That's why I have some trouble swallowing poor arguments that are started with the phrase 'Applying the precautionary principle...". The Precautionary Principle as it is popularly applied is a plea for perfect safety which is an unachievable goal. The need for evidence of harm or potential harm is dismissed by a person using the aforementioned phrase in a discussion. The demonstrable logical fallacies of the Precautionary Principle also mean arguments shored up with its statement are essentially without merit.
I've had some difficulty dredging up a formal statement of the Precautionary Principle, the best I could find is as follows:
If an action might cause severe or irreversible harm then the burden of proof falls on those that advocate taking the action.This is a slight paraphrase of the statement of the principle found on Wikipedia. Wikipedia is not the most reliable resource for factual information, but I feel it is fairly representative of how most people on the internet perceive a fact or principle. In this post I'm commenting on the popular statement and popular application of the precautionary principle rather than the formal statement of it (which I had trouble finding in a cursory internet search).
In and of itself this statement seems somewhat innocuous until you go back and look closely at the underlined word. A baseless accusation of possible harm due to an action under consideration can be made and the burden of proof lies at the feet of the proponents of the action rather than at the feet of the accuser. This strikes me as somewhat nonsensical as it is the legal equivalent of the presumption of guilt. A good analogy would be to ban the consumption of solid food because someone may choke to death. Sorry all your food must be pureed lest get something lodged in your throat, it might happen after all! As you can see from my analogy there is no evaluation of probability associated with the Precautionary Principle. The Precautionary Principle doesn't care if the odds of choking are one in a billion or approaching unity you now have to eat pureed food for the rest of your life.
Looking at the Precautionary Principle from a formal logic perspective we can demonstrate that it is a logical fallacy. Specifically the Precautionary Principle can be considered to be a straightforward Burden of Proof Fallacy . Burden of Proof fallacy occurs when the wrong side is required provide evidence. In the case of the Precautionary Principle as popularly stated the burden of proof is being placed solely on the advocate rather than also requiring the opponent to provide evidence of potential harm.
In this article which purports to lament the misuse of the Precautionary Principle the authors spell out the Burden of Proof Fallacy fairly clearly as follows:
The objectors must bring forward evidence that stands up to scrutiny, but they do not have to prove that there are serious dangers. It is for the innovators to establish beyond reasonable doubt that what they are proposing is safe. The burden of proof is on them.
The quote above is conflating two conditions to mislead the reader into accepting the Precautionary Principle as a reasonable and logical moral. In fact there is a further formal logical fallacy in the above quote known as Special Pleading. The author pleads a special case for the objector's burden of proof rather than applying the same standard of proof to the objector and the innovator. There is no relevant difference between the objector and the innovator, other than the appeal to the fear of harm due to the innovation which is yet another fallacy.
Well let's also consider an accusation by one of Silent Spring's detractors, that the ban of DDT is responsible of millions of malarial deaths worldwide every year. DDT was one of the world most effective anti-malarial strategies prior to the banning of DDT in the 1970's1 .
Remember there is no requirement for proof if we apply the Precautionary Principle, the burden of proof in each case is on the people proposing action hence the lack of citations supporting either case.
Where does the Precautionary Principle lead us? In this case the Precautionary Principle argues for both action and inaction. On one hand we have bird's reproductive success and on the other we have millions of human deaths. The Precautionary Principle because of how it's stated doesn't allow discrimination between the conflicting requirements, we must both stop using DDT to save eggshells and we must continue using DDT to prevent deaths from malaria. There's no middle ground and the Precautionary Principle provides no guidance on how to discriminate between risks.
Risk management is the identification, assessment, and prioritization of risks followed by coordinated and economical application of resources to minimize, monitor, and control the probability and/or impact of unfortunate events2.I consider the Precautionary Principle to be absolutely devoid of merit but without offering an alternative I'm just indulging myself in plaintively crying into my beer. So consider the Risk Management as an alternative. Applying Risk Management to the DDT example, we assign values to the two identified risks and to the costs of mitigating the risks. We can then decide between the lesser of two evils rather than remain stuck in the Mexican Standoff of the Precautionary Principle in the event of conflicting risks. Part of the process of Risk Management must be the thorough and rigorous proof of both risk and beneficial outcome in order to correctly identify and assess the costs of risk and the costs of risk mitigation.
The last point I want to make is about the misuse of the Precautionary Principle in discourse between individuals. In my experience entire well structured reasonable rational arguments are dismissed with a wave of the Precautionary Principle wand. If you don't want to be rational about an issue then be open about the fact that emotion dictates how you form decisions and is an intrinsic part of the opinions you hold. Don't get into a reasoned discourse and expect to use the Precautionary Principle to void arguments wholesale, it the equivalent of bringing a bouquet of flowers to a knife fight.
1 It is believed that [malaria] afflicts between 300 and 500 million every year, causing up to 2.7 million deaths, mainly among children under five years. Africa News, January 27, 1999] http://www.junkscience.com/ddtfaq.html
2 Douglas Hubbard "The Failure of Risk Management: Why It's Broken and How to Fix It" pg. 46, John Wiley & Sons, 2009