some definitions

It is important here to distinguish between unanticipated and undesired consequences. The former are consequences which are not foreseen and dealt with in advance of their appearance. Undesired consequences are those which we are harmful, but which we are willing to accept, or accept the risk of occurring. Consequences may be:

Anticipated

• intended and desired
• not desired but common or probable
• not desired and improbable

Unanticipated

• desirable
• undesirable

As an example, consider the development of a nuclear power plant at an ocean site. The anticipated and intended goal or consequence is the production of electric power. The undesired but common and expected consequence is the heating of the ocean water near the plant. An undesired and improbable consequence would be a major explosion, and we would associate the term 'risk' with this outcome, but not with the heating of the water.

An unanticipated and desirable consequence might be the discovery of new operating procedures which would make nuclear power safer. An unforeseen and undesirable consequence might be the evolution of a new species of predator fish, in the warmed ocean water, which destroy existing desired species.

This paper concentrates on unanticipated consequences of our technologies. Anticipated negative consequences have been dealt with extensively in the literature on risk. See, for example, Margolis (1996), and Bernstein (1996). The latter emphasizes the role of mathematics in risk assessment.

Two brief points should be made before we proceed. The first is that change is always with us. Even without the intervention of human beings, nature changes constantly. Continents move, weather changes, species evolve, new worlds are born and old ones die. The second point is that all change seems to involve unanticipated consequences. Hence, the unanticipated is a part of life. There is no absolute security. Unanticipated consequences can be mitigated, largely through the gaining of additional information or knowledge, but not eliminated. That's the nature of our life, natural and human.