attacks, three such categories have been presented to the American public.

The one probably most familiar to British audiences attributes killings such as those at Virginia Tech to the easy availability of firearms in America. There is some truth in this. The murderer, Cho Seung-Hui, appears to have legally purchased a Glock 9mm automatic pistol shortly before the attack. Had it been more difficult to buy such a weapon, perhaps his crime could have been prevented — or at least rendered less lethal.

There is also an element of plausibility to the second explanation — the feminist one. Even in countries where guns are difficult to obtain, male sexual jealousy does daily, deadly damage. The British Home Office contends that domestic violence kills more young women worldwide than war, cancer, and motor vehicle accidents.

Then there’s the third and final explanation — immigration. Seung-Hui was a Korean-born resident alien. Aliens increasingly drive the American crime problem: about one third of California’s prison population is first- or second-generation immigrant, as is 29% of the federal prison population. Salvadoran and other Central American gangs commit the worst violence in many American cities. The finger of blame is easily pointed.

So which shall we blame? Guns? The male psyche? Immigration? None of the above? Or some of all of the above?

Typically, it’s the first — America’s gun culture — that most readily captures the rest of the world’s imagination. After the Concordia University massacre in 1992, Canada adopted a strong new gun-control law. Yet Americans have been far more reluctant to respond to gun violence with legislation. Bill Clinton proposed only a few small refinements to American gun laws after the 1999 Columbine massacre.

America last tightened its gun laws in 1993 — and many Democrats blame that decision for their defeat in the 1994 congressional elections. Some blamed Mr. Clinton’s 1999 initiatives for helping to tip Arkansas and Tennessee to President Bush in 2000, and the party has eschewed the gun issue ever since.

This was perhaps because lower-income males were identified as a must-win demographic — and guns, therefore, an issue that cost more votes than it gained. In 2004, John Kerry posed for the cameras in duck-hunting gear. In 2006, Democrats recruited as a star senatorial candidate former Secretary of the Navy, James Webb, a lifelong gun enthusiast.

So will the Democrats revert to gun control as an issue for 2008?

Neither Hillary Clinton nor Barack Obama can afford to do anything that might alienate the downmarket males who returned to the Democrats in 2006. And hopes of holding the Senate will turn on the party’s success in retaking southern and western seats lost in 2002. The Democrats hope to gain Senate seats in Colorado, New Hampshire, and Oregon in 2008 — and gun owners form an important share of the swing vote in all three.

On the other hand, Democratic support for new gun controls could risk seats in Arkansas and South Dakota. Not much debate to be found there, then.

Nor will we find much appetite to launch national discussions about male sexual possessiveness or immigrant crime. Why blame all immigrants for the crimes of one, people on the left will sensibly ask. Good point, the right will respond — so why blame all men for the crimes of one?

But this welcome skepticism leads inevitably to the most skeptical of all questions: why are we blaming anything or anyone for this crime other than the criminal himself?

Crime can be reduced. Since 1990, the number of homicides in America has been cut from almost 25,000 a year to about 15,000. Schools have launched programs to predict potentially violent students. Some require transparent backpacks, and others have instituted sophisticated psychological profiling. All will pounce on any student joke about copycatting Columbine. Meanwhile, many local police departments have attempted to modernize their tactics.

America will try to learn lessons from this latest tragedy too. But there is no escaping the hardest lesson: that death lies waiting around the corner for us all.

No public policy can rescue us from that grim human fact — or the equally fearful obligation to walk with courage under the burden of the reality of evil and the randomness of fate the world over.

Mr. Frum was a speechwriter for President Bush between 2001 and 2002.