Earlier this month a U.S. air marshal killed a man aboard an American Airlines plane in Miami. The victim was carrying no explosives. Suffering from bipolar disorder and off his medication, he had issued threats. Taking no chances, the air marshal shot him.

Days afterward, Boston Globe columnist James Carroll wondered if we have not become a hair-trigger nation so obsessed with risks that we have turned our guardians into our potential killers. Carroll also asked if the Miami incident “isn’t the domestic equivalent of this nation’s hair-trigger foreign policy?”

Americans are fond of the phrase “better safe than sorry.” Some suggest it was far better to shoot this threatening character than to allow him to blow up a planeload of innocent passengers. One hopes that more details will emerge, but in a longer-term perspective, I think we are dangerously selective in our assessment of risks.

We also too easily allow fear of mysterious dangers to morph into fear of all forms of difference. In the process, freedoms are diminished and the quality of life undermined. Paradoxically, the world itself becomes more dangerous.

The Miami airport story resonates with me. I find airports to be creepy places. Since 9-11, I have taken eight round-trip flights, four to Arizona for a vacation and four to eastern cities for political science conventions. On six of those eight flights, I have been the only passenger in a relatively long line to be singled out for intensive search of my body and clothes. On my last trip, to Washington, D.C., I was intensively searched both in Bangor and at Reagan National.

I do not ask what triggers these searches. I am sure “security reasons” preclude agents’ revealing this information. I also fear agents might take such a question as resistance or provocation. I am not so enamored of my work as to suspect any federal officials have read it and classed me as a threat. Nonetheless, in my worst moments I have visions of being carted off somewhere and subject to interrogation without being able to contact friends or attorneys.

My late senior colleague at The Progressive, Erwin Knoll, had a huge FBI file obtained through Freedom of Information litigation. His file included extensive clippings from his columns. Most interestingly, the FBI had redacted large sections of these articles and editorials even though any of these columns could be located in newspaper archives. My experience looking over his files has left lingering concerns even as to the intelligence or training of the security bureaucrats.

Just a few days before the federal air marshal gunned down his man in Miami, the Bush administration was trying to scuttle Montreal initiatives on climate change. The administration no longer denies global warming. Instead, it maintains that predictions as to the extent and speed of the process are indeterminate. Thus, any actions taken to mitigate global warming must not damage our economy. It seems that better safe than sorry extends only so far.

A number of prominent European leaders in both the scientific and environmental community consider climate change a threat at least on par with so-called Islamic terrorism. A study by the Pentagon during President Bush’s first term raised similar alarms. Most interestingly, the Pentagon predicted vast population migrations in response to natural disasters. Is New Orleans a precursor?

At the start of the 21st century, Americans experience the “outsourcing” of many of our best jobs, the collapse of pension systems, a mass culture continually reshaped by media conglomerates, and diseases that travel at the speed of a bird or a plane. In response, many citizens fall back on the tried and true, a faith in the nation, literal interpretations of the Bible and the Constitution, corporate markets and economic growth. These ideals are increasingly coupled with growing hatred of those who cannot endorse or live these norms.

If half the predictions regarding global warming are true and our physical infrastructure deteriorates further, resistance to and hatred of those who are different may intensify. Such was the experience of medieval society during the great plagues.

For my money, better safe than sorry translates into a refusal to assume that the natural and cultural worlds were designed to fit even our most cherished ideals. It means accepting and even learning to take delight in a world where nature, including human nature, is never fully orderly or predictable. Our best bets lie in remaining attentive to the downsides of any technology.

In the social realm, we must periodically negotiate and revise, both among ourselves and with other nations, procedures and policy agendas that will allow increasingly blended, polyglot and evolving cultures to live and thrive together.

We may need guards on our planes, but if we can’t curb our quest to make the world fit our image, we may end up shooting at growing numbers of ghosts while our coastal cities are flooded.

John Buell is a political economist who lives in Southwest Harbor. Readers wishing to contact him may e-mail messages to jbuell@acadia.net.