Philosophia (2014) 42:363–385DOI 10.1007/s11406-013-9496-4

Counterfactual Causation and Mental Causation

Jens Harbecke

Published online: 2 October 2013© Springer Science+Business Media Dordrecht 2013

Abstract Counterfactual conditionals have been appealed to in various ways toshow how the mind can be causally efficacious. However, it has often been overes-timated what the truth of certain counterfactuals actually indicates about causation.The paper first identifies four approaches that seem to commit precisely this mis-take. The arguments discussed involve erroneous assumptions about the connectionof counterfactual dependence and genuine causation, as well as a disregard of therequisite evaluation conditions of counterfactuals. In a second step, the paper uses theinsights of the foregoing analyses to formulate a set of counterfactuals-based condi-tions that are characterized as sufficient to establish singular causal claims. The paperconcludes that there are ample reasons to believe that some mental events satisfy allthese conditions with respect to certain further events and, hence, that mental eventssometimes are causes.

Keywords Mental causation · Counterfactual causation · Philosophy of mind ·Metaphysics · Causal exclusion · Supervenience

Introduction

Within the contemporary philosophical debate on mental causation1, counterfactualconditionals have been appealed to in various ways to support the hypothesis thatunreduced mental events are sometimes genuine causes of physical events. The main

1For a detailed exposition of the philosophical problem underlying this debate, cf. for example Harbecke2008, ch. 1.

J. Harbecke (�)Philosophy of Science, Witten/Herdecke University, Witten, Germanye-mail: jens.harbecke@uni-wh.de

Received: 8 January 2013 / Revised: 19 August 2013 / Accepted: 29 August 2013

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motivation for these approaches has usually stemmed from the insight that a process,or conserved quantity, theory of causation underlies the many versions of the causalexclusion argument against mental causation (cf. Loewer 2001, 320; for the causalexclusion argument, cf. Kim 1998, 37–38, and Papineau 2002, 17–18). Whilst it isuncontroversial that mental causation cannot be based on the transference of mentalenergy quanta since no such mental energy exists, several authors have proposed that“[t]he trouble [...] can be avoided by [...] rethinking the notion of causation.“ (Baker1993, 91) If genuine causation is analyzable in terms of certain counterfactuals,then, so the idea goes, genuine and unreduced mental causation may be a consistentconcept after all.

One popular line of argument uses a presumed counterfactual dependence of cer-tain physical events on certain mental events as a reliable indicator for a causalconnection (cf. Baker 1993, 93; Loewer 2001, 322f; Loewer 2002, 660f).2 A secondmakes use of a counterfactual transition inference that deduces a causal efficacy ofmental events for those physical events that counterfactually depend on the mentalevents’ physical supervenience bases (cf. Kroedel 2008, 137f; Heil and Mele 1991,68; Horgan 1989, 61; Loewer 2007, 257; Kallestrup 2006, 473). A third first listsreasons for believing in a replacer counterfactual stating that mental events wouldensure the occurrence of certain physical effects even if their actual physical real-izers would not have occurred, and then declares the truth of this counterfactual tomake a positive case for mental causation (cf. Mills 1996, 108f; Pietroski 1994, 358;Kallestrup 2006, 473; Raatikainen 2006, 7; List and Menzies 2007, 11–18). Finally,some authors have discussed a counterfactual test for overdetermination. In light ofthe notorious difficulties to argue positively for mental causation, this test is meant toprove that at least the classical exclusion principle does not make a convincing caseagainst mental causation (cf. Lepore and Loewer 1987, 639; Bennett 2003, 486–89).

It is safe to say that all of these approaches have contributed substantially to thedetailed understanding of the problem of mental causation that philosophy can claimto have today. In particular, the approaches have shed new light on the causal exclu-sion principle as well as the notion of a causal overdetermination of events. Moregenerally, they have shown that different solutions to the problem of mental causationare sometimes influenced by the theories of causality presupposed.

And yet, it appears that some of the detailed accounts developed within the above-mentioned approaches are infected by a tendency to overestimate what the truth ofa counterfactual tells us concerning the causal relation between events. As a result,certain argumentative shortcomings or even fallacies have established themselves in

2A related line of argument claims that, from the standpoint of the interventionist theory of causation, thereare defensible causal models indicating a causal relevance of the mind (Raatikainen 2006, 5–8; Shapiroand Sober 2007, 241; Weslake 2009, 15–18; Woodward 2010, 2011). Since the structural equations usedin such causal models condense sets of counterfactuals (cf. Hitchcock 2007, 501), these approaches beara certain correspondence to the argument mentioned in the text. However, they form a special case asthey are essentially based on the notion of an independent intervention, and as they are not intended tobe reductive theories of causation. Section “Interventionist Causation and C.A.R.E” points out how thesolution developed in this paper relates to the interventionist approaches.

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parts of the debate. In consequence, the actual value of counterfactual analyses for atheory of mental causation has been obscured to some extent.

The aim of this paper is, on the one hand, to locate and analyze some of the argu-mentative shortcomings that have sometimes occurred in counterfactual approachesto mental causation and, on the other hand, to show that a slightly more complexcounterfactual theory than the ones usually presupposed holds the resources for aconceptually transparent and metaphysically plausible model of mental causation.This slightly more complex theory will be based on a set of counterfactual condi-tions described as sufficient, and partly necessary,3 for the identification of causalrelations.

As a first step, Lewis’ well-known counterfactual theory of causation is brieflyreviewed (section “Counterfactual Causation”), before certain fallacies and argumen-tative shortcomings prevalent in the debate on mental causation are made explicit(section “Counterfactual Fallacies”). Afterwards, a set of counterfactuals-based con-ditions sufficient for identifying singular causal relations is developed that seemto ascribe a causal role to mental events (section “A Proposal”). Eventually, it isinvestigated how the attained results relate to an interventionist approach to mentalcausation (section “Interventionist Causation and C.A.R.E”). The paper concludeswith some remarks on the scope and implications of the investigation and points outsome open questions that may be pursued in future research (section “Conclusion”).

Counterfactual Causation

Knowing that a kangaroo’s tail has something important to do with the way it moves,we tend to endorse claims such as: “If kangaroos had no tails, they would toppleover”. Lewis (1973b, c) uses expressions like ‘P �→ Q’ to formalize counter-factual statements of this kind, where ‘P’ and ‘Q’ designate any two first-ordersentences and ‘�→’ is a counterfactual conditional operator. According to Lewis, acounterfactual P �→ Q is true at a world w if, and only if, . . .

“. . . either (1) there are no possible P-worlds (in which case P �→ Q is vacu-ous), or (2) some P-world where Q holds is closer (to w) than is any P-worldwhere Q does not hold.” (Lewis 1973a, 560, minor modifications)

The relation “closer to w” is based on the assumption that all possible worlds areweakly ordered with respect to similarity in local fact and laws of nature. The moresimilar a world is to w, the closer it is to w.

Counterfactual locutions seem well-suited to express our intuitions about causalrelationships. When we recognize an event as a cause of another event, we typi-cally accept a claim such as “Had the cause not occurred, the effect wouldn’t have

3“Partly necessary”, because one of the conditions fails to be satisfied in cases of genuine overdetermina-tion and pre-emption. These exceptional cases require a detailed discussion that goes beyond my presentaim, but cf. Bennett (2003).

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either”. Lewis (1973a, 1979, 1986, 2000) exploits this fundamental insight for thedevelopment of a theory of causation itself. The author first specifies a counterfactualdependence between two events E1 and E2 over the truth of the two counterfactu-als E1 �→ E2 and ¬E1 �→ ¬E2

4 (note that the above-mentioned truth conditionsfor counterfactuals imply that the former conditional is trivially true if E1 and E2 areactual events). Since, according to Lewis, counterfactual dependence implies causaldependence and “[c]ausal dependence among actual events implies causation . . .”(Lewis 1973a, 563), the truth of these counterfactuals is sufficient for a causal relationbetween E1 and E2.

As seductively simple and as adequate for many paradigm cases this analysismay be, it requires some caveats. One well-known difficulty concerning the infer-ence from mere counterfactual dependence to causation is grounded in the fact thatcounterfactual dependence between events is both sometimes too restrictive andsometimes too permissive to account for causal relationships.5

Furthermore, the specification of the truth conditions for causally interpretablecounterfactuals involves some important constraints on the worlds considered for theevaluation. In particular, if events are modally fragile entities then the Lewis seman-tics for counterfactuals turns out almost useless for identifying causal relationships.The point is that, by Lewisian standards, the closest world in which an actual eventE1 does not occur is almost always one in which E1 is replaced by an event E ′

1 whichresembles E1 not completely but almost perfectly, and which has the same effect E2 asthe actual E1. The reason is that all closest {¬E1, E ′

1, E2}-worlds have a larger overlapin laws and particular fact with the actual world than the closest {¬E1,¬E2}-worlds.Lewis’ theory still does not yield false interpretations, as in his view counterfactualdependence is sufficient, but not necessary, for causation. However, the theory turnsout to be almost empty: almost no effect in the actual world counterfactually dependson its causes. And counterfactuals are useless for detecting causal relationships.

To counter the emptiness problem, Lewis has introduced a further constraint onthe evaluation of causal counterfactuals that has sometimes been described as a “banon replacement” (Bennett 2003, fn. 21):

“When asked to suppose counterfactually that E1 counterfactually that E1 doesnot occur, we do not really look for the very closest possible world where E1’sconditions of occurrence are not quite satisfied. Rather, we imagine that E1 iscompletely and cleanly excised from history, leaving behind no fragment orapproximation of itself.” (Lewis 2000, 190; minor modifications; cf. also Lewis1986, 211)

4More precisely, the counterfactuals should be written as “O(E1)�→O(E2)” and “¬O(E1)�→ ¬O(E2)”,where O(E1) and O(E2) are intended as first-order sentences describing events E1 and E2. Throughoutthe paper, we avoid this notational complication and leave implicit the important distinction betweenexpression and referent.5Cases showing that counterfactual dependence is sometimes too restrictive to count as a criterion forcausation are overdetermining, preempting (Lewis 1973a, 567), and trumping (Schaffer 2000) causes. Acase showing that counterfactual dependence is too permissive a criterion is the “problem of large causes”discussed below.

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The question is, of course, what “cleanly excised” should mean precisely. Oneinterpretation would insist that the relevant closest ¬E1-worlds can still be worldsin which E1 is replaced by an event E ′

1. It’s just that E ′1 must always be sufficiently

different from E1. This move in turn leaves open what “sufficiently different” couldmean in this context. If the answer is “among other things, E ′

1 should never be acause of E2”, then the counterfactual theory of causation becomes circular. However,a circular criterion is inacceptable for it would jeopardize the reductive aims of thecounterfactual theory of causation.

Bennett (2003, 482) has argued that there is only one interpretation of the notion of“clearn excision” that is both non-circular and adequate for Lewis’ purposes. Accord-ing to this idea, if you imagine an event E1 gone in a non-E1 world w¬E1 , “[y]ousimply snip it away as though you had a metaphysical hole-puncher.” The same ideaoccurs in Collins et al. (2004, 21) when the authors ask whether cleanly excisingcould mean to “[f]ill the spacetime region in which [the event referred to] occurs withvacuum?”

My impression is that something along the general proposal of Bennett andCollins et al. is in fact the only non-circular strategy for making sense of the ideaof cleanly excising an event from history. For the remainder of the paper, I willtherefore presuppose precisely this: In the non-E1 world w¬E1 used to evaluate, forinstance, a counterfactual of the form ¬E1 �→ ¬E2, the space-time region of w¬E1

corresponding to the region occupied by E1 in wE must be empty.6

A further constraint needed for causal interpretations of counterfactuals is the fol-lowing. Note first that counterfactuals are variably strict conditionals in the sense thattheir antecedents cannot be salva veritate supplemented by further conjuncts (Lewis1973b, 13–19). However, if, for instance, the event Ek chosen for the supplementa-tion is remote enough from E1, the supplementation will always preserve the truth ofthe counterfactual. Suppose, for instance, it is true that, had John’s being drunk (callit “E1”) not occurred, the car accident (call it “E2”) would not have occurred either.Then most likely it will also be true that, had John’s being drunk and the implosionof distant planet (call it “Ek”) not occurred, the car accident would not have occurredeither. In other words, both the counterfactuals E1&Ek�→ E2 and¬(E1&Ek)�→ ¬E2will likely turn out true, and Lewis’ definition of causal dependence will be satisfied.

The question is what this observation implies. A straightforward interpretationwould be that, according to Lewis’ theory, the referent of the complex statement“E1&Ek” is a cause of E2. However, since what is happening with a distant planethas at least no immediate impact on what happens on earth, the referent of “E1&Ek”consisting of John’s drunkenness and the implosion of some planet should not turnout to be a cause of E2–it just contains too much irrelevant stuff. This implies thatLewis’ criteria are not sufficient for causation.

6It may be argued that this interpretation has bizarre consequences. For instance, the closest world whereWW2 didn’t happen would be one where the space-time region actually occupied by WW2 is empty.Surely this isn’t the most similar world where WW2 doesn’t happen. However, the point remains: If acircular criterion is to be avoided, the most similar world where WW2 doesn’t happen cannot automaticallybe used for evaluating the relevant counterfactuals for a causal analysis. It must indeed be a non-WW2world that may not be the closest non-WW2 world, but that contains the mentioned big void.

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A counterargument to this conclusion may be that, since ¬(E1&Ek) is true if eitherE1 or Ek is false, a closest non-Ek world that is a E1 world may sometimes make¬(E1&Ek)�→ ¬E2 false, and so the problem is less radical than suggested above.To counter this objection, note that we encounter the problem of large causes alreadyif only some antecedent supplementations preserve the truth of the counterfactual.Lewis’ theory will characterize overly large events as causes in this case.

Another interpretation would be to infer that no counterfactuals with a complexantecedent are causally interpretable, perhaps because there are no such things as“complex events” that conjunctions of singular statements would pick out. Con-sequently, it may seem that Lewis’ theory can be saved from establishing falsecausal claims. However, this interpretation overlooks the fact that sometimes sim-ple antecedents of true counterfactuals refer to much-too-large events relative to theevents referred to by their consequents. For instance, take Eu to refer to the completestate of the universe preceding E2. Then the counterfactual ¬Eu �→ ¬E2 will cer-tainly be true. However, it is highly counterintuitive to characterize a complete stateof the universe as a cause of E2. It may contain causes of E2, but Eu itself mostly con-sists of stuff that is causally irrelevant to E2. Describing Eu as a cause of E2 wouldtherefore be quite extravagant.

Drawing these various threads together, we are driven to conclude that theantecedent of a counterfactual needs to be minimized, or adjusted, in some way ifthe counterfactual should be causally interpretable.7 As we will see, this “problemof large causes” has important consequences for certain counterfactual approaches tomental causation as well.

Counterfactual Fallacies

Suppose that a (fine-grained8) mental event Mc occurring at time t1 has a candidateeffect M*e occurring at time t2. Suppose further that Mc supervenes on a specificneural event Pc which has a specific neural effect P*e at t2. Certain further consider-ations then suggest that P*e is the supervenience base of M*e. Finally suppose thatM is not identical to P and M* is not identical to P* (and, hence, that neither Mc andPc nor M*e and P*e are identical events). The general scenario resulting from theseassumptions is often illustrated by pictures similar to Fig. 1 (cf. LePore Loewer 1989,180; Kim 2003, 159; Gibbons 2006, 79; Kallestrup 2006, 463; Sachse 2007, 52).

One question central to the debate on mental causation based on the scenario ofFig. 1 is how it should be possible that Mc is a cause of M*e given that the occurrenceof P*e is already wholly sufficient for M*e. It seems that, if Mc should be a cause ofM*e, then it must cause P*e (cf. Kim 2003, 165). However, by our hypothesis, P*e is

7A more precise definition of what such a “minimization”, or an “adjustment“, could be is given in section“A Proposal”.8For details on the fine-grained ontology of events, cf. Kim 1973. The remainder of the paper implicitlyassumes that the object and time specification that a fine-grained event contains assigns a determinedspace-time extension to every event. In our example, c and e are taken to be objects and M, M* are taken tobe mental properties had by these objects, and P, P* are taken to be physical properties had by the objects.

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Fig. 1 The problem of mentaldownward causation

already caused by Pc rendering Mc causally redundant. This apparent redundancy ofmental causes may induce doubts as to whether mental events can be genuine causesat all.

The conclusions suggested by the scenario illustrated by Fig. 1 have struck manyauthors as unsatisfactory. To block the redundancy of mental causes, some havealluded to the seemingly obvious truth of certain counterfactual conditionals in orderto argue either for a genuine causal role of mental events, or at least against acompetition of mental and neural causes of neural effects.

Most of these argumentative strategies can be subsumed under one of the threeapproaches mentioned in section “Introduction”. Unfortunately, and as already adum-brated above, the viability of some of these strategies is questionable on grounds ofthe counterfactual theory of causation itself. The trouble mostly stems from a disre-gard of the constraints on causally interpretable counterfactual conditionals discussedin section “Counterfactual Causation”. Some of these problematic argumentations arereconstructed in the following paragraphs. The arguments are presented as instruc-tions for committing a fallacy and therefore more or less as caricatures of originalproposals.

Fallacy 1: “Point out that, whilst our best science gives us reason to believe inthe counterfactual ¬Pc �→ ¬P*e, our explanatory practices and common senseunderstanding strongly suggests the truth of the counterfactual¬Mc �→ ¬P*e aswell. From the truth of the latter counterfactual infer the claim that mental eventssometimes are causes of neural, or generally physical, events.”9

9This argumentative strategy is reflected by Baker (1993) who claims that satisfaction of the two Lewiscounterfactuals is sufficient for causation (cf. op. cit., 93). As the author takes at least some mental eventsto satisfy these counterfactuals with respect to certain physical events “. . .the problem of mental causa-tion just melts away.” (op. cit., 93). A similar view is expressed by Loewer (2001, 2002): “Suppose that¬Mc �→ ¬P*e so Mc is a putative cause of P*e. . . . The non-reductive physicalist holds that there aremental events Mc that are putative causes that are not pre-empted by events that they themselves don’tpre-empt.” (2002, 660; minor modifications). In the author’s view, this insight proves that at least somemental events are causes.

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Since Mc and P*e were presumed to be actual events, the counterfactual Mc �→P*e is trivially true and the question about a causal connection between the twoevents will focus on the conditional mentioned by Fallacy 1. However, as the dis-cussion of the “problem of large causes” highlighted, the truth of such a pair ofcounterfactuals says very little about a causal relationship between the two events Mcand P*e. The reason is that, in principle, the conditional ¬Mc �→ ¬P*e could betrue even if Mc were a “very large” event that contained an immense amount of detailsuch that most of what it consists of has no causal connection whatsoever to P*e (pre-sumably in this case also Mc’s supervenience base Pc will be “too large” with respectto P*e without this jeopardizing the truth of the counterfactual ¬Pc �→ ¬P*e).Consequently, inferring a causal relationship from the mere counterfactual depen-dence without ensuring that the antecent of the relevant counterfactual is minimizedis at least highly problematic.

Fallacy 2: “Point out that our best science gives us reason to believe in the coun-terfactual ¬Pc �→ ¬P*e (causation) and that broader philosophical argumentsstrongly support a modal claim of the form �(¬Mc → ¬Pc) (supervenience).From these two assumptions infer ¬Mc �→ ¬P*e and argue that the truth ofthis counterfactual indicates that mental events sometimes are causes of neural, orgenerally physical, events.”10

Fallacy 1 and Fallacy 2 are closely related. The difference between the twoconsists in the fact that the former takes the counterfactual ¬Mc �→ ¬P*e tobe independently supported by common sense or by quotidian explanatory prac-tice whilst the latter infers this counterfactual from presumably less problematicassumptions.

As it turns out, the inference from ¬P ∗e �→ ¬P*e and �(¬Mc → ¬Pc) to¬Mc �→ ¬P*e is invalid (Lewis 1973b, 32). However, even if it could be arguedthat, in the present case, truth is preserved (because the special cases responsible forthe invalidity of the corresponding argument scheme can be ruled out), the truth ofthe counterfactual pair ¬Mc �→ ¬P*e and Mc �→ P*e still says little about acausal relationship between the events referred to. Hence, unless more details aregiven about the structure of the antecedent of the counterfactual, Fallacy 2 suffersfrom the “problem of large causes” as well.

Fallacy 3: “Point out that, since supervenience implies �(P c → Mc), the coun-terfactual Pc&¬Mc �→ P*e comes out vacuous, so that Mc is actually requiredfor Pc to cause P*e. Point out further that there are good reasons to believe inthe non-vacuous truth of the counterfactual Mc&¬Pc �→ P*e, so that Mc’soccurence will be enough for P*e to occur. Argue that the reason for this lies in

10This line of thought is explored by (Loewer 2007) when he claims that “. . .[non-reductive physicalism]holds that [due to supervenience] the connection between Pc and Mc is one of metaphysical not merelynomological necessitation. In the most similar world at which ¬Mc it is also ¬Pc since there is noquestion of “breaking” the metaphysical connection. So in this situation ¬Mc �→ ¬P*e may well betrue” (op. cit., 257; minor modifications). For slightly less explicit versions of the line of argument, cf.Kroedel (2008), Heil and Mele (1991, 68) Horgan (1989, 61) and Kallestrup (2006, 473).

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the fact that, in the closest ¬Pc world, P will be replaced by some other realizerproperty P ′ of M resulting in an event P ′c that subvenes Mc and that causes P*e.Claim that these observations together provide ample reason to believe in a causalrelation between Mc and P*e.”11

The vulnerable spot of this style of argument becomes obvious once the above-mentioned interpretation of a “clean excision” of an event from history is taken intoaccount. The point is that the ¬Pc-world used for the evaluation of the counterfactualMc&¬Pc �→ P*e cannot be a world where Pc has a replacer P ′c if the counter-factual is intended for causal interpretation. Rather, in the ¬Pc-world, Pc must becleanly excised. And since the non-temporal determination relation of supervenienceis plausibly interpreted as implying that the space-time region occupied by an eventis always contained in the region of any of its supervenience bases, then, if Pc isexcised from history, so is Mc. Consequently, if evaluated under the mentioned con-straints, the complex counterfactual Mc&¬Pc �→ P*e is vacuously true contraryto the above contention. Its vacuous truth, however, can hardly form a basis for adefensible claim about a causal relationship (cf. also Bennett 2003, 481ff).

Fallacy 4: “Point out that, for Mc and Pc to causally overdetermine P*e in aproblematic way, both the following counterfactuals must be non-vacuously true:Mc&¬Pc �→ P*e and Pc&¬Mc �→ P*e. Then argue that supervenienceimplies that �(P c → Mc), which renders the antecedent of the latter counterfac-tual non-satisfiable. Argue that, consequently, at least the second counterfactualis vacuous and there can be no problematic causal overdetermination with onepotential cause excluding the other.”12

As mentioned in the analysis of Fallacy 3, if one out of Pc and Mc is excisedfrom history, so will be the other. This immediately implies that both counterfactualscome out vacuous if they are evaluated in a way relevant for causal claims. Sincethe vacuity has little to do with a relation between Pc and Mc apart from their co-instantiation, it seems at least premature to infer a non-competition of the two eventsand to dismiss the tenacious impression that Pc is still better suited as a cause ofP*e.

What these fallacies show at minimum is that counterfactual conditionals must betreated with great care if they are to be of any value for a defense of a causal effi-cacy of unreduced mental events. The remainder of this paper focuses on what couldbe meant with “great care” here. The aim will be to specify a set of counterfactualconditions that are sufficient for identifying causal relationships. These conditionscarefully circumvent the “ban of replacement” and the “problem of large causes”.

11This style of argument is clearly pursued by Mills (1996, 107–109) and List and Menzies (2007, 18).Slightly less explicit versions are found in Pietroski (1994, 358), Kallestrup (2006, 473), and Raatikainen(2006, 7).12An argument of this kind is at the core of Bennett (2003). A related line of thought seems to be presentin LePore and Loewer (1987, 639).

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My claim will be that mental events sometimes satisfy these conditions with respectto certain other events and that, hence, mental events sometimes are causes.13

A Proposal

A constraint necessary for counterfactuals to be causally interpretable was tentativelydescribed in section “Counterfactual Causation” as a “minimization”, or “adjust-ment”, of the antecedent. It was pointed out that Fallacy 1 and Fallacy 2 suffer froma disregard of this constraint. It follows that, in order to determine which counterfac-tuals are causally interpretable, a selection strategy that isolates those counterfactualswhose antecedents refer to events that are “just of the right size” for the eventsdescribed by their consequent is needed. The intuitive notion of the “right size” israther elusive, of course. Notwithstanding, the two conditions below try to capturethe idea formally.

Before these conditions are formulated, it is important to make explicit the con-ceptual frame within which they are developed. The frame is constituted by certainassumptions that have a tradition either in the counterfactual theory of causation orin the debate on mental causation. Some of them were implicitly presupposed inFallacies1-4. Others occur less obviously in the debates on mental causation andcounterfactual causation, but many positions developed in these are bound to endorsethem nevertheless. The assumptions are the following:

Firstly, any event occupies a sufficiently determinate space-time region. This claimis at the heart of Kim’s fine-grained model of events (cf. fn. 8 above). It is widelypresupposed in the debate on mental causation as mental events without a spatio-temporal dimension could hardly have impacts in space and time.

Secondly, for any two events P and Q, there is at least one event R occupying aspace-time region that is the fusion of the regions occupied by P and Q. Since suchan event is nothing more than the two events fused, it is ontologically innocent.14 Thisidea of an unrestricted fusion–at least of objects–has a tradition in Lewis himself.Discussing a fusion of a trout and a turkey, the philosopher says that “(...) it is neitherfish nor fowl, but it is nothing else: it is part fish and part fowl.” (Lewis 1991, p. 80).In Lewis’ view, “mereology is innocent” (op. cit., p. 87).

13Note that the theory presented in section “A Proposal” mirrors an influential idea that Yablo (1992)has elaborated long ago. However, note also that the former theory differs from the latter substantially. Inparticular, the theory defended here can bypass Yablo’s essentialist framework. Furthermore, the proposedformulation of the four counterfactual conditions differ from Yablo’s in important details. Finally, it is notclear that Yablo would agree with the parallelist picture that the theory defended here suggests. I leave itto the reader to analyze these differences in more detail.14To make this assumption plausible to some extent, consider the fact that, if a world contains the twoevents of “Jack’s jumping into the pool” and of “Jill’s jumping into the pool”, then that world also seems tocontain the event of “Jack’s and Jill’s jumping into the pool”. This pattern seems to generalize. One mightargue, of course, that event fusion should be restricted in some way, e.g. to spatially contiguous events.For the current project, it is sufficient to assume that there is a large number of fused events, whatever therestrictions on fusion.

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Taking innocent event fusion as a starting point, we describe R as “being partlyfused” from an eventP if P’s region is a proper part of R’s region, and we describe Ritself as “being wholly fused” from an event P if P’s region is identical to R’s region(note that we do not require that R be identical to P in this case). A corollary of theabove assumption combined with this definition is that, if an event P is partly, orwholly, fused from an event Q, then Q occupies a space-time region that is containedin the region occupied by P .

Thirdly, if an event P contains irrelevant detail relative to a given effect, then Pis at least partly fused from an event Q that contains all and only the detail irrelevantfor the given effect. “Irrelevant detail” is understood here as some substantial surplusin contrast to a mere aspect of an event. For instance, my typing these words is acause of the mental state of the reader of this paper at the very moment she is readingit. The speed of my typing, however, is causally irrelevant for the mental state: thewords will be just the same, and read at just the same time, however quickly I type.But even if my typing fast is causally irrelevant with respect to the mental state, thereis no surplus event Q (relative to the typing P) that contains only my typing fast.The reasons is that P and Q clearly overlap in this case. This shows that not anythingirrelevant about an event makes a surplus event.

An example of an intuitive genuine surplus event within a cause was presented,for instance, in the complete-state-of-the-universe case from section “CounterfactualFallacies”. In this case, the “irrelevant stuff” contained in the complete universe statewas constituted of a vast number of objects instantiating properties at times. In otherwords, the irrelevant surplus was a set of more specific events contained in the com-plete state of the universe. The third assumption just mentioned claims that thesekinds of irrelevant further subevents can always be fused into a unitary event in thesense of innocent event fusion.

Fourthly, events can be causal competitors for some effect in the problematic senseonly if they are both located roughly in the same space-time region and related bysupervenience. Being related by supervenience can mean to supervene, to subvene,or to both supervene and subvene (i.e., being identical). This claim is not alwaysmade explicit by the authors discussed in section “Counterfactual Fallacies”. Butsince they all use a diagram of the form of Fig. 1 as a starting point, the assumptionquite obviously plays an important background role within the debate. Note that thisfourth claim still allows for the existence of non-identical events in the same regionthat are not related by supervenience.

To repeat, these four assumptions have a tradition either in the counterfactualtheory of causation or in the debate on mental causation. None of them is entirelyuncontroversial. However, since my concern here is to make sense of mental cau-sation within the counterfactualists’ camp, it suffices to point out that a majority ofauthors participating in the debate would endorse them.

Contingency and Adequacy

To fix the counterfactual theory of causation so that it can avoid the problems men-tioned in section “Counterfactual Causation”, say that for any two events R and P ,R ⊆ P (resp. R ⊂ P) holds if, and only if, P is either partly, or wholly, fused

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from R (resp. P is partly, but not wholly, fused from R). Then the following twoconditions adjust the size of the candidate causes with that of the effect.

Contingency: Q is contingent upon P if, and only if, for all R such that R ⊆ P :R �→ Q and ¬R �→ ¬Q.

Adequacy: P is adequate for Q if, and only if, for no R such that P ⊂ R : Q iscontingent upon R.

Contingency says that, if event P had not occurred, event Q had not occurred, andthe same is true of all events R that partly, or wholly, fuse P . The assumption under-lying this condition is that any genuine cause is such that everything contained in itis necessary for its being the cause it is. Removing any of its necessary constituentswill lead to a non-occurrence of the effect.15 Contingency is clearly not satisfied bythe counterfactual “Had John’s being drunk and the implosion of a distant planetnot occurred, the car accident would not have occurred either” (where the “and” isnow intended as indicating fusion), since, by our above hypothesis, the counterfac-tual “Had the implosion of a distant planet not occurred, the car accident would nothave occurred either” is false. This is as it should be.

However, notice that, if John’s being drunk is itself a fused event and if, as we saidabove, everything contained a genuine cause is necessary for the effect’s occurrence,there will be counterfactuals citing the car accident in their consequent that cite intheir antecedent an event that partly fuses John’s being drunk. In other words, Con-tingency may exclude many events that are “too large” to be candidate causes of theeffect in question, but it does not exclude events that are intuitively “too small” to begenuine causes of a relevant effect. To exclude these “too small” events, Adequacysays that no event partly fused from P fulfills the contingency condition with respectto Q. In this way, Adequacy defines an upper bound of Contingency.

In short, Adequacy and Contingency capture the idea of a spatiotemporal adjust-ment, or a “minimization”, that in section “Counterfactual Causation” was describedas necessary in order to avoid, among other things, the problem of large causes.

The crucial question is, of course, what conclusions these two conditions implyfor cases of mental causation as the one illustrated by Fig. 1. To answer it, assumethat Mc is a prototypical complex mental event, such as an event consisting of, orfused from, Mc′: the representation of a glass, and Mc′′: the desire to lift the glassup. Assume further that Mc causes another mental event M*e, which is the desire toextend one’s arm forward towards the glass (i.e., both Mc and M*e are mental events).Finally, assume that the representation and desire of Mc are realised in different brainregions, the visual cortex and the insula say, so that they do not overlap spatiotem-porally in a substantial way. Perhaps M*e is then realised in the motor cortex. In thiscase, Mc would pass the Contingency test with respect to M*e as, by hypothesis, thecounterfactuals Mc �→ M*e, ¬Mc �→ ¬M*e, Mc′ �→ M*e, ¬Mc′ �→ ¬M*e,Mc′′ �→ M*e, and ¬Mc′′ �→ ¬M*e are satisfied.

15This assumption corresponds in some way to a minimality constraint that is familiar from regularitytheories of causation (cf. Mackie 1974, 62; Baumgartner 2008, 330).

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However, an event Mc# fused from Mc and the auditory representation of a black-bird’s call realised in the left Heschl’s gyrus − call it Mc′′′−, would most likely failthe contingency test with respect to M*e, since merely hearing the bird’s call shouldhave no positive or negative influence on the occurrence of M*e (in normal agents atleast). Hence, Mc# �→ M*e, ¬Mc# �→ ¬M*e, Mc �→ M*e, ¬Mc �→ ¬M*ewould be satisfied, but ¬Mc′′′ �→ ¬M*e would be false, and Contingency fails.The explanation for this fact would be analogous to the case of John: Mc# containsirrelevant stuff and is therefore not the genuine cause of M*e.

If we also assume that, for the occurrence of the desire to extend one’s arm for-ward towards the glass, nothing else is causally required than the representation ofthe glass and the desire to lift the glass up16, then Mc also satisfies Adequacy withrespect to M*e. Any event “larger” than, and partly fused from, Mc would containirrelevant detail relative to M*e. However, for instance, Mc′, the representation of theglass, does not satisfy Adequacy with respect to M*e as Mc is partially fused fromMc′ (or Mc′ ⊂ Mc) and Mc satisfies Contingency with respect to M*e. Again, theexplanation would be analogous to John’s case. Just like the road’s being wet is justa partial cause of John’s accident (assuming that John’s being drunk and the road’sbeing wet was a sufficient and complete cause of the accident), Mc′ is at best a partialcause of M*e, but not its genuine cause.

These observations about the satisfaction of Contingency and Adequacy of Mcwith respect to M*e may already lead us to conclude that Mc is in fact a cause ofM*e. Mc actually satisfies two counterfactual conditions relative to M*e, which theinvestigation into Fallacies 1-2 suggested as necessary for (non-preemptive) causa-tion. The next subsection argues, however, that Contingency and Adequacy are notyet sufficient criteria of causation.

Requiredness and Enoughness

By the initial hypothesis, the mental event Mc supervenes on the physical eventPc. Hence, by the fourth assumption made explicit at the beginning of section “AProposal”, the two events can compete causally only if they also occupy the sameplace and time. Given what we said about Mc before, Pc can be thought of as a com-plex neural event fused from the events Pc′, a particular activity within the visualcortex, and Pc′′, a particular activity in the insula say. Since Mc satisfies Contingencyand Adequacy with respect to M*e, so will Pc: There is no subevent partially fusingPc that is redundant with respect to M*e. But also Pc secures the occurrence of Mcand, therefore, of M*e.

In the same way, Mc satisfies Contingency and Adequacy with respect to P*e, theactivity in the motor cortex realising the desire to extend one’s arm forward towardsthe glass. If Mc or any of its fusing parts is not realized, also P*e will not occur.

16If in addition to Mc′ and Mc′′ perhaps certain other mental events in different brain regions wererequired for the occurrence of the desire to extend one’s arm forward towards the glass, then we could fuseall of these together with Mc′ and Mc′′ into a further event Mc+ which would then satisfy Adequacy withrespect to M*e.

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Moreover, there is no event occupying a larger spacetime than Mc that does not havea redundant part with respect to P*e so that Adequacy is satisfied by Mc relative toP*e as well.

It follows that, if Contingency and Adequacy would be all there is to causation,then both Mc and Pc would be causes of both M*e and P*e, and the alleged problemillustrated by Fig. 1 would disappear. There would be no reduncancy of Mc withrespect to, for instance, P*e. Both Pc and Mc would be full and genuine causes ofP*e.

However, strong intuitions suggest that Contingency and Adequacy cannot beeverything there is to causation between events. Pc seems intuitively better suitedfor causing P*e than Mc, no matter what the counterfactual conditions made explicitso far tell us. But why is that so? It seems that, when we search for causes of agiven event, we tend to isolate events that display a similar degree of detail as theeffect. And that is so because causation in fact only happens between events that arecomparably specific.

In the example above, P*e, which was taken to realize the desire to extend one’sarm forward towards the glass, was assumed to be a specific kind of activity of themotor cortex (plus perhaps further neural activities). A candidate cause of such anevent may be a particular kind of activation of the visual cortex and of the insula.The causes and the effects both involve certain trains of electric signals, they involveentities of the same size, and they display a similar general neural network structure(cf. also section “Counterfactual Fallacies”, where I presumed Pe and P*e to be twovery specific neural events). It is therefore natural to view them as stages in the samecausal process. The mental event of a desire to lift a glass which is being representedcan impossibly display a comparable specificity. And this is where the root of thedistinction between Mc and Pc relative to P*e lies.

Some authors have made the same point by emphasizing a claim about the multiplerealizability of macroevents such as Mc. According to this idea, a mental property Mis often realizable not only by a single property P but by a number of further neuralproperties P1, P2, . . . , Pn as well. However, when an event instantiates any one ofthese neural properties, it should not be expected to be followed always by an eventinstantiating the property P*. That is, events such as P1c1, P2c2, . . . , Pncn shouldbe expected to induce different effects P1

∗e1, P2∗e2, . . . , Pn

∗en as well, such thatP1c1 induces P1

∗e1, P2c2 induces P2∗e2 and so on. It follows that the occurrence of

Mc induces either the occurrence of some event involving property P ∗, or P1∗, or

P2∗, . . . , orPn

∗. But it does not secure the occurrence of a single member of this list,such as P ∗.

Consequently, the event Mc is never sufficient for the occurrence of a particularevent instantiating the property P* even in the relevant circumstances (where thecircumstances do not include Pc, of course, as by supervenience, if the circumstanceswould include Pc, they would include Mc as well). It is only sufficient for such aspecific event if its realizer happens to be Pc, which − given multiple realization − isa contingent fact. Again, it is due to its specificity that Pc is a better candidate causeof P ∗e than Mc.

The question is whether these intutions can be transformed into explicitly formu-lated criteria that in conjunction with Contingency and Adequacy are both necessary

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and sufficient for a causal relation between two events. The following two conditions,which we name Enoughness and Requiredness, are intended to achieve preciselythis (the relation ‘. . . � . . .’ is intended as ‘. . .is a supervenience base of. . .’, and‘. . . � . . .’ is intended as ‘. . .is a supervenience base of, but not identical to,. . .’):

Enoughness: P is enough for Q if, and only if, for all R such that R � P it is thecase that: R �→ (¬R �→ ¬Q) and ¬R �→ (R �→ Q).

Requiredness: P is required for Q if, and only if, for all R such that P � R it isnot the case that: R is enough for Q.

To see how these two conditions isolate Pc, in contrast to Mc, as the gen-uine cause of P ∗e, suppose that a sequence of actual17 non-identical candidatecauses < E1, E2, . . . , Ek, . . . , En−1, En > occurs in a particular space-time regionsuch that each event Ei is a supervenience base of an event Ej if i < j , wherei, j = 1, 2, . . . , k, . . . , n − 1, n.18 Suppose further that a specific event Ek in thissequence does, and all events supervening on Ek do not, display a comparable degreeof specificity with respect to a given effect event E*.

Now consider Enoughness. Since all events in the sequence are actual events, thecounterfactual R �→ (¬R �→ ¬Q) collapses into the counterfactual ¬R �→¬Q, which expresses the familiar mere counterfactual dependence already made arequirement by Contingency. The second counterfactual first leads us from the actualworld that we may call ‘@’ to a world in which the candidate cause R is cleanlyexcised. The counterfactual then asks whether − from the perspective of this world− the candidate cause R, if it were to occur, would secure the occurrence of Q,which is the effect in question. In other words, this counterfactual requires us to skipa number of worlds w1, w2, w3, . . . , wn until we reach a world wn+1 in which R isexcised from history. From that world, we search for the next world, in which R doesoccur. Most likely, this will be the last world that we skipped, namely wn.

The point is now that, even if wn+1 cannot be a world in which an event replacingR or any of its supervenience bases can occur, wn can still be such a world withoutviolating the “ban on replacement”. And in fact, the farther we depart from the actualworld, the greater the chances that the supervenience base of the candidate causeR will be changed. Consequently, in almost all cases19 world wn will in fact be aworld in which the supervenience bases of R will be different ones than in @. Thisin turn implies that in almost all cases, if the effect Q displays a higher degree of

17Since discussions of mental causation usually focus on actual events, we spare an explanation of howconditions Enoughness and Requiredness extract a genuine cause of a given non-actual possible effectfrom a sequence of co-instantiated non-actual possible candidate causes. However, the explanation wouldproceed analogously to the one in the text.18Note that, with the fourth principle introduced at the beginning of this section, we ensure that there is noevent inhabiting the mentioned space-time region that is not contained in the sequence (unless it does notcausally compete with any event in the sequence).19That this will be so in “almost all” cases is is a strong assumption that I leave undefended here due tolack of space. It should be noted, however, that it follows from the plausible assumption that for any twonon-identical events P and Q occurring at a world w such that P is a supervenience base of Q, the closest¬P world will almost always be closer to w than the closest ¬Q world.

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specificity than the candidate cause R, Q will not occur in wn and the correspondingcounterfactual ¬R �→ (R �→ Q) will be false. Figure 2 illustrates the case forevent Ek and its supervenience base Ek−1 (the effect in question E* is only implicitlymentioned; depending on whether it displays the same degree of specificity as Ek ,resp. Ek−1, it will occur, resp. will not occur, in wn).

If these assumptions are roughly correct, from the ordered set of coincident events< E1, E2, . . . , Ek, . . . , En−1, En >, only the members of the set < E1, E2, . . . , Ek >

will satisfy Enoughness with respect to E*. All that Requiredness then does is toidentify the upper bound of the sequence of the remaining candidate causes, which inour example is Ek . In other words, even if all supervenience bases of Ek are causallysufficient for the effect E* (in the sense of Enoughness), only Ek satisfies all fourconditions with respect to E* and, hence, can be declared a genuine cause of E*.To summarize, what Enoughness and Requiredness do is to isolate precisely thatevent from a number of coincident20 events that in all worlds relevantly close to theactual world is specific enough, but not excessively specific, to secure the effect’soccurrence. The claim is, of course, that the two conditions give a precise analysisof the intuition that not all events coinciding with a genuine cause of a given effectshould be considered genuine causes of that effect.

Applying C.A.R.E.

By applying the four conditions to the scenario sketched by Fig. 1, we get the fol-lowing results. By our hypothesis, the two coincident events Mc and Pc both satisfyContingency and Adequacy with respect to P ∗e since they occupy a space-timeregion “of just the right size” with respect to P ∗e.

However, also by the hypothesis illustrated by Fig. 1, Pc will constitute the upperbound of all events satisfying Enoughness since Fig. 1 does not graphically referto any further events supervening on Pc other than Mc. Hence, Pc also satisfiesRequiredness with respect to P ∗e. At this point the intuition that Pc is still a moresuitable candidate cause of P ∗e than Mc has been given a precise explication. To besure, Mc does satisfy certain counterfactual conditions with respect to P ∗e and it iscausally relevant for P ∗e in a weak sense, accordingly. However, it would be a mis-take to conclude on the basis of this observation already that Mc is a genuine causeof P ∗e, as it was done in Fallacy 1.

The overall conclusion seems to be a negative one then. Mental events are perhapscausally relevant to the effects of their neural supervenience bases, but they are notgenuine causes of these. Hence, mental causation is rejected and mental events arenot even redundant causes of physical events as initially inferred above from thescenario illustrated by Fig. 1.

But at this stage an interesting question arises concerning the genuine cause ofM∗e. Clearly, our hypotheses jointly imply that Pc satisfies Contingency, Adequacy,

20The coincidence is important, for the theory does not imply that there cannot be many causes of thesame event. It only says that, within the supervenience hierarchy of the same space-time region, there can,or is typically, only one event that can be considered a cause of an effect in question.

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Fig. 2 The evaluation of Ek�→ (¬Ek�→ ¬E∗)

and Enoughness with respect to M∗e since M∗e supervenes on P ∗e. However, fromthe plausible assumption that Mc displays roughly the same specificity as M∗e, per-haps with recourse to the intuition that the desire to lift the represented glass issufficient to bring about the desire to move one’s arm towards the glass is indepen-dently of how exactly these mental events are realized on the relevant occasion, Mcas well will satisfy Contingency, Adequacy, and Enoughness with respect to M∗e. Inother words, in all worlds sufficiently resembling the actual world, the occurrence ofMc will be enough to secure the occurrence of M∗e independently of the superve-nience bases that Mc happens to have in these worlds. This observation immediatelyimplies that Mc will, and Pc will not, satisfy Requiredness with respect to M∗e.If finally, it is assumed that conditions Contingency, Adequacy, Requiredness, andEnoughness really are jointly sufficient for causation as my investigations into Fal-lacies 1-4 suggested, then Mc must be considered a genuine cause of M∗e, whilst Pccannot be considered a genuine cause of M∗e. In short, if the four conditions are suf-ficient for causation, there are ample reasons to believe in a genuine causal relationbetween Mc and M∗e and mental causation is vindicated at least in this sense.

The overall result is a certain parallelist picture albeit a wholly different one thanthe classical Leibnizian or Spinozian theories. Causal relations run on more than onelevel. However, the different levels are very intimately related through supervenienceconnections and many events are causally relevant for effects on different levels atleast in the sense of Contingency and Adequacy. Ultimately however, only a singleevent usually qualifies as the genuine cause of a given effect in the sense of Required-ness, and Enoughness. That is, causal relevance in the sense of Contingency andAdequacy is not to be confused with causation.

Interventionist Causation and C.A.R.E.

Shapiro and Sober (2007) have recently defend two claims about scenarios as theone depicted by Fig. 1 with the aim to establish a consistent version of non-reductivephysicalism: (i) relative to an interventionist account of causation, as most elaboratelypresented by (Woodward 2003), the argument for the redundancy of Mc relative toP ∗e (cf. section “Counterfactual Fallacies” and KimD 2003) turns out to be invalid;and (ii) interventionism provides the tools to reveal micro effects of macro causes.Shapiro’s and Sober’s approach is interesting for the argument developed in section

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“A Proposal” above as the interventionist theory of causation is often consideredsimply as another version of the counterfactual theory of causation. The idea is thatthe structural equations used in the causal models established on the basis of aninterventionist methodology condense sets of counterfactuals (cf. Hitchcock 2007,501).21

The question then is how Shapiro’s and Sober’s approach relates to the theorydeveloped in the previous sections, or specifically, to the C.A.R.E. conditions forcausation. Do Shapiro and Sober perform a fallacy as well that correponds to one outof Fallacies 1-4? Does their argument contradict or support the above conclusions?To answer these questions is the aim of this section.

Shapiro’s and Sober’s argument originates from Woodward’s main definitions ofa direct cause, a contributing cause, and an independent intervention:

(M) A necessary and sufficient condition for X to be a (type-level) direct cause ofY with respect to a variable set V is that there be a possible intervention on Xthat will change Y or the probability distribution of Y when one holds fixed atsome value all other variables Zi in V. A necessary and sufficient conditionfor X to be a (type-level) contributing cause of Y with respect to variable set Vis that (i) there be a directed path from X to Y such that each link in this pathis a direct causal relationship (...); and that (ii) there be some intervention onX that will change Y when all other variables in V that are not on this path arefixed at some value. (cf. Woodward 2003, 59)

Woodward’s definition of an intervention variable goes as follows:

(IV) I is an intervention variable for X with respect to Y iff

1. I causes X;2. I acts as a switch for all other variables that cause X. That is, certain

values of I are such that when I attains those values, X ceases to dependon the values of other variables that cause X and instead depends only onthe value taken by I;

3. Any directed path from I to Y goes through X. That is, I does not directlycause Y and is not a cause of any causes of Y that are distinct from Xexcept, of course, for those causes of Y, if any, that are built into theI → X → Y connection itself; that is, except for (a) any causes of Ythat are effects of X (i.e., variables that are causally between X and Y)and (b) any causes of Y that are between I and X and have no effect on Yindependently of X;

4. I is (statistically) independent of any variable Z that causes Y and that ison a directed path that does not go through X. (cf. Woodward 2003, 98)

21It should be noted though that there are some important differences between classical Lewisian coun-terfactual theories of causation and Woodwardian ones. For instance, the former are intended to offera reductive account of causation, whereas Woodward makes clear that his account is non-reductive (cf.Woodward 2003, 20-22).

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Shapiro and Sober apply these definitions to scenarious as the one depicted byFig. 1 with its supervenience relation between Pc and Mc and its hypotheticallyassumed causal relation between Pc and P ∗e. They observe that intervening on Mcis impossible without simultaneously intervening on Mc’s supervenience base Pc. IfPc is a (token level) interventionist cause of P ∗e, a change in Mc does result in achange in P ∗e. This they take as evidence that Mc is indeed a cause of P ∗e.22

As Baumgartner (2009, 2010, 2013) has correctly pointed out, Shapiro’s andSober’s conclusion stands only if the variable set V implicitly used for the causalinference is reduced to {I,M,M∗, P ∗}. If the variable set V includes P as well, i.e.if V = {I,M, P,M∗, P ∗}, condition (IV)-4 is violated, as a token intervention Idon Mc is not independent of Pc, whilst Pc causes P ∗e (on a token level) and Pc ison a directed path to P ∗e that does not go through Mc. However, the reduction ofthe variable set is not admissible within Woodward’s framework. In his (2008c, 202),Woodward makes very clear that the notion of an intervention variable defined by(IV) is not relativized to a variable set. Consequently, any intervention on Mc violatescondition (IV)-4 relative to P ∗e.

Subsequently, Woodward (2010, 2011) has responded to Baumgartner’s conclu-sion by pointing out that his definition of an ideal intervention was never intended todemand that an intervention on a variable X should be independent from all variablesnot on the path from X to its effects, if “all” includes X’s supervenience bases as well.

In reply, Baumgartner (2013) has emphasized that this transformation of Wood-ward’s original definition (IV) into a weaker definition (IV*) is actually an adhoc move and therefore methodologically problematic. But even if this new defini-tion (IV*) of an ideal intervention was acceptable, (IV*) leads to the problem thatepiphenomenal and downward-causal structures cannot be distinguished empirically:

“Since the causal effects of supervening mental variables can never be testedindependently of their supervenience bases, this result generalizes: to everycausal structure S1 featuring downward causation there exists a causal struc-ture S2 not featuring downward causation such that S1 and S2 are equivalentwith respect to all possible (IV*)-intervention tests, i.e., such that S1 and S2 areempirically indistinguishable. Hence, all empirical data that result from (IV*)-interventions and that could stem from mental-to-physical causation might justas well stem from a structure that only features physical-to-physical causation.”(Baumgartner 2013, 22)

In light of this equivalence, the altered version of interventionism does notargumentatively resolve the debate between non-reductive physicalism and epiphe-nomenalism. Rather, it simply begs the question against the epiphenomenalist.Hence, if Shapiro and Sober as well as Woodward in their recent papers preferstructures featuring downward causation over epiphenomenalist structures, then thispreference “is entirely non-empirical” (Baumgartner 2013, 24).

22Note that there is a close correspondence between this argument and thoughts presented by (Raatikainen2006, 5–6) and (Weslake 2009, 5–18).

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What are we to make of this debate, especially in light of the theory developedin section “A Proposal”? Several points could be made about the fact that interven-tionism in Woodward’s original version as well as the reformed version may face aproblem very similar to the problem of large causes mentioned above. Woodwardposes no restriction on the formation of variables included into the set V. How-ever, these variables could stand for fused or complex types that are much too largeto be causes of certain effects even if an appropriate intervention should uncover acausal relationship. Such a problem could only be resolved by the introduction of aminimization constraint analogous to Contingency and Adequacy.

However, a more interesting question is whether a set of constraints analo-gous to Requiredness and Enoughness could resolve the empirical equivalence ofepiphenomenalist and downward causal structures that the reformed interventionistframework faces. Interestingly, in two earlier papers (cf. 2008a, 2008b) Woodwardhas insinuated that the interventionist dependencies between Mc and P ∗e, resp. Pcand P ∗e may differ in the sense that the latter may be more stable or better satisfycertain other desiderata, such as “proportionality”, than the former. Moreover, thesedesiderata may also be satisfied by Mc relative to M∗e, and fail to be satisfied by Pcrelative to M∗e. This would suggest that the genuine causal relationships are to befound between Mc and M∗e, resp. Pc and P ∗e, and not between Mc and P ∗e, resp.Pc and M∗e.

The notion of “proportionality” was introduced by (Yablo 1992), and it reflectsclosely the ideas standing behind the C.A.R.E. conditions developed in section “AProposal”. Hence, it seems that, if interventionism wants to avoid empirical equiva-lences for certain objectively non-equivalent structures, there is a general need for itto include into its framework certain further conditions that reflect Requiredness andEnoughness. But once it does include conditions of this kind, it establishes a causalrole for Mc in the scenario depicted by Fig. 1.

The general conclusion of this paper then applies to the interventionist ver-sion of the counterfactual theory of causation as well: In order to be adequate,the counterfactual theory of causation in both its classical and interventionist formmust be supplemented by the C.A.R.E. conditions or analogously formulated con-straints. Once these conditions are included into the counterfactual theory, thereare ample reasons to believe that mental events sometimes satisfy these condi-tions with respect to certain other events and that, hence, mental events sometimesare causes.

Conclusion

Nothing of what has been said in section “A Proposal” makes sense if causation isthought of in terms of, for instance, a transfer of energy from cause to effect. Fur-thermore, the ontology at least tentatively presupposed by the scenario illustrated byFig. 1 and, hence, by the solution presented in section “A Proposal” may be rejectedout of independent reasons. For instance, the claim that sometimes more than a sin-gle event inhabit the same space-time region of the actual world may sound tooextravagant to be tenable.

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Insights of this kind are not of immediate interest to the solution proposed inthis paper, however. All that the investigation shows is that if one adopts the men-tioned ontology including the mentioned assumptions about events and their fusionsand if one thinks of causation in terms of Contingency, Adequacy, Requiredness,and Enoughness, i.e. if one thinks of causation in counterfactual terms, an elegantsolution to the problem of mental causation as illustrated by Fig. 1 becomes avail-able. Perhaps for some metaphysicians the fact that a solution does become availablewill actually count as an argument in favor of such an abundant ontology combinedwith a counterfactual account of causation in the sense of the conditions explicatedabove. However, which ontology and which theory of causation should eventually beembraced for the establishment of a comprehensive worldview is a question beyondthe scope of this paper.

To highlight some of the virtues of the solution, note that the approach based onthe four conditions avoids all of the fallacies presented in section “CounterfactualFallacies”. Counterfactual dependence is not considered sufficient for causation andnot all events coinciding with a genuine cause are immediately declared genuinecauses of the relevant effect. Secondly, note that the solution supplements a numberof recent proposals for pluralist ontologies with parallelist leanings such as Gibbons(2006), Huttemann and Papineau (2005), Craver (2007) and others. At the same time,the theory of section “A Proposal” has the advantage of being more technically pre-cise than some of these approaches. Thirdly, note that the solution of section “AProposal” does not violate the famous “completeness of the physical” hypothesis,at least if “physics” is understood as “microphysical” instead of “broadly physical”(cf. Sturgeon 1998). The idea is, of course, that every causal level satisfies a certaincompleteness hypothesis whilst there is no genuine interlevel causation.

As a final point in favor of the solution of section “A Proposal”, it should be men-tioned that the approach effectively blocks certain worries about a possible drainageof causal powers even if it should turn out that the world has in fact no fundamentallevel as Block (2003) and Schaffer (2003) have speculated. If causation is understoodin terms of Contingency, Adequacy, Requiredness, and Enoughness genuine causalrelations run on many levels and remain in place no matter how “deeply constituted”the world turns out to be eventually.

An great amount of detail work still remains to be done, however. In particular, itremains to be seen how the account fares in an analysis of actual folk-psychologicalexplanations stating mental events as causes as well as in an analysis of actual expla-nations of cognitive science citing mental events as causes of behavioral effects.Furthermore, if an ontology of parallel causal relations and coincident events is actu-ally accepted, difficult questions remain concerning the behaviour of levels in thetotal history of a world (cf. Harbecke 2008, sec. 4.4). Whether or not the solutionof section “A Proposal” is eventually considered acceptable will crucially depend onthe outcome of these further “inhouse” discussions as well.

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