Defending Double Effect

Abstract

This essay defends a version of the Doctrine of Double Effect (DDE) – that is, the doctrine that there is normally a stronger reason against an act that has a bad state of affairs as one of its intended effects than against an otherwise similar act that has that bad state of affairs as an unintended effect. First, a precise account of this version of the DDE is given. Secondly, some suggestions are made about why we should believe the DDE, and about why it is true. Finally, a solution is developed to the so-called ‘closeness problem’ that any version of the DDE must face. 0. One form of deontological ethics involves the so-called Doctrine of Double Effect (DDE). 1 As I shall interpret it here, the DDE is the thesis that there is normally a stronger reason against an act if that act has a bad state of affairs (like an innocent person’s death) as one of its intended effects than if that bad state of affairs is merely one of the act’s unintended effects. In other words, according to the DDE, it is harder to justify an act that has a bad effect if that effect is intended than if it is not intended. Many writers have severely criticized the DDE. These critics include all moral theorists who subscribe to any form of act-consequentialism – since according to act-consequentialism the permissibility of an act is determined purely by the intrinsic values of the available acts’ total consequences, and not by whether any of the act’s effects are intended or unintended. But the critics also include some proponents of deontological ethics, some of whom who accept that the difference between doing and allowing is ethically significant, but reject the DDE’s claim about the significance of the distinction between intended effects and unintended effects. 2 In this essay, I shall argue that these critics are mistaken. The DDE, at least in the version that I have formulated here, is entirely correct. 1. The version of the DDE that I am defending here is not exactly identical to the versions that have been discussed by other philosophers. For example, consider the version of the DDE that is discussed by T. M. Scanlon (2009, 1): The doctrine of double effect holds that an action that aims at the death of an innocent person, either as its end or as a means to its end, is always wrong. There are several differences between Scanlon’s version of the doctrine and the version that I wish to defend here. First, Scanlon’s version condemns all acts that ‘aim at’ the death of an innocent person, regardless of whether these acts succeed in achieving this aim or not. The version of the DDE that I shall defend here, by contrast, concerns only those acts that succeed in realizing the bad state of affairs that they were aiming at. In my view, acts that aim at a bad state of affairs but fail to achieve this aim fall into a somewhat different category – which unfortunately I shall not have time to discuss here. Secondly, the version of the doctrine that Scanlon discusses is narrowly focused on acts that aim at the death of an innocent person. But it seems clear that if this version of the doctrine is true, this will not be because of anything special about deaths in particular; instead it will be because of a fundamental difference between the roles of intended effects and unintended effects 1 The doctrine goes back at least as far as Thomas Aquinas’s discussion of self-defence; see Summa Theologica, IIa IIae, 64, 7. 2 For such deontological critics of the DDE, see especially Judith Thomson (1991 and 1999) and T. M. Scanlon (2009). I have already responded, at least briefly, to their objections elsewhere; see Wedgwood (2011). For this reason I shall focus on other objections here.