Iatrogenics is when a treatment causes more harm than benefit. As iatros means healer in Greek, the word means “caused by the healer” or “brought by the healer.”  Healer, in this sense, need not mean doctor, but anyone intervening to solve a problem. For example, it could be a thought leader, a CEO, a government, or a coalition of the willing. Nassim Taleb calls these people interventionistas. Often these people come armed with solutions to solve the first-order consequences of a decision but create worse second and subsequent order consequences. Luckily, for them at least, they’re never around to see the train wreck they created.

Today we use the phrase iatrogenics to refer to any effect resulting from intervention in excess of gain. Some examples are easier recognized than others. For example, when the negative effects are immediate and visible and appear to be a direct cause-effect, we can reasonably conclude that the intervention caused a negative effect. However, if the negative effects are delayed or could be explained by multiple causes, we are less likely to conclude the intervention caused them.

A great example of iatrogenics in action is the death of George Washington. In 1799, as he lay dying from a bacterial infection, his well-intentioned doctors aided or hastened his death using the standard treatment at the time, which was bloodletting (at least five pints, according to Ron Chernow).

More controversial examples exist as well, such as military interventions in the Middle East. In these cases, linkages are clouded by narratives, moral arguments, and clear cause and impact. (A great book to read on this is Perilous Interventions.) And when the linkages between cause and effect are murky, the very people who caused the harm are often the people rewarded for improving the situation.

The key lesson here is that if we are to intervene, we need a solid idea of not only the benefits of our interventions but also the harm we may cause—the second and subsequent order consequences.