Gun control advocates moved swiftly in the hours following the horrific shootings in Aurora, Colorado. New York City Mayor Michael Bloomberg asked Mitt Romney and President Obama, "What are you going to do about [gun violence]?" and was joined by several others in suggesting that the United States would be better off with more restrictive gun laws. Mitt Romney and President Obama would be wise to answer, "There is little I could do as president to prevent another Aurora, and it would be foolish for me to try."
Any public policy proposal should, at the very least, consider both the expected benefits and possible costs associated with implementation. An optimal policy is one that addresses the problem in question, but does so with the lowest costs and highest benefits. The optimal number of multiple-victim public shootings is not zero, because the costs of trying doing to do so would outweigh the benefits
Automobile accidents, for example, kill far more people than multiple victim public shootings. In fact, there would have to be seven Aurora shootings every day of the year, plus 185 on Christmas, just to reach parity. We could adopt a national speed limit of five miles per hour to eliminate all risk of accidents. No one would die in car accidents, but police would be unable to respond to crimes, ambulances would be unable to transport people to hospitals in a timely manner, commerce would collapse, and travel would be nearly impossible. The high costs of eliminating all auto accidents outweigh the benefits, and this acknowledges that the optimal number of accidental automobile fatalities is likely several tens of thousands each year. Traffic fatalities are at all all-time low, but that's because of innovation, not commands from regulators.
Consider the Transportation Security Administration. While there hasn't been another hijacking since the TSA’s creation, intrusive security measures have caused millions of travelers to drive instead of fly for short trips. Driving is riskier than flying by orders of magnitude, and the resulting difference in flying rates may have caused several hundred deaths each year. Unless the enhanced pat-downs and body scans are preventing several large airline crashes each year, then the policy is causing more deaths, not fewer.
Like the examples above, the policy tools for preventing multiple victim public shootings are limited and have large attendant costs.
Some state and local governments have enacted gun-free zones without noting the irony that nearly every multiple victim public shooting takes place in a gun-free zone.
Police were on the scene in Aurora within 90 seconds of the first 9/11 call, but by then the damage was done. At Columbine High School the two shooters had killed thirteen people, then themselves, before SWAT entered the campus. Police are sometimes able to confront shooters and shorten the duration of a rampage--so are armed citizens--but they primarily provide emergency services after the shooting is over, and by then most of the victims are already dead. It would be impossible to give police greater powers without significant loss of freedom, and we have no reason to expect this to eliminate mass shootings.
A total ban on guns is another policy that won't help. Not only are criminals unlikely to adhere to gun laws, but guns are used defensively by hundreds of thousands of law-abiding Americans each year. Nor are guns required for killing large numbers of innocents. Timothy McVeigh was able to kill 168 people armed primarily with fertilizer and car fuel. His attack was executed with a budget of less than $5,000. But you don't have to take my word for it: countries with gun bans still suffer from mass shootings.
What prevents more multiple victim public shootings from occurring is not a police deterrent, gun bans, gun free zones, or even laws against murder. Rather, they are relatively rare simply because most people are unwilling to do such a thing, and perhaps this is why mass shootings are so frightening. As Adam Bates noted in the Daily Caller, many mass murderers are insane, and the lesson is that "there are some problems for which there is simply no tangible solution."
This doesn't mean we are doomed, by any means. We live in one of the least violent periods in the history of mankind. The trend of lower violence will probably continue, but it will result from the shared moral values of the American populace. We should think twice before enacting policies aimed at eliminating multiple victim public shootings, because the costs of doing so almost certainly outweigh the benefits.