Johanna Thoma (LSE): “Time for Caution”

Precautionary principles are frequently appealed to both in public policy and in discussions of good individual decision-making. They prescribe omission or reduction of an activity, or taking precautionary measures whenever potential harmful effects of the activity surpass some threshold of likelihood and severity. One crucial appeal of precautionary principles has been that they seem to help guard against procrastinating on confronting and mitigating certain kinds of risk, namely those that are especially hard to quantify. Here I raise a challenge for precautionary principles serving as effective action-guiding tools to guard against (policy) inaction, procrastination, or recklessness. Given the fact that risks that are sufficiently harmful and sufficiently likely to fulfil the antecedent of a precautionary principle typically accumulate over time, precautionary principles are only effective if they constrain an agent’s decision-making over time. On the basis of this observation, I argue for two claims. First, to yield the normative verdicts proponents of precautionary principles would like to make, precautionary principles must be understood to be diachronic principles, which requires some added structure to how they are commonly formulated. And secondly, such diachronic precautionary principles invite policy procrastination and inaction in their own right, due to both the vagueness of thresholds of harm and likelihood, and because agents will often fail to abide by the principles if they ignore bygone risks.

Johanna Thoma is an Associate Professor in the Department of Philosophy, Logic and Scientific Method.