From the BP oil spill to Hurricane Katrina, why are we so unprepared when disaster strikes? Richard A. Posner, a judge on the U.S. Court of Appeals and senior lecturer at the University of Chicago Law School, thinks it may have something to do with the human tendency to procrastinate. Posner says that without certainty about when the disaster will actually occur, people postpone preventive action because it’s costly and our priorities lie with the present. “Our tendency to procrastinate is aggravated by three additional circumstances: when fixing things after the fact seems like a feasible alternative to preventing disaster in the first place; when the people responsible have a short time horizon; and when the risk is uncertain in the sense that no objective probability can be attached to it.” We could rank potential disasters by probability and cost, and decide how to proceed. But the consequences and probabilities of disasters are usually unknown, and it’s also difficult to reward prevention for low-probability risk. So, as long as “there are so many risks of disaster that they can’t all be addressed without bankrupting the world many times over,” we will remain vulnerable to threats like the recent BP oil spill or the global financial crisis of 2008.