Change is our only certainty. How we handle it is important. Some risks can be reduced or insured against, such as illness, auto wrecks, and fires. But many risks offer opportunities. Progress implies change and change implies risk.

But when considering our environment, many would avoid all risks. Instead they defer to the "precautionary principle." One popular version, the Wingspan Declaration, states: "When an activity raises threats of harm to human health or the environment, precautionary measures should be taken, even if some cause-and-effect relationships are not fully established scientifically."

This may initially sound reasonable, but it collapses when examined.

Very few actions are risk free. Most activities yield both benefits and costs. For example, downhill skiing is fun and improves one's health, but it also dramatically increases the risk of broken bones and blown-out knees. Further, in choosing and following one course of action, we forgo others. If we skied Bridger all day Monday, we missed St. Patrick's Day in Butte. Thus, any action implies the cost of foregone opportunities.

The regulation of greenhouse gases provides an excellent example. The risk from not reducing emissions of such gases is that we may increase global warming, which will certainly have some adverse effects. But the risk to imposing restrictions on the output of these gases is that the cost of compliance will surely slow economic progress. This would be particularly damaging to the poor of the Third World. Even if restrictions on GHGs are imposed only on wealthy countries, the resulting decrease in economic growth will harm poor countries, which often rely on developed nations to buy their exports.

The argument is similar for genetically enhanced crops. Americans have been eating foods with GE ingredients since 1995 without adverse health effects. The health risks are no different from those of traditionally bred foods. As the National Academy of Sciences recently stated: "Foods from GE plants can potentially contain allergens or toxins.... These risks are not unique to GE foods. People have consumed foods containing allergens and toxins...throughout history."

There are environmental risks, e.g. from the possible creation of "superweeds." But the costs of preventing the use of GE crops are potentially huge. GE crops could increase the quantity and nutritional quality of food faster than conventional crops, particularly in developing nations. Given that almost 30 percent of humanity -- nearly 2 billion people -- suffer some form of malnutrition, the potential benefits of GE foods are evident. Preventing or even delaying their use causes unnecessary suffering and death and fosters dependence on foreign aid.

Ironically, the precautionary principle is inherently dangerous. I agree that the emission of GHGs and the use of GE crops raise "threats of harm to human health or the environment," even if not scientifically proven. Does this imply we should forbid their production and use? No, because reducing GHGs and avoiding GE foods have their own dangers. As liberal University of Chicago law professor Cass Sunstein argues, the precautionary principle "stands as an obstacle to regulation and nonregulation, and to everything in between."

As a result, the precautionary principle is often selectively applied, usually by environmentalists and other special interests. They look only at the risks of adopting new technologies. But they ignore the very real harm from not using new technologies.

The paralysis induced by such selective caution inhibits technological and economic progress. Many affluent Greens applaud this outcome. But the progress they condemn improves living conditions, especially for the poor. It also leads to cleaner, less resource-intensive technologies. It makes societies more resilient. They can better survive adverse events such as droughts, floods, disease, and global warming.

Had our ancestors not taken risks, we would still be hunter-gatherers living in caves. Following the precautionary principle would produce a race of cowering Hamlets, unable to choose a course of action, or a Kafkaesque world of bureaucrats endlessly debating the relative risks of acting -- and of debating.

Yes, we need to be careful and consider the impacts of our actions. We also need to weigh the costs of inaction -- especially to the poorest and weakest among us.