Den s.k. försiktighetsprincipen kan formuleras på följande vis:

[I]f an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is not harmful falls on those taking the action.

Denna princip används ofta för att argumentera för politiska beslut som, även om de inte bygger på solid vetenskaplig grund och även om de är dokumenterat kostsamma, anses kunna reducera allvarliga risker. Det finns mycket skrivet om denna princip. Jonathan Adler formulerar t.ex. en kritik i ”The Problems with Precauction: A Principle without Principle”, publicerad i The American; Christian Munthe formulerar en vidareutveckling och ett försvar i boken The Price of Precaution and the Ethics of Risk.

Det jag vill lyfta fram här är dock en invändning av Ilya Somin:

Incorporating the precautionary principle into public policy is itself “an activity [that] raises threats of harm to human health or the environment.” Adherence to the principle might prevent or retard the adoption of new technologies and policies that could save many lives. For example, application of the precautionary principle to prevent the use of genetically modified foods may cause mass starvation in Africa. The precautionary principle could also prevent or slow down policies that increase economic growth, which might also cost many lives. … Since it is the “proponent of an activity” that “should bear the burden of proof” under the precautionary principle, the principle counsels against its own adoption unless and until its advocates can prove that it won’t cause “harm to human health or the environment” in any of the above ways. Moreover, they must effectively address even those possible “threats” that “are not fully established scientifically.” Advocates of the principle haven’t even come close to meeting that burden of proof.

Detta ter sig i mina ögon som en stark invändning, åtminstone mot konventionella formuleringar av principen.