Rational Responses to Risk, Paul Weirich. Oxford University Press, 2020, xi + 269 pages.

Abstract

In recent years a growing number of philosophers have started working on normative questions related to what may be called ‘pure’ attitudes risk. Pure attitudes to risk are attitudes to risk that cannot be reduced to attitudes to certain states of affairs, but rather are directed to the risk itself. Although such attitudes have gained much attention by economists, psychologists and philosophers in the past, most (but certainly not all) of this attention was directed at descriptive questions. The current trend in the literature deals explicitly with normative questions. Paul Weirich’s new book constitutes a deep and comprehensive major contribution to this new line of literature. It also constitutes a very unique such contribution. I will point to two different – but related – senses in which this is the case, but before doing so it will be instructive to first cover some necessary background. Although this goes against the spirit of his book (as will soon become clear), in order to understand the differences between Weirich’s account and other contemporary accounts, it will be useful to adopt, at the outset, a characterization of attitudes to risk in terms of preferences over risky options. Consider an agent who faces a decision between two gambles whose possible outcomes are different quantities of some divisible good, G. The two gambles have the same expectation in terms of G, but different variances.1 We can say that the agent is risk-averse with respect to G if she prefers the gamble with the lower variance, risk-seeking if she prefers the gamble with the higher variance and risk-neutral if she is indifferent between the gambles. For example, consider an agent who faces a choice between a certain 100 units of G (gamble A) and a gamble that gives 200 units of G with probability 0.5 and nothing with probability 0.5 (gamble B). A risk-averse agent (with respect to G) prefers A to B, a risk-seeking agent prefers B to A and a risk-neutral agent is indifferent between the two gambles. We can distinguish between three types of explanations for risk-aversion and risk-seeking with respect to G (for convenience let us concentrate on riskaversion, though).2 First, the agent might be risk-averse with respect to G (in the sense explicated above) because she values every additional unit of G in a marginally decreasing (increasing in the case of risk-seeking) way. If the agent