Aug 25 2014

Nassim Taleb, The Precautionary Principle, and GMOs

Nassim Taleb is a serious scholar of risk assessment, especially in the world of economics. So when he and two co-authors published a paper on the precautionary principle as it applies to genetically modified organisms it is worth taking seriously. That does not mean I have to agree with his conclusions, however.

What I found was that Taleb’s argument is mathematically rigorous, although I think too absolute, but also is biologically naive.

Here is his argument in a nutshell: The mathematical part if this – if we consider risk prevention, we must decide how much risk is acceptable. As risk increases, tolerance should decrease. As risk approaches infinity, tolerance should approach zero.

In order to use this principle, we must quantify risk, so he further argues that any risk of permanent harm or total harm should be considered infinite.

A way to formalize the ruin problem in terms of the destructive consequences of actions identifies harm as not about the amount of destruction, but rather a measure of the integrated level of destruction over the time it persists. When the impact of harm extends to all future times, i.e. forever, then the harm is infinite. When the harm is infinite, the product of any non-zero probability and the harm is also infinite, and it cannot be balanced against any potential gains, which are necessarily finite. This strategy for evaluation of harm as involving the duration of destruction can be used for localized harms for better assessment in risk management. Our focus here is on the case where destruction is complete for a system or an irreplaceable aspect of a system.

First, I’m not sure I agree with his conclusion that no benefit is worth any risk of total harm, what he calls “ruin.” Let’s say, for example, that physicists were conducting an experiment on a process that could produce controllable fusion. If successful, this would mean the ability to generate massive amounts of power cheaply and cleanly, a total game-change for our civilization, and one that would reduce many other risks, such as climate change.

However, there is a trillion to one chance that the experiment will create a black hole that will suck in the Earth and end humanity. Should we take the trillion to one chance? I’d role those dice.

Such extreme and contrived cases aside, I can accept his general precautionary principle. If the risk is the destruction of human civilization, extinction for humanity, destruction of Earth, or the ruin of Earth’s ecosystem, we should essentially have a zero tolerance for risk.

I don’t agree with his argument that any permanent harm should also be considered infinite. My question is – does this apply to any harm, no matter how small as long as it’s permanent? Taleb also adds as a criterion that the harms are generalized and not local. So, if the risk spreads to the entire system, we should consider it infinite and his precautionary principle should apply.

Taleb further defines some systems as fragile, meaning they have a non-linear response to harm. For example, if you fell from 1 foot 100 times you would probably be fine, but if you fell once from 100 feet you might be killed. As height from which one falls increases, harm dramatically increases until it is complete (death). However, below a certain threshold there is no harm, and so small falls do not accumulate damage.

The two systems to consider with regard to GMOs are human health and the ecosystem.  Taleb argues that both of these systems are fragile, that the risk of harm from GMOs is global and not local, and that such harm has the potential to be permanent, therefore we should apply his precautionary principle of zero risk.

However, Taleb also argues that the risk to the environment increases as more GMO are introduced. He is assuming cumulative risk, however, and this is where I think his argument is biologically naive. Nature is a robust system with many homeostatic mechanisms. Potential harm from unintended consequences are likely to be local and finite, not global and permanent.

As as example, one he uses himself, the introduction of invasive species (which are far more risky than GMOs) can have a devastating effect on an ecosystem, but the system does not collapse. A new equilibrium evolves. To be clear, I am not saying there is no harm from invasive species. We should make every effort to minimize their introduction, but the results are not total ruin.

Introduction of GMOs are like falling 1 foot – they will not add up to a 100 foot fall.

I also think his argument simply does not apply to human health. There is no such thing as zero risk with human health. Taleb argues about scientific uncertainty, unknown risks, and dismisses the “all risks are non-zero” argument. However, I don’t think his logic here is valid. Even eating a natural plant has non-zero risks. The only practical system that applies is risk vs benefit and risk tolerance levels. The FDA, and medical science are based on having a sufficient margin of safety – but never zero risk.

Another factor I felt was missing from Taleb’s calculations is considering the risks of alternatives. Growing enough food for 7 billion people has consequences, in terms of land use, fertilizer, pesticides, and displacing natural ecosystems. GMO as a technology can potentially add to our efficiency. Banning GMO means relying more heavily on other technologies that may have even more risks.

In the end I found Taleb’s arguments to still come down to hyping the risk of unforeseen consequences due to the inherent limits of scientific knowledge. I don’t agree, however, that GMOs have the potential for global ruin. This is still largely based on a naive belief that transgenes are inherently risky, when there is no scientific reason to believe that they are.

While he makes a much more elaborate argument about risk than most, in the end it still comes down to how risky you think specific GMO species are, and what margin of safety you think is acceptable from scientific evidence. He failed to make a compelling argument that his principle of zero risk should apply to GMO.

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