But the real lesson of the oil spill may be how bad we are at dealing with unlikely but disastrous events. "We deal with them by ignoring them until they happen, and then overreacting," says John Harrald, a professor at George Washington University's Institute for Crisis, Disaster, and Risk Management. It's one thing to look back and figure out how the oil spill could have been prevented. It's another to grapple with the combination of poor foresight and 20/20 hindsight that makes preventing these meltdowns so difficult…. The problem begins with the way we assess risk. The less likely an event, the less a company—or a government, or an individual—feels the need to guard against it…. Another problem is that some precautions only make sense hindsight…. Then there's the difficulty of cost-benefit analysis when it comes to low-probability, high-consequence events. The full costs of an oil spill are difficult to estimate—even decades later."