Unintended Consequences

In social science, unintended consequences (often unanticipated consequences or unforeseen consequences) are outcomes that are not the ones foreseen and intended by a purposeful action. The term was popularised in the twentieth century by American sociologist Robert K. Merton.

Unintended consequences can be grouped into three types:

• Perverse results: A perverse result is an outcome that is contrary to what was originally intended. This happens when an intervention in a system produces effects that are exactly the reverse of the effects which were intended to happen. These can be either negative outcomes which were not anticipated, or positive outcomes which were not desired.
• Unanticipated side-effects: Unanticipated side-effects are outcomes which were not specifically foreseen, but fall outside of the perverse results category because they are still reasonably aligned with the original goals of the intervention. They may be either positive or negative.
• Systemic effects: Systemic effects are broader impacts produced by an intervention, often indirect and long-term impacts which were not foreseen at all. These tend to be negative outcomes, particularly when they result in feedback loops which amplify the original problem.