FINDING a way to live on our planet without destroying or using up its limited resources is essential to humanity鈥檚 survival. It is one of our toughest challenges, as it requires a combination of science with economics, law and policy. This weekend, international leaders and policy-makers will meet at , to take stock of progress in sustainable development and set new goals for the next 10 years.
Before moving forward, however, we need policies that stand on firm foundations. One of the key pillars of sustainable policy is the precautionary principle, a concept adopted by . In essence, it states that if you want to do something that might harm the environment, and the science relating to the risk is uncertain, then you must take care.
A historic conference on the at Wingspread, Wisconsin, in 1998, introduced the idea of a 鈥渃ausal link鈥� between activities and harm. The idea was adopted by the European Union in 2000 and has since become pivotal in policy discussions relating to the principle. In May this year, the that differentiate between situations where the science relating to a potential threat is uncertain and where it is relatively certain. It defines 鈥渞elatively certain鈥� as meaning a causal link can be scientifically established.
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This might all sound reasonable, but there is a philosophical problem here. In the 1700s, the philosopher showed that presenting science this way is fundamentally flawed. A simple example: how do you know that the sun will rise tomorrow? Well, because you have seen it rise on hundreds of mornings; because it has always done so; because day always follows night. But Hume showed that such a conclusion is derived from habit, not logic. No matter how many events we observe there can always be an exception 鈥� and we can never say that because night ends, day must follow.
No one loses sleep worrying whether the sun will rise tomorrow; we strongly expect it will, and we plan our activities accordingly. But such habits are dangerous in science, and it is precisely through questioning them that our knowledge progresses. Newton鈥檚 theory of gravity seemed to have perfect predictive power until Einstein showed it to be flawed. Since then, Einstein鈥檚 theory has been found wanting, and so it goes on. As said: 鈥淭here is no truth, only progress.鈥�
The scientific method was designed to take this into account. Instead of trying to establish facts that are definitely true, scientists look for results that disprove their hypotheses. Seen in this light, science can never deliver what the new interpretation of the precautionary principle promises.
This may seem an obscure point, but it has profound practical implications. How can we logically apply the principle to determine whether there is a causal link between human activities and damage to natural resources when by definition the science is uncertain? When policy-makers ask for such a link, scientists cannot give an honest answer. Management under these terms is bound to lead to muddied, incoherent policies, with some activities not treated with the caution they deserve, and vice versa.
鈥淚f policy-makers ask for proof of causation, scientists cannot give an honest answer鈥�
Further, by overstating what science can achieve and ignoring its underlying principles, scientists become complacent. We dull its cutting edge because we allow our current ideas more permanence than they merit.
The precautionary principle has value: we are now more cautious about undertaking activities that may harm ourselves or our environment. But we need philosophy too. Science is not flawless or limitless, not least because we humans, with our limited perceptions, are its masters. With issues such as global warming we stand on the brink of an abyss. We must decide as wisely as we can how to spend our time and money to ensure a sustainable future. If we don鈥檛 undertake research with a clear sense of our limitations and possibilities, and if policy makes promises it can鈥檛 keep, both scientific understanding and global management will suffer.
The best way forward is to remove the notion of cause and effect from policy. Both Hume and Popper advocated the use of probability theory to ascribe degrees of belief, instead of searching for scientific certainty. Rather than trying to establish causation, policy-makers could introduce a scale of increasingly strict preventive measures that depend on the strength of the evidence that some harmful effect will occur. Establishing such probabilities is within the scope of science, and the resulting policy would be clearer and more achievable.
The problem arises from a deeper issue within science itself, so the change must begin there. 杏吧原创s must become more aware of the philosophy underpinning our attempts to understand the world, and make clear to policy-makers and the public what science can and can鈥檛 do. Our future depends on it.