Americans are overreacting to events: to the "Great Depression" of 2009, to the increasing numbers of young people with Attention Deficit Disorder, to the histrionic fantasy that climate change will become global boiling. None of these issues is without substance, and none of them should be ignored; but in one way or another, we are overreacting by turning each of them into a crisis.

We seem to have fallen in love with crises, and the more crises we find the more animated we seem to be. We are immersed in a Crisis of Crises, replete with illogic, a surfeit of emotion, and strings of events vying for crisis status.

"Crisis," literally, means separation, and involves a break with the past by supplanting the existing order with a new one. Tectonic departures from precedent such as the transition from B.C. to A.D., from the ancien régime to the French Republic, from the Romanovs to the Bolsheviks, were set off by crises. Both the Russian and French revolutions included a change in their calendars. Illegal immigration, farm "crises," daily energy "crises," credit card "crises," E. coli contamination "crises," and education "crises" express substantive concerns, but they are not and never were crises in the strict sense of the term.

So what is overreaction? Simply put, overreaction is characterized by its reliance on emotion, its episodic time frame and, ultimately, its retreat from reality. Take the worldwide swine flu pandemic. No doubt, researchers have locked onto a serious health threat that will require a forceful response-immunization, rapid diagnosis, public health precautions, and ongoing research. An important moderating factor is the high probability that anyone who was infected with the virus between 1946 and 1953 is likely to be immune to the disease.

But the public has responded with less moderate emotions, donning surgical masks, avoiding crowds, and gulping down "immune-boosting" pills. No doubt, swine flu infection is a real phenomenon, and a scary one which, by dint of a single mutation, could cast a giant shadow across the American continent. But when we look at the facts we find both our feet on the ground. H1N1, as infectious disease specialists call it, is closely related to influenza virus A, which brings the flu each winter. The most recent attack, one that was carefully studied, took place in Mexico in late April, and the death rate was calculated at 0.6 percent.

Admittedly, H1N1 has hogged the airways because it is the same virus that caused the Spanish Influenza of 1918 and killed 50-100 million people worldwide. But the reaction to the news about H1N1 has been nearly hysterical, not by researchers who calmly poke their noses into high-risk settings but by ordinary people who imagine large-scale scenarios of death and dying. Given the changes in our ability to launch an antiviral "war" we should regard this disease as a serious problem-and one for which we have a coordinated repertoire of responses. A serious problem, Yes; a crisis, No.

A captivating example of overreaction involves the volatile responses to a 1998 article in Lancet, which described an alleged new disorder called autistic enterocolitis. The authors stated unequivocally that they had not established a connection between the measles, mumps, and rubella (MMR) vaccine and this new condition. But at a post-publication press conference, one of the authors surprised his coauthors and recommended that children should have the opportunity to receive the vaccines separately, with a year between doses. Though the article itself had not made a splash, this single remark ignited a furious reaction that caught the imagination of the media. The result was a decrease in the number of children whose parents approved of the vaccine, a decrease that produced a real threat of an outbreak of measles-and all because of the overreaction of the press and public to one stray remark from one coauthor that was disavowed by his colleagues.