I have been pondering on writing about the precautionary principle for a while. I hesitated because of the vastness and intricacy of the matter, the apparently endless ramifications, and the somewhat controversial legal sides (see yourself!). I finally decided to go ahead, while keeping these notes close to the simple and powerful core idea.

The roots of the precautionary principle are often traced back to the preamble of the 1987 UN Montreal Protocol on the ozone layer and, particularly, to the Rio Declaration on Environment and Development, made on the 1992 Summit in Rio de Janeiro. Here, the 15th point reads:

In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.

The definition used by Schenllnhuber and Wenzel, in “Earth system analysis: integrating science for sustainability” (p. 209):

securing of error-tolerant operating by judiciously staying away from the currently presumed civilizatory and ecological load limits

is also illuminating because it emphasizes the links to a system dynamics approach, as well as the concept that the inherent limits in our knowledge give rise to uncertainties in forecasts and analysis. This applies specifically, for example, to the perceived safety of pollutants, insecticides, etc., and calls for extreme caution in their use.

There is, however, nothing truly revolutionary in these words, as the basic idea is as old as humanity itself and can be found, in subtle ways, in the the wisdom and common sense of many cultures (or grandmothers, for that matter). The point was brilliantly made by Nicholas Nassim Taleb in his book “Antifragile”, and goes basically like this: Do you ingest a bunch of randomly chosen pills on the premise that there is no evidence that they will do any harm to you? Well, no. The same applies to the environment!

The idea is closely connected with the concept of burden of proof. This translates in that those claiming that there is no harm in using a certain product or method are those who have to provide the evidence that these are safe, and not the opposite. With respect to the global environment, the lesson is that we cannot happily assume that we can just do anything on a massive scale without harming the planet, particularly if these assumptions are based on a limited number of isolated and possibly lousy experiments (or none at all). Compare this with the vast experimental record of natural evolution. In her millions of years of trial and error, Nature has come up with far better solutions, compatible with the rest of the environment, than anything humans can do. This point was also raised by Taleb, with a cute probabilistic interpretation (see here).

In recent decades we have witnessed a particularly successful application of the precautionary principle, namely the ban on chlorofluorocarbons (CFC) and the ensuing recovery of the ozone layer. We now have at hand another excellent example with the European Commission’s recent ban on neonicotinoids, that has conceivably put a stop for the colony collapse disorder in the Po river valley, Italy, without observable negative impact on the crop yield. The precautionary principle is also very relevant to the question of greenhouse gases and climate change, where we have an opportunity to act now, by drastically reducing emissions of greenhouse gases, and hopefully call it another case of successful application in the future.

The precautionary principle has been criticized for being vague and loose and, if taken to the extreme, an excuse for inaction. Some of these criticisms are valid, but are directed to particular applications and interpretations, rather than the principle in itself and does not invalidate it. Note that one of the most powerful aspects of the precautionary principle is how it is inextricably linked to ethics, guiding us to think on how our actions and decisions impact on Nature and our fellow humans, both now and in the future. Experience has shown that, when used as a guidance, in an open-minded and reasonable way, the precautionary principle makes a good starting point on any environmental discussion, and a solid ethical and practical ground for the legislation and practice of sustainable development. Let’s not forget it.

NOTE: originally published in my old blog “Tales of a Finite Planet”, on 2014-06-24

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