The Collingridge Dilemma
In 1980 David Collingridge, an obscure academic at the University of Aston in the UK, published an important book called The Social Control of Technology, which set the tone of many subsequent debates about technology assessment.
In it, he articulated what has become known as "The Collingridge dilemma"—the idea that there is always a trade-off between knowing the impact of a given technology and the ease of influencing its social, political, and innovation trajectories.
Collingridge's basic insight was that we can successfully regulate a given technology when it's still young and unpopular and thus probably still hiding its unanticipated and undesireable consequences—or we can wait and see what those consequences are but then risk losing control over its regulation.
Or as Collingridge himself so eloquently put it: "When change is easy, the need for it cannot be foreseen; when the need for change is apparent, change has become expensive, difficult and time consuming."
It's called a "dilemma" for good reasons—Collingridge didn't like this state of affairs and wanted to solve it (mostly by urging us to exert more control over the social life of a given technology).
Still, even unsolved, the Collingridge dilemma is one of the most elegant ways to explain many of the complex ethical and technological quandaries—think drones or automated facial recognition—that plague our globalized world today.