The Lack of Clarity in the Precautionary Principle

The precautionary principle states, roughly, that it is better to take precautionary measures now than to deal with serious harms to the environment or human health later on. This paper builds on the work of Neil A. Manson in order to show that the precautionary principle, in all of its forms, is fraught with vagueness and ambiguity. We examine the version of the precautionary principle that was formulated at the Wingspread Conference sponsored by the Science and Environmental Health Network in 1998. That version fails to indicate who must bear the cost of precaution; what constitutes a threat of harm; how much precaution is too much; and what should be done when environmental concerns and concern for human health pull in different directions. Whether this vagueness is a strength or weakness of the principle depends on what purpose(s) the precautionary principle is supposed to serve.