Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 hand, they pursue an otherthe on explanation; to related is aspect disease—this of mechanisms identifying be unnecessaryandmisleading.Forinstance,Lipton andOdegaard(2005)claim, toclaimed even is ‘risk’—or or ‘determinant’, ‘factor’, as such terms causal obviously where causal terminology is frequently disguised—e.g., ‘cause’ is often replaced with less sis ortreatmentonthebasisofcausalknowledge—thisaspectisrelatedtoinference. the one hand, the health sciences pursue a pursue sciences health the hand, one the Onobjective. twofold a has causes for search This treatments. effective for and disease It is quite uncontroversial that the health sciences look for causes, namely for causes of 1. Introduction ‘Smoking causes lung cancer’, does not convey more information than statement (2)statement than information more convey not does cancer’, lung (1)causes ‘Smoking statement in used as terminology, causal explicit that show to aims paper Their aspects. We argue that the the health sciences require a theory of causality that unifies its mechanistic and probabilistic cause in these sciences—pluralism about causality will not do either. Instead, we maintain, not do justice to the causal claims of these sciences. Yet there seems to be a single relation of solely ical mechanisms, and of probabilistic dependencies. Consequently, an analysis of causality DOI: 10.1080/02698590701498084 ISSN 0269–8595 (print)/ISSN1469–9281(online) ©2007Inter-UniversityFoundation United 7NF, CT2 Canterbury Kent, of University SECL, Kingdom. E-mail:[email protected], [email protected] Philosophy, of Department to: Correspondence Federica RussoandJonWilliamson areattheDepartmentofPhilosophy,UniversityKent. We argue that the health sciences make causal claims on the basis of evidence Taylor andFrancisLtdCISP_A_249681.sgm10.1080/02698590701498084InternationalStudiesinthePhilosophyofScience0269-8595(print)/1469-9281(online)OriginalArticle2007Taylor000000July 2007DrFederica RussoandJonWilliamson [email protected] &Francis212 Sciences Interpreting CausalityintheHealth Vol. 21,No.2,July2007,pp.157–170 International StudiesinthePhilosophyofScience However, this causal perspective is not always made explicit in the scientific literature, the research findings at hand, one doesn’t have to say that to predict and intervene at the public health level, to tell the best story possible about researchepidemiological use to able be to important is it although that is point Our Odegaard 2005,7) and(Lipton relationship. a such claim definitively cannot one fact, In outcome. an in terms of physical mechanisms or action-oriented epistemic theory of causality provides the required unification.
goal solely , informing policies and guiding early diagno- cognitiv in terms of probabilistic relationships, does e goal , detecting causal factors andfactors causal detecting , X causes Y to achieve such both of phys- Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 not because health scientists use statistics and mechanisms to support a single causal claim, either,do won’t account pluralistic a that claiming in further goes 6 Section causality. ofepistemology dual-faceted the explain cannot they that argue we cause; of concept whichto traditional monistic accounts extent (either mechanistic or the probabilistic) provide a successfulevaluates 5 Section effect. an of occurrence the explain to ships relation-causal allow mechanisms and effect, the to difference a makes cause the that ical knowledge, and, on the other, statistics and probabilities. Statistics are used to showinfer causal relations from mixed evidence: on the one hand, mechanisms and theoret- follow fromthefactthatthereareatleasttwokindsofevidenceforcausalassertions. listic one. We will argue that the claim that there are at least two types of cause does not there are different coexisting types of cause, e.g., a mechanistic relation and a probabi- they neglect and fail to account for the others. However, pluralistic accounts hold that of mechanisms or solely in terms of probabilistic relations, focusing only on one aspect attempt to analyse causality solely in terms of one type of evidence, e.g., solely in terms accountsMonistic relationships. causal putative support to used evidence of types the withitself relation causal the confuse to not ought one relations, probabilistic of and causal relations are inferred from mixed evidence, including knowledge of mechanismsalthoughthat argue shall We attention. philosophical close deserves and importance genic factors,whichareneithernecessarynorsufficientcausesofcancer. a definition of cause in terms of necessity does not suit the case of exposure to carcino- probabilisticbutAIDS, of cause necessary a is infection HIV instance, For operate. causes which in cause, sufficient-component cause, causation, and counterfactual. None of these necessary can alone account for all the possible ways production, ofmeanings ‘cause’: different five isolate (2001) Weed and Parascandola consensus. firm a Weed 2001). They isolate several, none of which seems to be fully satisfactory or attract concept of cause as it is used in scientific practice (Lagiou et al. 2005; Parascandola and advertising) tobacco restricting by requires statement(1)tobetrueaswell. (e.g., intervene To cause). common a of effects arecancer and smoking if (say false is (1) statement while true be could (2) statement in information standpoint, health public statement (2) has to or be made explicit. It is worth epidemiological noting why this line of reasoning an fails: from useful be to cancer would be 10 times greater than a non-smoker’, and, moreover, for statement (1) ‘If you smoked two packs a day for day a packs two smoked you ‘If 158 h cgiie n ato-retd ol giig eerh n h hat sciences health the in research guiding demand that phenomena be goals action-oriented and cognitive The 2. TwoTypesofEvidence probabilistic accounts. andmechanistic the transcending account, unified a as causality of theory epistemic The paper is organised as follows. Sections 2, 3, and 4 argue that the health scienceshealth the that argue 4 and 3, 2, Sections follows. as organised is paper The crucialof is sciences health in interpreted be to is causality how of question This a extrapolate to try articles review recent language, causal on attack this Despite o support to F. RussoandJ.Williamson tw o different systematised
type o cua cam Fnly scin peet the presents 7 section Finally, claim. causal of s X amount of years, your chance of getting lunggetting of chance your years, of amount and explained : these sciences need to provide Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 dependencies. WitnessforinstanceHalesandBarker(2001): mechanism.ofaccount particular any to commit not do we mechanisms, need we that saying in butlaw, Bungewith are we general Although provided. is it about bringing more mechanism the when only a from it deducing by explained not is fact a explanation: of modelcovering-law the against argues he and tick’, question in system the makes that mechanism(s)the exhibit to is fact a explain ‘to that claims 182) (2004, Bunge is. tion explana-good a what of account an give to pretend not do sense—we broad a in of mined byprobabilisticevidencealone—seesection4. underdeter-are that models causal between differentiate to used be can mechanisms plausible mechanism from mechanism plausible causes mechanism or theoretical connection is required to warrant the more general claim ‘ claim. In the remainder of this section and in sections 3 and 4 we shall describe somedescribe shall we 4 and 3 singlesections in and section a this of remainder the but In claim. claims causal different support not do evidence of types two these that argueshall we 6 section In diabetes. cause phenotypes given the whether to as ment assess-the in underlyingparticipate both established; an be can by claim causal the for before mechanism accounted be to needs evidence probabilistic that is idea The aa a wrat cua cam ‘ claim causal a warrant can data mechanismsallow us to words, other In repeatable. sufficiently not relationship—and ‘fragile’ is correlation the because be particular to a specific sample may population or a specific set of circumstances—i.e., it is a that found, were mechanism no If populations. ofvariety a over stable relation causal the making individuals, of range a in occur to relationship. If we can single out a plausible mechanism, then that mechanism is likely are alsomeanttobeexplanatory. relationshipscausal sciences health the in and dependencies, the explain mechanisms becauserequired is aspect mechanistic the But dependence. probabilistic appropriate somebe to needs there i.e., effects, its to difference a make to needs cause a bepossible, to inference of modes these for intervention; and diagnosis, prediction, for used and mechanisms.probabilitieselements: complementary two by constituted is Evidence policies. and coherent and sensible stories about causation of disease and about effective treatments To establish causal claims, scientists need the mutual support of mechanisms andmechanisms of support mutual the need scientists claims, causal establish To conceivedhere is Explanation disease. of explanations provide sciences health The Moreover, the existence of a mechanism provides evidence of the stability of a causal areclaims causal sciences, health the in because, crucial is aspect probabilistic The obnd ih fet o oeiy aen ad hscl nciiy ae h most the are inactivity, physical and ageing important factorsindeterminingtype2diabetes.(Hales andBarker2001,5) obesity, of effects with Thesecombined metabolism. glucose-insulin in which,resistance insulin and secretion insulin for capacity reduced include changes changes permanent produces which life, 2type of diabetes development and the subsequent metabolic syndrome result the from the effects and of poor growth nutrition in earlyinfant and associationsfetal epidemiological poor between the that proposes hypothesis phenotype thrifty The E . ovrey mcaim as ips ngtv cntans i tee s no is there if constraints: negative impose also mechanisms Conversely, ’. generalis e a causal relation: while an appropriate dependence in the sample C to E , then any correlation is likely to be spurious. Thusspurious. be to likely is correlation any then , C International StudiesinthePhilosophyofScience causes E n h sml pplto’ a plausible a population’, sample the in 159 C Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 Hill putforwardthefollowingninecriteria: beprobabilistic should and mechanistic aspects are already present in that these criteria for causation. issues nine discussed Medicine, addressed when deciding of whether an observed association is causal Society (see Hill 1965). The Royal the of Medicine evidence. ofkinds two require sciences health the in claims causal that view the for precedents 160 analogous tothatofKoch’spostulatesformicrobiology. causalrelations. In occupational and environmental evaluating risk assessment, these criteria play a rolefor rationale a as practice Hill’sscientific in certainty. used with widely causality still are ensure criteria not do they causality, assessing in guide a as diseases don’t have casemerely one many cause. in Needless to that besay, while indicates these to criteria models were multi-causal intended seems of criterion development the sixth as The problematic considerations. probabilistic involve 8 and 7, 3, 1, In 1965 Bradford Hill, in his Presidential Address to the Section of Occupationalof Section the to Address Presidential his in Hill, Bradford 1965 In Kundi, commentingonHill’scriteria,says Roughly, criteria 2, 4, 5, 8, and 9 involve mechanistic considerations, while criteriawhile considerations, mechanistic involve 9 and 8, 5, 4, 2, criteria Roughly, to the disease. However, they were not intended to dismiss a factor as potentiallyas factor causing thedisease.(Kundi 2006,970)a dismiss to intended not were they However, disease. the to specific factor, this would increase our confidence in this factor being acausally for relatedmet are they case the in that, such established were criteria Hill Bradford The :Aaoy Smtms cmol acpe peoeo i oe ra a be can area one in phenomenon accepted commonly a Sometimes Analogy. 9: willexperiments on based is that research related Any Evidence. Experimental 8: thebetween relationship direct a be should There Relationship. Response Dose 7: Incause. one only has effect the situation, ideal the In causes. the in Specificity 6: Coherence. A cause-and-effect interpretation for an association is clearest when it5: Theoretical Plausibility. It is easier to accept an association as causal when there is4: Consistency. Multiple observations, of an association, with different people under3: Temporality.Itislogicallynecessaryforacausetoprecedeaneffectintime. 2: independentthe between relationship the stronger The Association. of Strength 1: F. RussoandJ.Williamson applied toanotherarea.(Frumkin2006,1) make acausalinferencemoreplausible. able (i.e.,thedependentvariable). risk factor (i.e., the independent variable) and people’s status on the disease vari- factoradds credibilitytoacausalclaim.primary one by predicted best is outcome an that showing words, other association mustbecoherentwithotherknowledge. there are no plausible competing theories or rival hypotheses. In other words, the whenand study under variables the about known is what with conflict not does a rationalandtheoreticalbasisforsuchconclusion. credibility ofafinding. different circumstances and with different measurement instruments increase the to anextraneousvariable. variable and the dependent variable, the less likely it is that the relationship is due Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 In thenexttwosections weshalldiscussthesetwotypesofevidencein turn. n poaiitc vdne r rqie t sbtnit cua cam. hs for Thus, claims. causal substantiate to instance, Daltonetal.(2002)sumuptheirstudy asfollows: required are evidence probabilistic and onrelative risk.or population a in frequency cancer on i.e., evidence, probabilistic on and nism in of stated mecha-plausible a of cause presence are the on depends possible causality evaluations of Assessment (2006). a IARC their is guiding factor principles a and that procedures claim Criteria, the cancer. for and evidence studies of published weight review the scientists evaluate IARC research. cancer for agencies major theof one (IARC), Cancer on Research for Agency International the by recognized is criteria canbeappliedtotheclassiccaseofsmokingandlungcancer: Hill’show see let’s illustrate, To aspects. probabilistic and mechanistic both consider Thus the criteria are not necessary for causation, but they are a valuable tool since they Consequently in the health sciences it is now a commonplace that both mechanistic The crucial and equal importance of probabilistic and mechanistic considerationsmechanistic and probabilistic of importance equal and crucial The 9) ilgcl ehns ad qioa fnig o ds-epne relationships dose-response et al.2002,1) of findings (Daltonfactors. risk established are factors psychological equivocal that conclusion underlyinga prevent unresolved and the mechanism results, the biological of events, inconsistency life the weak generally major found, The ... between associations cancer. for association risk the an and factors for personality and evidence depression the reviewed have We 8) 6) 4) 7) 5) 3) 2) 1) 2006, 2) (Frumkinhumans. to this apply to scientists for jump great a not was therefore, Analogy were presentintobaccotar. carcinogensthat clear was it Hence, time. over tissue ear the in cancer produce Experimental EvidenceExperimental amount smokedandtheincidenceoflungcancer. Dose-response relationship smoking. causes the in Specificity the currentknowledgeaboutbiologyandhistoryofdisease. Coherence which, overtime,resultsincancerthecellswasahighlyplausibleexplanation. plausibilityTheoretical people (e.g.,malesandfemales). ofkinds different for appeared also relationship The result. same the produced Consistency cancer. Temporality likely thannonsmokerstogetlungcancer). than for nonsmokers (e.g., one study estimated that smokers are about 35% more associationof Strength Soig nue i lbrtr rt soe a asl eainhp It, relationship. causal a showed rats laboratory in induced Smoking . . The conclusion (that smoking causes lung cancer) ‘made sense’ givensense’ ‘made cancer) lung causes smoking (that conclusion The . Dfeet ehd (.. popcie n rtopcie studies) retrospective and prospective (e.g., methods Different . . Smoking in the vast majority of cases preceded the onset of lungof onset the preceded cases of majority vast the in Smoking . . The lung cancer rate for smokers was quite a bit higherbit a quite was smokers for rate cancer lung The . Booia ter o soig asn tsu damage tissue causing smoking of theory Biological . Ln cne i bs peitd rm h icdne of incidence the from predicted best is cancer Lung . . Tar painted on laboratory rabbits’ ears was shown toshown was ears rabbits’ laboratory on painted Tar . . Data showed a positive, linear relationship between the International StudiesinthePhilosophyofScience 161 Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 cancer involves a physiological mechanism, but it is also a chain of theoretical explana- lungand smoking of case the in invoked mechanism The mechanism. biomedical a of examplesimplified a is This division. cell particular, in cells, the alter agents chemical thesewhen develops then Cancer mucus. the in trapped therefore are smoke cigarette inagents Cancer-producing effectively. itself cleanse cannot lung the thus inhalation; smokeby destroyed are particles, inhaled remove to rhythmically beat which lungs, know how the physiological mechanism operates in the lungs. The hair-like cilia in the nowWe variables. two the between correlation the of evidence as well as mechanism, physiologicalplausible a of evidence required hypotheses two the between decision Acancer. lung causes smoking that claim the from claim common-causal this guish distin-own its on not did evidence Probabilistic 1958). 1957, (Fisher cancer and ing Sir Ronald Fisher, who argued that a genetic factor might be a common cause of smok- explanations. theoreticalof chains of composed physicalare they that others conserved dependencies, counterfactual transmitting orprobabilistic of processes chains of composed are mechanisms be that claim others quantities; to mechanisms view here—some at the cellular level, etc. Exactly what constitutes such mechanisms will not concern us alterationssignals, electric reactions, chemical involve may mechanism biomedical A 4. MechanisticEvidence source ofwater. theon dependent bywas cholera of incidence the that water 1854, in found, he until accepted drinking contaminates that organism living proximity to sewage. Although a he had hit upon the mechanism, by the causal claim wasn’t caused was infection cholerathat suspected Snow 1849 In 1855). (Snow this of example clear a is thecholera for oftransmission the warrant of discovery the enough of case be The place. first not the in claim may mechanistic there dependence some of evidence without course,Of it. to difference no or little makes actually it, to connected mechanistically andeffect the to prior although cause, purported the that case the be may it as claim, discover bothbiologicalandsocialcomponentsofdiseases. toorder in sciences, health the in studies research all almost of feature key a thus are est, and the reliability of results also depends on the chosen significance level. Statistics inter-of parameters of stability the for tests require models Structural relation. acausal of presence the for evidence good be can correlations strong causation, prove not doescorrelation known, well is as Although, list. Hill’s in criteria coherence and tency results (positive, negative, or absence of dependency). These correspond to the consis- enough—several not is study single A studies of the same putative causal relation need to be performed and to give coherent studies. similar of range a in dependencies observedof consists mainly sciences health the in required evidence probabilistic The 3. ProbabilisticEvidence 162 The causal link between smoking and lung cancer was hotly disputed by the eminent causala warrant not can own its on evidence mechanistic that uncontroversial is It F. RussoandJ.Williamson Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 in n peprl ee ws cetd ny fe te em hoy f ies was disease of theory germ the after the and only developed accepted was fever puerperal and tion contamina-cadaverical about claim Semmelweis’ hypothesis, this corroborating ered gath-statistics extensive the subsequentlyof spite In they them. examining when patients contamination; their infected of source possible any eliminate to enough well handstheir wash to failed students medical and doctors autopsies, out carried having afterfact, In particles. ‘cadaverical’ of contamination by caused was fever puerperal thatidea the with up came Semmelweis hypotheses, cause.several considered the having find After to wanted hospital, the at physician wereassistant which fever an of Semmelweis, rate, puerperal Ignaz death higher to significantly a due showed clinics deaths two and the of births One collected. on statistics and clinics, two into after fever dividedwas Hospital Maternity puerperal Vienna the 1833 In of serious. extremely was childbirth risk the Austria, 19th-century in theoretical instance, or For mechanistic knowledge. by backed until rejected been have statistics of basis the be usedtoruleoutFisher’shypothesis. canmechanism this Moreover, cancer. and smoking between correlation the of tions causal claim. aaccept to not or whether deciding when stake at mechanistic—are and probabilistic icse (e, o isac, ile 20; hgr 19) o ae pit about a point is a instead, make to 1998) Thagard point,Our sciences. biomedical the in formulation hypothesis or paradigm of 2005; change Gillies instance, for (see, discussed cetd ni bce u b mcaitc vdne ie, ni te em hoy hadand theory cases—Semmelweis germ historical both the Also, until developed. been i.e., not evidence, was mechanistic claim by this up that backed is until matters accepted what but alone, evidence statistical of basis the on fever he puerperal whether and clear contamination not cadaveric is between relation it the Semmelweis, hypothesised of case the In community. medical the by discovery of discovery theof or fever puerperal of case the in (as hypotheses causal (controversial) with up secreting ammonia). nisti also but antibiotics) to resulting recoveries between covariation and ulcer and h cua rlto ws ny cetd fe frhr vdne a gtee; this gathered; was evidence further after accepted only was evidence was relation causal 115),the 1998, Thagard in quoted Marshall, and Warren (see evidence probabilistic of basisthe on hypothesised first was relation causal the Although walls. stomach the in thepyloriH. theory, available thatknow to now We survive. to bacterium a according for environment an acidic too is because, stomach hypothesis this accepting in sceptical epnil fr ati ucr Atog tee a sgiiat rbblsi evidence probabilistic to significant pointing was there Although ulcer. gastric for responsible viable mechanism(seeGillies2005;Kundi2006). The history of medicine presents many cases in which causal claims made solely onsolely made claims causal which in cases many presents medicine of history The It is worth pointing out that we are not concerned, here, with how scientists camescientists how with here, concerned, not are we that out pointing worth is It o ie nte eape qie eety eerhr dsoee te bacterium the discovered researchers recently quite example, another give To (eerhr fud ht hs atru cn uvv i ai evrnet by environments acid in survive can bacterium this that found (researchers c produces ammonia, which neutralizes stomach acid and allows it to surviveto it allows and acid stomach neutralizes which ammonia, produces eioatr pyloriHelicobacter H. pyloriH. theoretical probabilisti Vibri ) but rather with how those hypotheses have become acceptedbecome have hypotheses those how with rather but ) u nt n itrcl n: w different two one: historical an not but c (in particular, covariation between presence of helicobacterof presence between covariation particular, (in c o co holera s cue f les te eia cmuiy was community medical the ulcers, of cause a as e had been isolated by Robert Koch, establishing aestablishing Koch, Robert by isolated been had e International StudiesinthePhilosophyofScience H. pyloriH. type s of —have been—have
evidence mecha- 163 — Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 Here we will be concerned with the question of whether of question the with concerned be will we Here fitdomains?all in cause relations causal for of account notion single notions a does or different contexts different Do adopted. be to ought causality of view monistic a orpluralistic a whether of question the to turned recently has causality on debate The 5. AgainstCausalMonism 164 propose aprobabilistic understanding ofcause: notion is perhaps probabilisticthe leading A contender. sciences. Witness, for health instance, Lagiou the et fits al. (2005) best whothat cause of definition the out single to mentioned in section 1, a number of review articles in epidemiology have recently tried required evenwhenappropriateprobabilisticassociations arewellestablished. the other, aremechanisms the that fact the on for account can’t and, theory probabilistic the of uncontroversial, proponent is mechanism underlying the where even analysiscausal in methods and data probabilistic of use widespread the for account can’ttheory mechanistic the of proponent the hand, one the On claim. causal single aprobabilistic—for and evidence—mechanistic of types two for need the for account adequatelycan approach difference-making the nor mechanistic the Neither mology. due toacommoncause. advanced: ( pluralistic oramonisticaccount. neato te ae oie ad hne prit fe te on o intersection. of point the are after interactions persist and Processes changes and modifed are they interaction thisin forks, interactive in another one with intersect processes effects; the and causes thebetween link the supply they because key the are processes Physical momentum). process and interaction and appeals to laws of nature (e.g., conservation of energy and Salmon-Dowe process theory (Dowe 2000; Salmon 1998). This theory uses concepts of terms of physical processes. Perhaps the primary example of this type of account is the hi efcs Cue ae fe asmd o rcd ter fet i tm, n other and time, in of dependency effects that ensure to imposed their be may conditions precede to assumed often are Causes effects. their of a probability-changing requirement: significant differences among them, a core of agreement Despitecan be found in the basic decades. idealast the in authors different by ways of variety a in developed been 1986 (Lewis causality of ; Price 1991; Suppes 1970). Probabilistic theories of causality, for instance, have theories agency and counterfactual probabilistic, include as involving the notion of change, rather than mechanism. Examples of such accounts processes areatstake.Thus,theprocesstheoryqualifiesasamonisticapproach.socio-politicalcomplex where sciences, social the in physics—e.g., outside domains ineven causality explicate will interactions and processes physical that states clearly characterised in terms of relationships among probability values alone. Salmon (1990) h sac fr h ntr o cuaiy s use nt ny y hlspes As philosophers. by only not pursued is causality of nature the for search The episte-causal of aspect dual the handle to fail account of types both Unfortunately, In the philosophical literature two types of monistic account have traditionally been The mechanistic approach holds that causal connections are to be understood inunderstood be to are connections causal that holds approach mechanistic The In contrast, proponents of difference-making accounts see the concept of causationof concept the see accounts difference-making of proponents contrast, In F. RussoandJ.Williamson i ) amechanisticapproach;and( physical ceteris paribus tutrs ad hi poete cno be cannot properties their and structures, ii ) adifference-makingapproach. , causes change the probability of th E e and health C is not spurious orspurious not is
science s require arequire s Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 different types of causal claim, causal of types different have more than one concept of cause, while type ofevidence.Forinstance, inHwangetal.(2003),weread, onethan more admits that relation a albeit relation, one isolate to word one use but things,two between equivocate to word one use not do They sense. single a in ‘cause’ of pluralismare,weargue,implausible. two causal relations ambiguously picked out by a single concept of cause. Both varieties ontological pluralist without being a conceptual pluralist by maintaining that there are pluralism normally presupposes ontological pluralism. However, it is possible to be anconceptualrelation—i.e., causal different a out picks cause of concept each that hold normallypluralists Conceptual world. the in relation causal of type one than more is of causeisusedinthehealthsciences,pluralismfalse. scientists use two types of evidence of types two use scientists healthspecifically, More sciences. health the in used is cause of notion single a only argue,will we contrary, the On succeed. will accounts pluralistic that hope might one If monistic theories fail to provide an adequate account of cause in the health sciences, 6. AgainstCausalPluralism an given rate, birth increased an of cause a appropriate dependency. considered be the to in increase storks an of allow number would move—it dangerous a is evidence mechanistic for evidence. Thus it makes the need for mechanistic evidence a mystery. Denying the needprobabilisticthis up backing mechanism plausible any be there that require itnot does requirement; difference-making a to appeals only cause of definition This above. While studies don’t often adopt explicit causal vocabulary, where they do they usethey do they where vocabulary, causal explicit adopt often don’t studies While Note that causal pluralism takes two forms. hs rbblsi acut ufr fo te pseooia polm highlighted problem epistemological the from suffers account probabilistic This In thesamevein,Kundi(2006)claims, of thedisease.(Kundi2006,7) probabilitythe increase that conditions exclusive mutually of set a is cause disease a populations of subjects that are sufficiently similar for the problem under study, then In this pragmatic sense disease cause can be defined as follows: Consider two or more al. et (Lagiou a of period). passage induction the or after latency, 2005, 565) disease, (incubation, the period of time occurrence certain of frequency by the followed of are in factor, intensity other changes or any frequency in the alterations in concomitant alterations without when factor, this disease certain a of cause a factoris (for a etc.): findings psychoses, clinical disorders, occupa- tissue or connective and tumors, laboratory malignant infectious example, specified many by example, documented on or (for defined diseases) exposure whether tional particular diseases, a all of to basis applies cause the a of definition following The related deaths in the United States and in many developed countries. … Cigarette… countries. developed cancermany in of and States causes United leading the in the deaths related are bronchus and lung the in neoplasms Malignant C- causes International StudiesinthePhilosophyofScience for a 1 - single causal claimcausal single E and ontological Conceptual C- causes pluralism is the view that there 2 pluralism is the view that we - E , ‘, . Because only Because . C causes E ’, not for twofor not ’, one notion 165 Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 lismcaitc n poaiitcad ocue ta tee r to ye of types two are there that concludes probabilistic—and and claims—mechanistic Thiscausalfor evidence of types two accounts. are there that notes who pluralist monistic the affects problem of difficulties the inherits it that namely, pluralism, besets not account for the homogeneity of causal language. But there is a second problem that We see then that pluralism about the nature of causality faces a crucial problem—it can the healthsciencesisalsosupportedbycausallanguageofItaliano(2006): That patients. cancer breast of 10% incause of notion single a in up bound closely are difference-making and mechanism to difference a making with and mechanism cancer susceptibility genes” (BRCA)’ the word ‘caused’ is associated both with a ovariangeneticand “breast the of one in mutation pathogenic a by caused i.e., “hereditary”, forarecancers breast looking of 10% ‘About clearly says 680) (2006, are Kuhl when Likewise, scientists potencies’). the humans’); and rats mechanisms (hence the physiological model) and for difference-making, too (‘relative in effect of level same Here causal language is used (‘the same concentration in the target tissue may cause the of causebuttwotypesevidence.Similarly,MaruyamaandAoki(2006)say, to not dependencies, varietiestwo and not are There probabilistic. one and mechanistic mechanisms one relations, different both with associated is which relation one The words ‘causes’ and ‘causally’ in this passage are used in the same sense—to refer to 166 (Italiano 2006,161) was chemotherapy, on.go must EGFR against treatment to to response of markers for search the resistance Clearly, reversed and benefit.clinical with correlate not did EGFR patients, of expression However, news. exciting in response a iscaused agents factor-a growth these transforming EGFRagainst antibodies monoclonal and that finding of the Thus, EGFR. EGF into (TGF-alpha) of promising and binding most the agents blocks the single which cetuximab, as and activity chemotherapy clinical with demonstrated combination have EGFR the inhibit thatAgents (EGFR). receptor factor growth epithelial the is CRC of treatment the intargets new promising most the of One treatment. this with limitations remain therechemotherapy, traditional in improvement significant the with Even world. westernthe in death cancer of cause leading second the is (CRC) cancer Colorectal (Maruyama andAoki2006,188) rats and humans, and the REP for human was determined by the toxic dose obtained. ineffect of level same the cause may tissue target the in concentration same the that for dose assumingmodel, PBPK Toxic human a with liver. back-estimation by determined in was human concentration dioxin on targeting extrapolation species inter-for used was model) (PBPK model pharmacokinetic based physiologically A rat was determined using dioxin concentration and the number of the foci in rat liver. tofemale assay SD rats after repeated oral administration of dioxins. The REP formation of dioxin for afoci liver a applied We activity. promotion tumor their on ing focus-(PeCDF), 2,3,4,7,8-pentachlorodibenzofuran and 1,2,3,7,8-pentachlorod-(PeCDD), ibenzop-dioxin (TCDD), potencies 2,3,7,8tetrachlorodibenzo-p-dioxin relative new for the calculated (REPs) we congeners, dioxin three of mixture a of titatively using experimental data and mathematical models. To quantify the toxicity The health risk of dioxins and dioxin-like compounds to humans was analyzed quan- mkn, h ms etniey tde lfsyerltd ik atr o dsae is disease, for factor risk causally associatedwiththesecancers.(Hwangetal.2003,238) lifestyle-related studied extensively most the smoking, F. RussoandJ.Williamson Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 e h st f asl eif ta a aet with agent an that beliefs causal of set the be deter- evidence agent’s torelation causal an the analyses it Second how adopt. should she of beliefs causal which mines account an to primacy gives it First, follows. as epistemology ofcausalityinthehealthsciences.two-foldthe to justice does account integrated of type this how see shall we section thisIn approach. of types two the of purelyaspects involves a account—it difference-making nor account mechanistic purely a neither is which causality of conception aslt isl i dtrie b cua eitmlg (ilasn 05 catr 9, chapter 2005, 2006, 2007a,b). (Williamson epistemology causal by determined is itself causality dichotomy. False, because there is a third way: the way: third a is there because False, dichotomy. falsea is difference-making and mechanistic into accounts monistic of partition dard stan-the because causality, of theories of space the exhausted not have We dilemma. thisof out way a is there But 6). (section several are there fact in when relation causal one have to seem we why concept of cause when in fact we have several, or why we seem to be talking about one explaining of difficulty the plus problems, similar faces difference-making—face epistemological problems (section 5); on the other, pluralismandmechanistic accounts—both monistic hand one the on place: hard a and rock a It may seem that our understanding of causality in the health sciences is stuck between 7. EpistemicCausality problems ofsection5. the other, then with respect to that particular use of the word ‘cause’, it is subject to the ondifference-making or hand, one the on mechanisms of terms in understood is tion be just different relations, some particular use must refer evidence to a single relation. If that the single rela- that possible be should it right, mechanistic, orjustbeprobabilistic. is pluralism if claim: the forevidence of variety the explain can’t pluralist The evidence? probabilistic ample is use is probabilistic, uncontroversial,the and if However, claim? causal established the of support is in cited is mechanism evidence probabilistic further the when even that, be it can how probabilistic, a worse, opensthepluralistuptoobjectionsofsection5. and,inference, fallacious a clearly is This probabilistic. and mechanistic claim, causal ‘smoking is a retical considerations. But the pluralist’s analysis of this claim will be single-faceted, say this claim is multi-faceted, consisting of observed dependencies and mechanistic/theo-forevidence the Now components). or aspects two has that thing one be to causality takesrather but pluralist a not is she otherwise for bothclaim, such not some but be notions must (there these of other or one of terms in out cashes pluralist the that logical problems of monism. If this particular use of ‘cause’ is mechanistic, The epistemic theory understands causal relationships in terms of rational beliefsrational of terms in relationships causal understands theory epistemic The So, while the pluralist may say that different uses of the word ‘cause’ can refer torefer can ‘cause’ word the of uses different that say may pluralist the while So, Suppose that the pluralist advocates two notions of cause, a mechanistic, cause cause 1 of cancer’. But then the pluralist opens herself up to the epistemo- cause 2 . Take any Take . 2 , why are mechanisms invoked as evidence, even when there particular International StudiesinthePhilosophyofScience causal claim, e.g., ‘smoking causes cancer’,causes ‘smoking e.g., claim, causal total epistemi vdne hud dp. Thus adopt. should evidence c theory offers a monistica offers cause cause 1 1 , then , and 167 Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 168 agent’s causal belief state should satisfy the following conditions: (conditions: following the satisfy should state belief causal agent’s the ensuing causal claims to be constitutive of causality itself. Causality just multi-faceted this for epistemology, account since it deems can the relationship between the causality various types of of evidence and theory epistemic their The for dependence). account to connection causal a require not do related mechanistically not evidence against causal connection (two dependent variables that are ontologically but making; mechanisms provide evidence of stability; semantic difference-relationships may provideconcerning evidence statistical provide datasets the cancer: about beliefs variables between relationships provided by medical ontologies, and so on. semantic All these types of evidence will biological the shape causal underlying about the knowledge of some knowledge mechanisms, some level, molecular the at observations containinganother patients, past to relating aobservations have clinical might containing dataset one science cancer in example, For evidence. of kinds of variety a are 2007, sec. 20; Williams and Williamson 2006). In the health sciences it is clear that there causal knowledgeispossible. thenso, If agent. rational omniscient an of beliefs causal the to correspond i.e., facts, causalthe to correspond will beliefs causal rational our closer the know, we more the roughly,that, plausible quite is it but omniscient, be can us of none for unknowable, relationshipscausal renders view a such that thought be might It adopt. should agent omniscientan that anbeliefs the by just are determined themselves probabilities and are evidence, agent’s beliefs probabilistic which to according probability, of view rational agent. This gives a view of causality that is analogous to the objective Bayesian causal relationshipsthemselves. epistemic the under that account the full variety will and have a role in determining rational causal mechanisms, beliefs and hence and dependencies including causality, ofindicators of variety a are there that note to is purposes our for important is What nal, need not concern us here—see Williamson (2005, 2007a) for one kind of account. epistemology is to be fleshed out, and why the resulting causal beliefs are deemed ratio- any causal beliefs that are not warranted by her evidence. The details of how this causal havenot should she (iii) and mechanisms); of knowledge (including knowledge other hud con fr l kon eednis ht r nt led acutd o by for accounted already ( not relationships; non-causal known are that dependencies known all for account should for causes of disease and for effective treatments and public health policies. In thisIn policies. health public and treatments effective for and disease of causes for The health sciences pursue both a cognitive goal and an action-oriented goal in looking 8. Conclusion and howanyparticularcausalclaimcanhavemulti-faceted evidence. A pluralistic account will struggle to explain the apparent unity to our concept of cause one of its indicators will struggle to explain why the other indicators are so important. of this epistemology. On the other hand, a monistic account of causality in terms of just How, then, does evidence constrain rational causal beliefs? Roughly speaking, anspeaking, Roughly beliefs? causal rational constrain evidence does then, How, The epistemic theory of causality can be applied to the health sciences (Nagl et al.et (Nagl sciences health the to applied be can causality of theory epistemic The omniscient an of beliefs causal the with identified be to are relationships Causal F. RussoandJ.Williamson ii ) her causal beliefs should be compatible with herwith compatible be should beliefs causal her ) i ) her causal beliefscausal her ) is the result Downloaded By: [Russo, Federica] At: 12:22 28 August 2007 Bunge, M. 2004. How does it work? The search for explanatory mechanisms.explanatory for search The work? it does How 2004. M. Bunge, References Recherche (UniversitécatholiquedeLouvain)forfundingthisproject. deSpécial Fonds the to and Academy British the to grateful are We Sciences. Health andSocial the in Probability and Causality project the of part a forms research This Acknowledgements from ageneralperspective.pluralismcausal and causality epistemic at closely more looking by direction this in health sciences, would be worth investigating further—Williamson (2007a) takes a thestepin those just not statements, causal all for interpretation epistemic an of viability case there is a certain homogeneity about causality throughout the sciences. Clearly, thethebecause perhaps is that experiment establishes the mechanism and the dependency at the same time, in whichso, If claim. causal a establish to enough is experiment probabilistic and mechanistic both evidence scientistsdonotaimatestablishingdifferentcausalclaims. using in Yet relations. draw causal to about used are inferences knowledge field and theories, demographic or economic studies, Also, background knowledge of various types, e.g., the socio-political context, previous interest.of variables between dependencies for and mixed, or biological social, be can whichmechanisms, for look sciences social The too. diverse very is sciences social the inevidence instance, For domains. other to generalised be can causality interpreting required tocapturethefullcomplexityofcausalevidence. iscausality of account epistemic an Instead, evidence. of type the on depending ones do either because a because either do relations are drawn with the very notion of cause. 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