unintended consequences

Boomerang effect (psychology) – Unintended effect of persuasion

Collateral damage – Unintended consequences done to third parties

Domino effect – Cumulative effect produced when one event sets off a chain of other events

Dutch disease – Theory in economics

Ethics in mathematics – Emerging field of applied ethics

Externality – In economics, an imposed cost or benefit

Knightian uncertainty – Lack of quantifiable knowledge in economics

Map–territory relation – Relationship between an object and a representation of that object

Moral hazard – Increases in the exposure to risk when insured, or when another bears the cost

Parable of the broken window – Parable by French economist Frédéric Bastiat

Rebound effect – Pharmacological term

Rebound effect (conservation) – Increase in consumption following energy or resource savings

Paradoxical reaction – Effect of drug opposite to expectation

Parkinson's law – Adage that work expands to fill its available time

Streisand effect – Increased awareness of something after suppression efforts

System accident – Unanticipated interaction of multiple failures in a complex system

Systemantics – Book by John Gall

Technology assessment – Determining the value of a new technology

The Rhetoric of Reaction – 1991 book by Albert O. Hirschman (appearing as the "perversity thesis")

Tragedy of the commons – Overuse of a shared resource

Virtuous circle and vicious circle – Self-reinforcing sequence of events