Prudence, Precaution, and Uncertainty: Assessing the Health Benefits and Ecological Risks of Gene Drive Technology Using the Quasi-Integral Parts of Prudence

UNCERTAINTY HAS become a central problem for contemporary decision-making. It is difficult to predict the outcomes of actions and even more difficult to foresee the possibility and effects of rare events. Though considerations of uncertainty and contingency have always had an important place in human action, two aspects of modernity have accentuated their importance.

First, society depends upon complex, interconnected systems in areas such as communications, transport, finance, and medicine, systems that have vastly increased the efficiency of contemporary society but at the cost of increasing fragility through amplification of the effects of small events.¹ A glitch in the trading algorithm of a single firm can send markets plunging, floods in Thailand can bring the global computing industry to a halt, and a disease outbreak in West Africa swiftly threatens New York. Moreover, increasingly complex causal chains make the future effects of actions more opaque to the decision-maker, since it is difficult to predict what will result from any intervention. For example, it is unlikely that U.S. regulators would have let Lehmann Brothers fail in 2008 if they knew that this policy would precipitate a global financial crisis.

A second, related problem rests on the novelty of technological developments, which bring many advantages in their train, but also greater and, to some extent, unknown risks, since no one has ever had experience with these novelties. These new technologies increase dangers of random shocks to the system as they magnify the power of individual actors—a malign hacker, a DIY bioweapons designer, or even a foolish trader can have outsize effects. The unknown, the unpredictable, and the contingent play an ever-larger role due to otherwise beneficial developments in technology and social organization.

Because of these changes, society increasingly focuses on governing risks to health, security, the economy, and the environment.² Regulators, banks, public health officials, and intelligence agencies dig through massive amounts of data collected in the past to generate algorithms to predict future risks. In many cases, these developments are to be commended, since good risk assessment is essential for any action. For example, society needs to know how energy policy might endanger the environment. Yet these efforts can also lead to injustice and their own systemic dangers if policy makers become too confident in their ability to control and predict the future. Because such algorithms are based on past data, they cannot reliably predict the effects of new technologies, nor can they deal with rare, unlikely events that have never occurred before but can have great significance. These “Black Swan” events pose the greatest threat to contemporary complex systems.³

Alasdair MacIntyre used exactly this point to attack the utilitarian managerial ideology that claimed to offer a science of society that could give predictive control to the leaders of industry and government.⁴ MacIntyre argues that such predictive control is impossible because of uncertainties arising from radical innovation, free will, game theoretic considerations, and pure contingency.⁵ He follows Machiavelli in arguing that even with “the best possible stock of generalizations, we may on the day be defeated by an unpredicted and unpredictable counter-example.”⁶ Instead of such a calculative rationality, MacIntyre argues, we should turn to the virtues, especially the virtue of prudence, which offers a more flexible decision-making apparatus grounded in experience, rightly formed desire, and tacit knowledge.

I will argue that current models of the virtue of prudence, at least as developed in the Thomistic tradition preferred by MacIntyre, are vulnerable to the same two problems as algorithmic risk analysis in regard to uncertain, rare events.⁷ First, prudence is also formed in the light of past experiences, so it is vulnerable to the problems of novelty. Second, Thomas Aquinas explicitly says that prudential caution cannot consider rare events, but in complex systems, rare events can be the whole game.⁸ Yet, as MacIntyre argues, the Thomistic system is open to development and modification in the face of new arguments and situations.⁹ In this...