Explanatory exclusion and mental explanation

Abstract

Jaegwon Kim once refrained from excluding distinct mental causes of effects that depend upon the sufficient physical cause of the effect (Kim, 1984). At that time, Kim also refrained from excluding distinct mental explanations of effects that depend upon complete physical explanations of the effect (Kim, 1988, 1989). More recently, he has excluded distinct mental causes of effects that depend upon the sufficient cause of the effect, since the physical cause is individually sufficient for the effect (Kim, 2005). But there has been, to this point, no parallel shift in the explanatory realm, such that distinct mental explanations of effects that depend upon complete physical explanations of the effect are excluded since the physical explanation is objectively complete. In this paper I consider, defend, and apply this update to the principle of explanatory exclusion—an update, which, in the final analysis, demonstrates a significant advantage that non-reductive physicalism has over reductive physicalism.

Keywords:

• Explanatory exclusion
• Jaegwon Kim
• Mental causation

Acknowledgements

I would like to thank two anonymous referees for valuable comments and suggestions. I would also like to thank Neil Campbell for numerous valuable suggestions.

Notes

¹ Here, and throughout this paper, the upper case C stands for the explanans proposition, while E stands for the explanandum proposition. By contrast, the lower case c stands for the causal event, while e stands for the effect.

² Perhaps the most famous historical example is found at the beginning of the Third Book of Isaac Newton’s Principia, where his first Rule of Reasoning states: “We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances” (Newton, 1846, p. 384).

³ Some even suggest that Ockham’s principle is only aimed at epistemic entities, not metaphysical entities (Gauch, 2003, p. 272).

⁴ Indeed, a number of authors highlight the similarities that the argument for causal exclusion has with explanatory exclusion (Fuhrmann, 2002, p. 182; Gibb, 2009, p. 5). Andre Fuhrmann, for example, say that Kim thinks “there is essentially only one exclusion problem which may both be cast in terms of explanation as well as in terms of causation” (2002, p. 184). Kim even goes so far as to blend his two principles together under the heading of causal/explanatory exclusion at times (1989, p. 44; 1993, pp. 281, 291). Not surprisingly, as Gibb points out, numerous critics have assumed the two arguments are the same (Block, 2003; Pereboom, 2002). The closeness of the two doctrines is also borne out in the fact that the principle of explanatory realism says that explanations “track” (Kim, 1994, p. 68) or “mirror” (Kim, 1981, p. 307) objective causal relations. So deep is this assumption that explanations track and mirror causation that Kim sometimes fails to mark a distinction between the lower case c (the cause) and the upper case C (the explanans) (Kim, 1994, p. 58; 1989, pp. 94–95). Kim simply assumes that the explanation will so closely resemble the actual cause that he blurs the distinction at times.

⁵ More fully, all physical effects have complete physical explananda statements. If an effect is physical, it can, in theory, be given a complete physical description. Additionally, all physical explananda statements have complete physical explanantia statements. If there is a physical explanadum statement, it can, in theory, be explained by virtue of a complete physical explanans statement. Thus, all causal relations between physical causes and physical effects have complete physical explanations. The principle of physical explanatory completeness is motivated by considerations motivating the principle of physical causal completeness. Neither reductive nor non-reductive physicalists dispute this argumentation.

⁶ It is possible to argue that, in the event of a competition between a mental explanation and a physical explanation, the mental explanation excludes the physical explanation. This move would require a principle of mental explanatory completeness, according to which the mental explanation is a complete explanation of the causal relation between events. This move would also require motivation for why, in the case of competition, the mental explanation should prevail over the physical explanation of the same causal relation between events. Some attempt to secure the former principle, the principle of mental explanatory completeness, by appeal to the sufficiency of the mental cause for the effect. Physicalists, however, insist that effects have physical causes, which may preclude the sufficiency of the mental cause for the effect. As for the latter, it is common to assume that, in the event of competition, physical causes exclude mental causes, not vice versa. This is once again motivated by the physicalist view that effects must have physical causes. I would like to thank an anonymous referee for raising this concern.

⁷ I would like to thank an anonymous referee for pointing out this possible objection.