Journal of Philosophy, Inc. Causation Author(s): David Lewis Reviewed work(s): Source: The Journal of Philosophy, Vol. 70, No. 17, Seventieth Annual Meeting of the American Philosophical Association Eastern Division (Oct. 11, 1973), pp. 556-567 Published by: Journal of Philosophy, Inc. Stable URL: http://www.jstor.org/stable/2025310 . Accessed: 23/01/2012 16:14 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Journal of Philosophy, Inc. is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Philosophy. http://www.jstor.org 556 THE JOURNAL OF PHILOSOPHY CAUSATION * Hr UME definedcausation twice over. He wrote "we may de- finea cause to be an objectfollowed by another, and whereall theobjects, similar to thefirst, are followedby objects similar to thesecond. Or, in otherwords, where, if thefirstobject had notbeen, thesecond never had existed."' Descendants of Hume's firstdefinition still dominate the philo- sophy of causation: a causal succession is supposed to be a succes- sion that instantiates a regularity.To be sure, there have been improvements.Nowadays we tryto distinguishthe regularitiesthat count-the "causal laws"-from mereaccidental regularitiesof suc- cession. We subsume causes and effectsunder regularitiesby means of descriptionsthey satisfy, not by over-allsimilarity. And we allow a cause to be only one indispensablepart, not the whole,of the total situationthat is followedby the effectin accordance with a law. In present-dayregularity analyses, a cause is defined(roughly) as any memberof any minimalset of actual conditionsthat are jointlysuf- ficient,given the laws, forthe existenceof the effect. More precisely,let C be theproposition that c exists (or occurs)and let E be the propositionthat e exists.Then c causes e, accordingto a typical regularityanalysis,2 iff (1) C and E are true; and (2) for some nonemptyset ? of truelaw-propositions and some set 3Fof true propositionsof particular fact, S and 5Yjointly imply CD E, al- though ? and 5Fjointly do not implyE and 9f alone does not imply CD E.3 Much needs doing, and much has been done, to turndefinitions like thisone intodefensible analyses. Many problemshave been over- come. Othersremain: in particular,regularity analyses tend to con- fuse causation itselfwith various othercausal relations.If c belongs to a minimalset of conditionsjointly sufficient for e, given the laws, * To be presentedin an APA symposiumon Causation,December 28, 1973;com- mentatorswill be BernardBerofsky and JaegwonKim; see this JOURNAL, this issue,pp. 568-569and 570-572,respectively. I thankthe American Council of LearnedSocieties, Princeton University, and the NationalScience Foundation for research support. 1An Enquiryconcerning Human Understanding,Section VII. 2 Not onethat has beenproposed by any actual author in just thisform, so faras I know. 3 I identifya proposition,as is becomingusual, with the set of possibleworlds whereit is true.It is nota linguisticentity. Truth-functional operations on prop- ositionsare theappropriate Boolean operations on setsof worlds; logical relations amongpropositions are relationsof inclusion, overlap, etc. amongsets. A sentence of a languageexpresses a propositioniff the sentence and the propositionare true at exactlythe same worlds.No ordinarylanguage will providesentences to ex- pressall propositions;there will not be enoughsentences to go around. CAUSATION 557 then c may well be a genuine cause of e. But c mightrather be an effectof e: one whichcould not,given the laws and some of the actual circumstances,have occurredotherwise than by being caused by e. Or c mightbe an epiphenomenonof the causal historyof e: a moreor less inefficaciouseffect of some genuinecause of e. Or c mightbe a preemptedpotential cause of e: somethingthat did not cause e, but that would have done so in theabsence ofwhatever really did cause e. It remainsto be seen whetherany regularityanalysis can succeed in distinguishinggenuine causes fromeffects, epiphenomena, and preemptedpotential causes-and whetherit can succeed without fallingvictim to worse problems,without piling on the epicycles, and withoutdeparting from the fundamentalidea that causation is instantiationof regularities.I have no proofthat regularityanalyses are beyondrepair, nor any space to reviewthe repairsthat have been tried.Suffice it to say that the prospectslook dark. I thinkit is time to give up and trysomething else. A promisingalternative is not far to seek. Hume's "other words" -that ifthe cause had not been, the effectnever had existed-are no mere restatementof his firstdefinition. They propose somethingal- togetherdifferent: a counterfactualanalysis of causation. The proposal has not been well received.True, we do know that causation has somethingor other to do with counterfactuals.We thinkof a cause as somethingthat makes a difference,and the dif- ferenceit makes must be a differencefrom what would have hap- pened withoutit. Had it been absent, its effects-some of them,at least, and usually all-would have been absent as well. Yet it is one thingto mentionthese platitudesnow and again, and anotherthing to rest an analysis on them.That has not seemed worthwhile.4 We have learned all too well that counterfactualsare ill understood, whereforeit did not seem that much understandingcould be gained by using them to analyze causation or anythingelse. Pending a betterunderstanding of counterfactuals,moreover, we had no way to fightseeming counterexamples to a counterfactualanalysis. But counterfactualsneed not remain ill understood,I claim, un- less we cling to false preconceptionsabout what it would be like to understandthem. Must an adequate understandingmake no refer- ence to unactualizedpossibilities? Must it assignsharply determinate truthconditions? Must it connectcounterfactuals rigidly to covering laws? Then none will be forthcoming.So much the worse forthose standardsof adequacy. Why not take counterfactualsat face value: 40ne exception:Aardon Lyon, "Causality," British Journal for Philosophy of Science,XVIII, 1 (May 1967): 1-20. 558 THE JOURNAL OF PHILOSOPHY as statementsabout possible alternativesto the actual situation, somewhatvaguely specified, in whichthe actual laws may or may not remain intact? There are now several such treatmentsof counter- factuals, differingonly in details.5 If they are right, then sound foundationshave been laid foranalyses that use counterfactuals. In this paper, I shall state a counterfactualanalysis, not verydif- ferentfrom Hume's second definition,of some sorts of causation. Then I shall tryto showhow thisanalysis works to distinguishgenu- ine causes fromeffects, epiphenomena, and preempted potential causes. My discussionwill be incompletein at least fourways. Explicit preliminarysettings-aside may preventconfusion. 1. I shall confinemyself to causation among events,in the every- day sense of the word: flashes, battles, conversations,impacts, strolls,deaths, touchdowns, falls, kisses, and thelike. Not thatevents are the only thingsthat can cause or be caused; but I have no full list of the others,and no good umbrella-termto cover themall. 2. My analysis is meant to apply to causation in particularcases. It is not an analysis of causal generalizations.Presumably those are quantifiedstatements involving causation among particularevents (or non-events),but it turnsout not to be easy to matchup thecausal generalizationsof natural language with the available quantified forms.A sentence of the form"c-events cause E-events," for in- stance, can mean any of (a) For some c in c and some e in E, C causes e. (b) For everye in E, thereis some c in c such that c causes e. (c) For every c in c, there is some e in E such that c causes e. not to mention furtherambiguities. Worse still, 'Only c-events cause E-events'ought to mean (d) For everyc, if thereis some e in E such that c causes e, then C is in C. if 'only' has its usual meaning.But no; it unambiguouslymeans (b) instead! These problems are not about causation, but about our idioms of quantification. 3. We sometimessingle out one among all the causes of some event and call it "the" cause, as ifthere were no others.Or we single out a few as the "causes,'' calling the rest mere "causal factors"or "causal conditions." Or we speak of the "decisive" or "real" or "principal" cause. We may select the abnormal or extraordinary I See, forinstance, Robert Stalnaker, "A Theoryof Conditionals,"in Nicholas Rescher,ed., Studies in LogicalTheory (Oxford: Blackwell, 1968); and myCounter- factuals(Oxford: Blackwell, 1973). CAUSATION 559 causes, or thoseunder human control,or thosewe deem good or bad, or just those we want to talk about. I have nothingto say about these principlesof invidious discrimination.'I am concernedwith the priorquestion of what it is to be one of the causes (unselectively speaking). My analysis is meant to capture a broad and nondis- criminatoryconcept of causation. 4. I shall be content,for now, if I can give an analysisof causation that works properlyunder determinism.By determinismI do not mean any thesis of universalcausation, or universalpredictability-