Cómo evaluar argumentos Douglas Walton

8/3/2019 Cmo evaluar argumentos Douglas Walton

1/24

SCornS:. fu-gumeru:;ul0n in D ia lo gic In te ra ctio n (2 00 5) 5 1- 7.4

DOUGLAS WALTON*

HOW TO EVALUATE AR:GUMENTATION USINGSCHEMES, DLAGRAlvIS"CRITICAL QUESTIONS ANDDIALOGUES

This papcr presems sometools thatcan be u se d. roide nrify J.nilil.} 'Z e< linde valu -ate argumenrarion.The example considered is [he atgumenranon schcme forappeal to expert opinion, along with its set of ma,tching critical questions. It is~hown how aJrg,umefus can be diagrammed to identifY missing premises and toexhibit [he role of [he scheme in the argumentation, The asking of a criticalquestion shifts weight of presnmprion back to the ar~uer so that her argumentis defeated unless the queseion is answered. But there are some problems herethat needw be studied, for some critical quesuons need support before th,eydefeat an argum.ent. One of the main problems studiedis how such anargu-ment C3"" ever be closed off, or cemmitmenc to its conclusion made' final, giventhat ql.lcsti.onjng of i e can go on and on in a ,dialogue. In some case, is argued.a meta -dialogue needs to be inserted te resolve [he issue of which sid,c has theburden of proof.

K e ; 'W ( ) r . d s ~ ,argument fmm expert opinion, commirment rules, formal dialectic,profiles of dialogm::, critical questions, burden of proof, mu~ti-agem systems.defca5ible reasoning, legal argumentation, mctardialogues.


2/24

52

Certain common forms of .argument have been formalized as argumen ~m t i o ' . I 1 1 schemes (Hastings 1963; v a n Eemeren and Groot'endOfU 1984.Kienpo in tn er 19 92; W a i~ Q.nrn 9 9'6 ). E spe cially In rereuill1:g aw e the pre-sumptive schemes, w.heIe the premises do not ~J1tlJply the ccnelusio Reitherby dedu ctive or indu ctiec ~ nfef,(i;:ru .ce .Among th e presumptive a[gu~mentation schemes p,reserued and analyzed ]n (Wa lmn 1996) are suchf a m m < l ! . r types of argumentation as 3.ilFgumem from sig!!->


3/24

5 3

Aristotle identified positive f o .r l l 1 S o f al . 'gumeo[ corresponding V I )many ofthe se d .e feasib~ e argum enrarion schem es in his Top ic s, O n S!)phisticain..,~ ' d nL alline rh " .." t . "" L H1.\~~ U).1 'J1an . .iwetoru:, C lm g rnem tOP]CS \ topM/ or PRi.Celi .. nowever ,the role ofihe top lcs rem ained m arg inal in Jog ic for tw o m illennia(lGen paintner 1997).Perelmanand Olbrero ts- T yteca, in The New Rhetorc (151,(:;9)iden ti-fied and defined :nuany d isri nctive k inds ofarguments used. to c onvin ce arespondent O III.a provisional basis, ArgUlnen~adon schemes are ( l rgumen rforms that represent inferen rial structures of argumen tsused in. everydaydiscourse, and in special contexts like ]ega] argnrnentatioo, scientificargamentaticu, < l : ! ld e sp ecially in At Most .o f us are fam iliar w ith form sof inference like modus pomm and d i s junctive s y U o g _ i s r t t in de du ctiv elog je . 'W hile som e of rhe most common and. interesting argumellradonschem es are ne ithe r deductive nor indu ctive , bu t defeasib le and pre sum p~live, m;;ry net be f a m i l i a l ' with the se .. T o . i ~ . 1 J u ' Q d . u o e them, some back-ground may be u S ie k d . .

Hastings 0963) must be credited with. presenting the first systematicidentification ; ;I i. 1 1 ld .


4/24

OOlJG lAS WALTON

A rgumentatio n S th 'trne fo r Appeal to E xp ert O pin io nMajor Premise: Source E isan ,expert in subject domain S containingp eoposirion A.

Conclusion: A. may plausibly be taken to be tru e (f:aJ:5le ).One can easlly see from the argumeneat ion scheme fm appeal to expenopinion that it rep re5en ts O J . d .e fe as iMe Form . o f argument. Although mereis


5/24

Amueeria: The nex r step is "0 identi fy each stave m entthar is < ' I i . premuse 0ra conclusicn inthe argument by highHghting it.The third step J:S~O merhe software eo draw lines representing each inference from any set ofp remi se ..s ro ~ny conclusion,Consider the fo ,UQwing example of an argument.

The Fat Children&ampkChjldren in North America are unhealthy They are gerdng fane] and. rturer.They are less and Jess phys~ca]1y active. They spend too much [lme on [hecomputer and mn:;hing tdc;vi~uotL They don't waJk or bike to school anymere. When f . h e y are .in school, r h . e y don't spend enough time in the gym. oron the playground, They ear [00. much junk food. Acool'di.ng to Dr. AndrewB~.a'lt , d~['ocl:or of~he Chil.dHe


6/24

DOU'GI..J6 W'..u_mN

(H ) Ac:co.rdingm Dr, A ndrew B last, d irect!O Jrof du e Cihad H ealth ResearchInsti~te, th_~e our of(Wve North A:m.erkan children (aged 5 m 17) earsquanrities of junk food lha.t are not ho"lthy [Of a, c h i l d " . . , opd mal develop-menr.

The nex~ step is 0 0 ' load ~j,is ser of starements into Araucaria as a texr file~where it win appear as text ] 1 1 1 . a box on the ~ef[ of [he screen. As eachstarernent is highHghtedj a elided. letter correspnnding to it w~nappearina. box on the right. The u ser shen drn.'I'II'S~inefrom each (; lrded. n um-ber or numbers to' each 'o[her c'ne ~ h< lifsa conclu sion draw n by inferencefrom them .. 0 floe all the d[ 'cl~d numbers have 'been ' ( .Q,nmecred by lines,the resu l r isan ;ugum em d~agram . The


7/24

5 f

she text of eaoh statement ~,ppe.ars1 ' 1 1 a box. Thereare ~ r u s o a mU!p~eofother features mown in the flil] text diagram below.

Fig. 2: The Full TextArgumentThe m issing prem ise I (O f: An!drew B last isan e xpe 'r~ on childre n's he alth)has been made e:xjpHcitand inserted in a ~]n.kerlar~umem SlJpporthl,g con-clu sion G . A .1ink~ d aq;u rnent is one where both {Oliilm th e premises goeogeeber eo suppor[ a (:000115]01,[,. The other a rgu rne:m :s on the dwagrarn areoonvergem. A conve-.rgent argument ]3 one where each p r e m m s e : fi.Hlcrlonsby ]tse[f as an independent [e3J'sOI!l suppcrtiegthe conclusien,

The m ethod of d isg ramm ing is vezy he lpfu l in a case like the oneabove because i~enables the (u'lIOllyst tn organize the : : n : gmT I J e J ! J . 1 r a d o l 1 l in thegiven case into a. structurein which the propnsirions in ehe arn:g!ume.ntandthe inferential structures of the relations en [hem an! displayed, Such adiag ram is also usefu l for ,t:lu~ :)lUpOseof e v : a h ' 1 ! ~ l I ! i l 1 J J g th e : u : g : ll , l m e l 1 J J ( . W c ; : ' cansee, for exam pte, the role of oondusion G r u n m e :lIfgll. .lmernrnJuion and howG is supported by a m issicg prem ise in an. a:rg1lJ,me .ntfrom expcn opm-ion. Su ppose w e w anted roeve luare th is aU 'g umen~ . How cou ld we do it?The devke of th.ecri tical questions is the most usefisl tool 'We need Wa sk : th e fig.h~ c ritic al qu e stions} ana probe inl]o the suppon fo r tb .e arg u -


8/24

00 UGUt!:i W,uTONI

m ent in a dialogue wirhthe advocate who pUll m e arg um e nt fon-vard.. B utsuppose 'tr.~ at ~ dvocafe is not avai lab le for qu estioe i ng . Stm, "Vie canex~p[esscnricalqnestioas abo ut the argument~ putting it into do uhr U I 1 I . tilthese qu esrions are answ ered , This i s rhe very acr ivhy charac te r is tic . ofalgum em analysis and evaluation needed in cou rses on critical arg um efi-t;1 !( ionand in fo rm a lio g ic .Still, be fore any ve ry firm evalua don of rheargum ent can be atrem peed,m ore q u estions need ~ o h e answered, W ha.r w as [he go';!] of the dialogueof w hich the :; u 'g , umen t was p l 1 l . H ? What b limen of proof should. b e appro-priate for such. a dialogue? The premisesseem plausible eneugh, but theyhave :!lOC reany bee n proved beyond d01!Jb!, or even in any scien tiHe way.Perihor example, [he ;u:!umem was part of an edi"o:rial on healthissues. It cou ld have been ju st a m agazio(; article arguitlgro duo readerstbat chil dren ~ 1 1 L North Am erica. are u nhe alth j' by c1[ing som e m edical evi-dence . Thu s the article cnu ld be de '5cdbed as an atte rn pt to pe rs u ade rh ereader thati ts centralthesis,


9/24

HOW TO EW. :LUhTE .ARC UMENTATEGN 59

are -answ ered . or addre ssed appmprial1dy. the ,argum ent is sub je e r todoubt, and it 1,['lay f a . i l for [h is . l 1 e a S C H . 1 ,Thuseach al'g um en ( diagwm con-tains dia]ogu.e nested within the diligram at subarguments that f it anarg um e ntation schem e .3 ., How to For rnally D e f i n e a DialogueA dialogue , in the paradigm or basic m ode l, has rwo participants, oftenc;;I]iedthe propone~u ~m.d.he respondent, W~]Gtake rum s rrn~ lk ing move s.These m oves tak e the form of speech acts G am bs 19 89 ; Singh] 9 99 ) .. F me x amp le , ::tl 'ik in g < 1 1 . qu,estio]1" asserting < I statement) Or putting fm ward anargum ent ~ r,e ttypk al m oves inthe m ost COJU m oo dialogu es. There areactual. dialogues like parliamentary debates, But a dialogue can also bedefined as a. form al stru ctu re , A dialogue can be defined form a1]y as a. setof participnm s who tale tu rns m ak ing m oves accord ing co v ariou s rules.There is < ' 1 , . set of ru les deH n ing pe.rrl l iuedtypes of m oves, a set of ru les fordetermining when a move is appropriate in l ight of prior moves chat havebeen m ade,


10/24

be a vark:ty of different kinds of dialogues, but he .moadeno serious gener-al a[~emp ' [ to classifY them inre dlff"erenttypes with specified goals.Using the above fermaliaarion of diJ]ogue structure is necessary fo r

dl!cory~but man 'fof the .kinds of actual case-s of dialog!llJ.e we wane tostud.y and evaluate roar be fragm ented and localized in a sm all con versa-tion. For modd~ng such cases, there is anodler structure ~h,;J(~an be a'li'ery usefu l tool. Ir is eaJ].ed the profile of dialogue (Kcabbe 1999). A prl'}-m e of dia~ogue ] : 5 a .re];ll[ilivdysh.on sequence 'of connected m oves wi cil th eproponen t'8 moves paired whh those of the respondent ..The small pro-file of dialogue be low can serve as an illu srratioo. "

B e c : a n J l . ' l e B.ProponentI. Why should I aca-pt A ?

Became C .. Why should] accept B?Do you act.iep~ 'Ei Bthen QDo you accept lfl

3.[ do nuraccept C .it Y e s , .5 . Y e s . Wei] d l!e :fi you must aocept C.In this example, m e propoaenrasked : : 3 1 . why-quesci~.)tIJ.at m e first move. Theresponde,'lJi:'s I1rst m ove ~ . ro reply by PU I t t i . ! . l g fo~ro.a!l argument lry giv-ing a reason why the proponent S'hOl l J . l d commit tn the statement A, A~thedialogu e prcceeds.ehe respondentcontinu es trying to use arg um enr.; to getth e p r-op omm I!Q mmmit to A . He 1JISe5 : 3 1 . ml ldu$ p '( )'1 lem form of .arg um en-ration at m oves 3-5 eo try to get the proponent to comm it to C. It is dearW;;1!i1:is sm tt:e gy is to get ro g e ' t her ro coram irro B,. and ultimately eo A

The small profile of diaJogue ahove looks "logical" in nature, But inaddirion to the ir nm m at]v 'f aspect, profiles also have a descripde aspen.Wh.al t are in e :lf oo lI pro file s o f dialogue Mve been s h o W I 1 J by jacobsandjackson (I9'82} to he useful tools to .ana]pe argumentation sequenees inconversaticnal discou rse . W hen pairs or n-tuples of speech acts like q u es-tienranswer Of offe:r/aoceptldecl[ne at:remnventinnaUy bonded> they :J:recaJ]odadjace ncy pairs. jacobs and Ja.ck son (1'9'82: 122) show~d. how adj a-cency pairs ]]1 a corwersational excha[l ge can be seq uen dally eXpolJlJded eoprodu ce a r.m :g :e of s oc ial]y cons tru cte d :< IFgume ru :ationpatterns. Such stan-dardar.gumef1JJ~atio!,lI. sequences are, ~n eR\eu , profi~ es of dialogue.


11/24

4. Classification of Basic T ype-s of DialogueThis pan of the stu dy beg ins hI" p re se ntiog classification of dH r ' t ! r em typesof dialogu e thoug ht eo be im portant for the study of a[ '~ n1enroJi;ion andrunf01l'mal.WLa.ci.es, .8elQwr.he:re is < I. classification ofsix bask .types of d~aJ.Gguethought to be ~mponan t for me study of :arg um e n{ation: th e p ersu asiontype~ me n .e gotiarion type, the delibersrion o/pe , th e .inquiry type. th e i.n fo r-rnation-seeking ~)e, and. the eristic (purely.oove]'S

IConfikt o r Pe:r.tlJ~dcO ilie r R t:001vtor CI~d fY 'Opinions PaI1t:y Issue:I N ee d ~ o Ha .v e P roo f F i . l i L d i and Vedfy f ' r o \ I ' c (Disprove)

E ' I ' i d e n G C Hypo~hc;si;sI C O l l J f I .i : c ;: ~ of Interests Gc:tWhat Yeu Mo:)[' Rca.sm:mnlc: '

Want Sertlemenc [haltBoth C ~J. U v e\X fi th

I \.{;qj tl irc o r GiveIlnform;;uion.

Exdmnge~.nfclJm~~i.o]l

Dilem rna orr rn .c :~ka l Choicel?ersonal C o . n . m . o r

I

' e o . . . ord i.~a te Goal san.d ActWllli'Ve,rbaU.y[o:] u t Out: arOpponem

D ecid e B es tAvailab le C ou rse ofA c r 1 0 : ! : lR eve al D eC 'per B a l l i so f C O I 'I & lic (


12/24

62 DOUG LA S W ....LTDN '

Persuasion dialogue can be best ideJiltified by citing th e well-knowncri tical d i S{:USil io n type of dialogue analyaed by van Eemeren andGrootendorst (1984,]987, 1992). The goal of th e critical discussion isto resolve a conflict of opinions by rational jljrgumenU!E.iorl. The CQl'lfik[is identified a! the confron tation su .g e , and then the dialogu e proceedsd 'liQ ugh th re eorher stag e s. she opening scage. the argum entation stag eand the dosing stage. There are ten rules fo['the critical discussiongivenin van umcrcn and.Gwotendorst (1987: 284~193), requiring. [he partie-ipants ro de fend [he ir claim s w ith rational argum entation. The criticald iscu ssion has been classified as a rype o f pe rsu as ion di.11ogue and form alm ode ls of different types. ofpersu asicn dialogue have been constru cted .LWabon and K rabbe (1995). On th at an aly sis . O J . leading characteristic ofpersuasion dialogue i~dl"~re~qcdon of com m hm enrs is re asonably , bu t:not compleaely permissive; In eonrrast, the inquiry lYpe of dialogue hasthe defining property of cumulativeness, requiring that when O J . partici-p al1l.~cornm itsro a statem e nt, O l e least ideally;. t h a t commitment shouldnever have m be retracted, Nego[iat ion dialogue is quite difft:fCfH frome i the r persuasion O r inquiry, for the goa] is to proveanything 0 r show itro be (ru e by ra~ional arg!U m ent. The goal is nor co m ak e a deal that bothpan ies can liNe w ith , De l iberail! ion is abo ae w hat co u rse of a.cdo n roadcprin < Ii simarion requiring a choke. A useful f o ] ' m : a 1 model o f dd ibe .r ationdialogu e rhat show s its m oves and Mages has been buil t by Hitcheeck,M cBu rney and P arsons (2001). Carberry (1990 ) has presented an analy-SlS of the structure ofinfo.mnaticm-seeking dialogl le iu coUecdng daraincomp u[]ng. Walton and Krabbe (l99:5) have shown tha { there are alsovari ou sm ix ed dialogu es that com bine featu res of the six basic types" Thedebate. for example, is classifie d: p artly as p ersu asion ty pe ofd ialog ue , bu ralso as containing elements of the eristic d:iallogue>meaning that [he airnis to w in a victory even if it meansusing fallacious arg.umen.tation.Now let's go back to ~ he eh.i1dreo's health e xam p le ag ain. It started our,let's say, as an editorial on heallth issues in a popular magazine . The argu-rnenr could thus be seen as pan of a persuasicn dialogue in which theau thor is adv(u ;:alt]ng the controversial rhesis ~ haJ children in NorthAmerica areunhealtby, The auchor cite s va rious argum ents to SUp'pOl~her thesis, as shown in the fu]] rexr d.iagram for the chi.ld.r-en'shealth a.rglll-menr above. "res umably , however, her argum ent is based on em piricalclaims, finding ahout children. 's heal ti l collected by researchers. As showl~in the a.rgu.ment diagram, pan of the arg.umentatiOlll is based 0 . 1 1 1 . amexplicit appcal rcexpen opinion. The rem aining prem ises also presum~


13/24

HOWro EV&UATE ARGUMENTATION 63

ably have been ro]lected. as medica] data of some son, but SOHKes forthese items of infermaeiou are nor offered by the aurrhor" Of course, theargument is Q I . 1 J l y parr of an ed]todal in a magazine article, It .is not nee-e$s:a:ry fi'orthe author I!Qhave (0 cite SOUJ1C(!S of all data, to cite exact :5:tJ-eistical findings, andtn dOC1JUn~rn how dle findings were collected andwho srands behind them ~1) rnedi ,~] (:xper ts, S dU , as one [des to evaluate[he argument, the context moves hack frem an initial persuasion dia-logu e to am hllJormati.on seeking type ofdialog;uc in which rhe o tf eri.ng o fm edical evidence of som e so rt is presum ed. [I'll 0 rher wO r .os , the re appe~r5ro be a sh if[ from an , i u i tia l p ers u as io n type of d ialog u e I!Oal] anterjnrinfo.nl1atlon-see.king tyjpe of dialogae in which expe.rt sdentific evidenceis p re sum e d to b e a va ila ble .:I . Commamenr Operardons in DIaloguesM uch sradi tiona! th ink ing abou t arg u menrari on ]n ph ilosophy as wen asAI has been based on < 1 BDI [helief-desire-imeution) mode], But therehave been. many d iflf ic;lllitie s w i~h the HO I m ode l. Be lie& : desire s andinre ne icns are psycholog ical S'r':U e 5,and i n . t r y i ] l_ g mana~yze or evaluare~~gl!Jmenradon.. uying to pin down an argue] '>s actual mental stares cal]be quire a hard task. OII I the ether hand, i ' l : is often possiMe to cite texru-a I . evidence to indicate what Sta~ements am ,arg u er h as committed himself(:0. Comm irm enr can be seen as public. In a d ialog ue , . : 0 1 . p'ol![~dpalHbecomes committed to a statement in virtue of having gone "on record"b y asserting it, and I f so 1 1 pubU c record cou ld be kcpr .o f his commie -m enrs in cemmirmenr store . H am blin (1970 ) dc!1neJdI a comroirrnemsro re as a set of stf l i tements attributed. to a participant in. a dialogue basedon the moves he has made in the dialogue, as recorded. As the dialogueproceeds, srarem e nrs can be added to ( his s to re Or deleted from it, accord-in g to th e commiUI ' ! I . eO[r l : ! les"~or examp le , i.f ;;l n a rg u e r asserts a stsre -men t, then [hat statement can be inserted. into her 00mrnitmertt store bym e commitmene rule g ov erning as se rtio ns An argue r can also rerracrco mmirmen t to a seaeem ent, de le ti ng it from her com rn itm en ( s[ore . Asnotedabove, rules for retraetien can. vary for different types of dialogue,It shou]d be dearly r-emgniz.ed that f.or Hamblin (1~'70: 257), com-

mirmcne is northe same as belsef Commirmenr is a nonnative notion,mean ing [hat [he structure of the cUaJogue along with arguer's recordedmoves determines the arguer's cnmmitrnen is. B y making at certain type ofmove in dialogu e. an age fi~ is aueomsrically "bound" Of committed co


14/24

64 DOVGW WlILl fV"

other sratemems implied by the move. On of the prohlems in currentargumentation theory, as shown in the previous section> is eo determinehow argumentation schemes bind . cnm rni tm ent, In deductive fo rma llogic. the truth rable for the n1 arerial condiaional defines the cnndi donsunder which a deductively vahd argument, for example one which hasthe rmulm ponem form, ]s binding.Jf the respondent is committed to thepremisesrhen he must (b y logical necessity) be committed. to the conclu-sion, The conditions for the bindingness of a defeasible argument havingthe form of an argumentarion scheme like appeal to e:xperi: opinion arecomparable, bur are also quite different. These conditions are shown inthe Comm, Table heiow;

Table 3 ;' Th e C omm 14bteCommined to premisesUl'u.?o'mmittccl toeondusion Must commir to conclusiono r ask critical questio n

Committed roconclusion Argument not necessaryCom m im :d to pr-em ise8Un comm i rre d ro p rem ise s Ccmmirred to conclusion

Unmmmi ned 000)[1I:11.18iol1

The comm, table shows the options in a dialogue when a. proponent pursforward a It argument fitting a defeasible argurnen rarion scheme. .F]rstconsider rowone, Suppose me respondenr is already commireed to theconcl usion, Then argu mentation is not necessary, and there is no effecton the respondent's ecmmitment store, Next consider rows three and.four; Suppose the respondent uncommitted to the premises, Whether heis committed to [he conclusion or nor, the argument does not force himto alter his existing commitments. He has the opticn of rep]ying. by sim-ply indkadng he is not oommhred co one of the premises. It Is only inthe remaining row of rhe table, row rwo, I C h ; ; ! J t something significanr has1)0 happen to the respondent's commitments in the dialogue. Here, eitherthe respondent must ask one 'O f [he appropriate critical questions match-ing the argumentation scheme, or he must change his commitment setby becoming committed co the conclusion, Tbus we Can see how argu-mentation schemes have a structure that makes a defeasible argumentbinding on a respondent's cemmiemenrs in : ; ! I . dialogue,


15/24

HOWTD EVALUATE ARGUME:NTAT10t - l 65

AI] problems of commitment management f < H : ' defeasible argumenta-tion in d ialo gu e have not been solved y et h ow eve r, There is still an othe rquestion. What happens in JL dialogue when the respondent runs out ofcritical questions? For example with the appeal to expe rt op in ion scheme,what happens when the respondent has asked all six critical quesrions!Does the respondent then finaill]y have to commit to the conclusion un reo-servedly, or can. he still go on asking ether critical questions? This ques-don expresse,~ the completeness problem f ;or dialogue argumentation.This problem remains unsolved so far. For as indicated in (Walton 1997),there can be subquestinns for each critical queseion matching th e ap pe alto expert opinion. The solution to the p roblem, it seems, resides in dia-logue closure, achieved at the closing stage ofa dialogue, Only then is thepossibility of funher critical questioning cornpletely closed off. I leavethis unsolved problem for future investigations,6. How Argumentation Schemes arc Binding in DialoguesThe argumentation scheme for appeal to expert opinion does not repre-sent a form of :lrgu men r rhar is deducti vely valid. or ind uctively scwng.So man y m~ghtW'Dnder how such an argument f O o r m is hindi ng. 1f youaccept rhe prem ise s, do y O o U do not necessari I .y have ro accept the conclu-sion, or even aocept it as probahly true, You can raise critical questions,If so; many might: say] the argument has does not appear to be bindingon. the reci pien t to whom itwas di recred. So what g:ood is it (hen? Orwhat is . its I ,ogid After all, ifa. structurally correct argumem does not bindthe recipient to amepting th e conclusion, once he accepts the premises,what kind . o f rationality does it have as an argument? To answer this que.5-do n. the connection between the defeas ible argumentation scheme andthe structure of dialogue surrounding it must be clarified. To see how theargumentation works in such a case, let's tum again to the example ofappeal to expert opinion. Suppose the proponent in a dialogue puts for-ward an appeal roexpert opinion to the respondenr, In such a cast: therespondent only has three options at his next move in the dial ogue.L He can q uestion one ofrhe premises.2. He can ask one of the six appropriate critical questions (shown above)

matching '[he scheme.3. He can accept the a..I"gul ue lu (at least tentatively> subject to further

questioning) .


16/24

66

To some, however, this Iisr of options may seem too restrictive. Surely,some might .say~the respondent should have the additional option ofhrrungi ng forward another arguIIJ1Jent- a re .f u~ :a ll io l] designed. 1)0 defeat theapp eal to expert opinion just put forward. Should. the responden r .havethat option or nm~ This qu estion e;x presse s the righr ro lmmedlare lyrebut (ruB) problem. A respondent's fKeooom is detennined by howstrict {tight} Of locse (free) m e dialogue is. In a rigorous persuasion dia-~ogu:e (RPD) .how [he .responJen t mUS[ reply re each previous move bythe other pany is determined by rules that are strict, 0 nly a. restrictedrange of replies is allowed. Ina perm issive persu asion dialog ue (prD)~1 1 ! 1 l 1 1 c hI1!10l'e freedom is ;]!l]owed. In .P.PD, an argue1' is free r o m a k e sever-a f t kinds of speech 3.CtS


17/24

HOWTO IWALUILTE'.ARGUM[NTATION 67

has a problem. How can he "pin down the respondent who alwaysretracts commitments when ir appears that he migh t be in danger of los-ing the argum ent? In (W alta nand K rabbe 1995) th is p rohlcm is deal twith by bring ing in ru les to various versions ofPPD that inhibited rerrac-don, For exam ple em p,;JJge '14 7ff., ru les are given that r-equire stabi Iiry inthe retraction of commitments, These ru les m ak e retraction "sticky",meaning rhac the respondent cannot just retract any single commi tmen tarbitrarjly If [he comrnitmear in question follows (orIn other commit-ments, or is closely related '[0 diem, the respondent may have to retractthese other cemmitmentsfirst.

However . the com plex ity of these stability ru le s m a y su gg esrrhar 3simpler syst!emwould show more dearly how argumentation schemeshave an efe-u on commitment. There could be a simple rule such that if[he respo nden [accerr~ th e premises of the pr-opo nent's argu men t and rh earg.ument is srru ctu rally corre cr (by having the form of a known argu~mentation scheme), then the respondenr sho uld either have to a.ccept theconclusion or he should have the burden of asking an appropriate criti-cal. question. Such a ru le would gendy 60rce th e respondent to rake oncommitments ..Or at least it would preVef l [ him from dodging around byrefusing (0answer , Or go in g off on an irrelevant tangenr. Such a rule is ofcou rse fairly restrictive . and I think. that any system of dialogu e of dia-logue having it would not be as free as a P P D typ e of d ialo gue. But thenir would not be as restrictive as an RPD dialogue either. It would besomewhere in between. It could be called. a QlPD lYpeof dialogue,But there are doub-[Sabout how well QPD would work. One source ofdoubt stems from the defeasibillry of argumencarion schemes (or m. 'myof rhe rn, anyhow ), In such cases, an argument should be subject to defeatif new informacion comes in, late r in the dialogue> that defeats (refines)the argument. But QPD does not seem to be open in this way. Of course,it should only be required that the re spond ent has to tentatively acceptthe conclusion, This seems to leave open the possibility (hat' he could,later retract it,maybe even af"t


18/24

68 DOUGLAS WALTON

provided new , re levant inform arion that de feats the cenclu sion has com e.~ntn the dialogue,The new evidence ru le ' !N 'OU~d. enable argum entation schem es eo IJ boih sides r yp i caUy p u r fu n-v ard. mm1!,. de fe a-sihle arguments. over the course of the dla]ogue.. But a de~easibh: :ngu ~m ent like an appeal co expert opi nion n.onnaU y gives only a sm all wd.gh eof evidence t:or OJ! against the conclusion to be proved globally ]I!1 ilie dia-log)Ue.A ccording to one approach" only when you when you PUt a m assof su ch O 'Irg uO lents of dif fen~I1IJ 'tH nds tG g~ ther at the en.d. of the di.aJoglIJeis a decisive til dng of the burden of proof achieved ...The resol utinn of theissu e in < ' I . dialogu e doe s not g enerally work by p ,i[dng one sing le argu -ment aga.inSI: another opposed a1 'gJument . The outcome is decided at th eend of tbe dia]ogu e" when all re levan targ !ilm ~ fits of diger,en.1: kinds areweighed up togecher .W 11e n con firmted by a si ngle~ l 'gument th


19/24

HOWro EVALUATE ARGUMENTATION

tatinn, this at~ om .e y doe snc ne ce ssarily have ro reply to th e queseionimm e diate ly b yg iv i.ng a n a : p pw p r ia te answer m.at I ! ! 1 I ; ] J i 1 1 c h e she scheme forth e arg umenL Instead she might wel l ] J rese.mt a oou11te r~a :rgumeJ1[ . o r s im-p l y decide I!O leave the critical question uoansw ered , pursu i I 1 I . g a dift,"e.ren.~l ine o f lrguol:e l1 l.tation i!w gem er. Thus to model the k ind of .JJ:[g!U1l1ema~tion typically found in a t[iaI, the QPD type of dialogue is not a good fi~.

What ehese considerationsreveal is that argu.men ration, of ~he kindfOlJ.llld in everyday conversations, or in a erial in law, have a dia]eCtlrnIDstrucm re than is m ore cernplex d13n in i r ia l appearances m ay sugges[. I n atrial, for e ;x _ .a;mp le .ex:aJrJlinll1lg witness represents a different type of dia-LogjIJethan the kind of argumemadon m:edl. hy a lawye r to arrack the argu-mentation . o f m e other side, or eo sum up her case at the enid of th e triaLAnother esamplewould ~e a pacli;JJmen~arydebase on whether to fund ~lliIeconsrrucrien of a new dam project. This type of dialogue would n [ thedeliberation m o del, The parlid]Xlnu have te weight ehe C05t5 and. otherfilc[Qrs and then arrive at a decision om whether to vote for or againstgoing ahead. with m e project. Bu r during ~ t.c debate e :K pe:n:sm ig ht beb rou g ht into g ~ ve l)e -S timo ny~E.ng ru ]le ersmigh t offel testimony; :md . migbtanswer questions and relate a lot ofrelevanr factual infonnation concern-ing dam s, This prooess of q ueseion ing and. in snmecases, ~lI:tehim is based. on embedding of the One d ialog u e in to another.'Io say rha t one dialogue is embedded in another means that [he rwo areS'tru.c~uraLly connecrred. so. that the argum entation in one supportstheargumenearion ~n the ether, In an embedding, the embedded dia]oguehelps til) bringthe aIgJUmen ~adon in [he other ,di:aiog)l;1eowards ~tsgoal .For example, in ;]J conn of law, a p.rmecutln.g amuney nying to persuadea ju ry that a detendanr has com rnitced a crime m ayciee ballistic or DNAe vide nce u si n g: e xpe rt scientific ~ e s[imo ny . In such acase , the sMkcam be


20/24

70

Tb P icture .H anging C ese

an embedding, and the argument based 0 1 ' 1 1 . it can be ql l1ll[e : l iP pro primeand re levanr as evidence in th e trial, S om e sh ifis


21/24

7 1 ,

In the airline case , the re was a shill: from neg.odation d]alogu ew eristicdialogue,

Reed (1998: 249 ) has produced a com pu ting m ethod that C : a J J l be usedeo mode l d ].Je ,L [i~ l shifi!:sfo.rm ally by ]lll.arking th e type of d i:alo .g u e ]nasequence of argumentation. The markers runcl . iG l . . I : e the PO] nus where theslh ikbeg ins and ends,

A kind of sh .ift rhar is very oonu :non in Clomp u ti ng occursin expertsystems where the user needs rn ask [he exper t [0explain somethi IlIg(C3 .w l i ~y>1992) . There is a shift from an expert opinion dialogue, whichis a sp ecial l)'p e of inform a tion-se ek ing dialogue , to an inte real in whkhanom er type of d ialogu e occu rs whe .r> ethe u se r needs to exam ine andd,3Lrif.ywhat the expert meant. Cases of this sou: studied by Grasso,Cawsey and jones (2000 ) show how the solv ing of problem s and appar-enr conflicts in expen adviG e~ giving dialog ue caninvclve a :sh ift eo < ' I . per~suasion dialogue inserval,

In [[I'll! p ic tu re h an gin g case and the PC case, the d ia le ctic al s hif t fromone type of dialogue W another was a good c l l ~ ] 1 g : in that it he lped thea rgumen radon to m ove aJong constructively ..The move to th e seconddialogue


22/24

ncM1dren am-gument. This argumerlt [ooks&irly persuasive, ifQne were voe ncou n re r it in an edirotial. O f course one could. question ~Jh.epremises.Are ch iId.ren really less < 'Ind less physically a:cti.ve? Do chey spend roomuch lime on the comp1!ll!er andwaschingtelevision? To poorvif:0]" dis-pWYie th ese p rem ise s one m ighr co lle ct d ata Or appeal to th e expert opin-ions of the e:xperl'S who .Hud.y such dl~ngs. Su.cff ila move represents a shifrto an informasion-seeking kind of dialogue in which a search ferfacts isundercaken.Buc rhere is one appeal ro expen cpinion ex pl1ddy made in[ f f i l eargumemu. The opinion of Dr.B]aJS[ is d~ed l SLllP paning dle claim ihaJchildren ear WO, much junk food. Blast. it isassumed, is an ,expert. It ]ssaidthat heis director of the C h a d Health Research Institute. Certainlythe argument depends on the premise thaJ[ Blast is r u n . expen: in [he rele-vant dom ain. This missing prem ise has been m ade explicit in rhe fu ll tex targu.men[ d.iagram far the fat ch iJdrel1l argument d.isp.layed above. U acritic questioos whether Blast is.credihle as an expert source, or whetherhis fie ld ~ s in the rig hr dom ain of knowledge, the argum em from c:xpcnopinion is defeated. For the argumem I!O be persuasive,BJ.es credentialsmust he g iven. ow rhe aIg )lunem ceases to be persu asive .. If we don't real-Iy know who Blast is. ,or whe ther he is reaUy a medical doceor, or ac Ieasrhas a Ph.D. ~nsome fi.dd in which children's health falls, the argumentfa il s down. Thus w ith som e critical q u es rions, merely asking th e questionmakesthe argument fall down .. It .1:5not restored until the question hasbeen answered by g i v i I i l g the right triPe of teply;

Som e ofrhe other critical questions are 0.11 a d i f f e r e x H footing how ev-er, If Blast is cited as an eKlPert , because he is a medical decem for exam-ple , it isass um ed that he is personally re liab le asa SOu fCC. If a .qu(!S:tion-f:.f w anrs to aErnck BI.a.t's cre dih il li:y>S ' . a y b y aUegi ng tI]a:~ h.e hasl ied in thepast, or that he has been paid. by a drug cnmpany to say what he said,rhar attack is not ve ry convincing u nle ss back ed up with som e StippOtt-... r e vid .... M "1 ... 'E I ] . ~ . ~ . . . . " ] . . . . '" . 'lL I . ,.Ing eVI_e.I1:Ce.. ere.uy ~ylng JI) ast 1SIDlO[ perrona1 yre]l


23/24

73

while other require further SUpp0l"t. Since there seems 1[00be no universalformula for deciding whi.ch category each critical queseio n shou ld be in.the u lrimate solution may be [I) . i n v G . k e > in some cases" a H 'l J e l : a - d i a . l o g ' l! 1 ' ein which the issue of burden of proof is discussed and resolved ...Once thisproblem has been sol ved, we will be able to evaluate argum ents found ineveryday corrversaeional settings, as wen as being able 11:0 iden ~ : i : f Yand ana-lyze them . Bu~ as shown abo'!,l'e~here em be different d e g H ; ; e s of srricc-ness of rules apprcpriare for diffef,en.~ arguroen[ settings, The complete-ness problem is easier to solve fin: Q[?D dialo.@;!ue.shere any critical ques~don asked. must be answered, or rheoriginal argument is defeated, Inmany instauces 'O f everyday conversstio nal and " e g a l : < I :r g J u m e l '1 l . ~ a d o n > diceQPD model is tOO strict and the PPD model is the better one ..

References

OW..!!EIlRY, S, U990). Phil Rocogoi~io:n iIII Natural Linguage Dialogue, Cambridge:The MlT Press.CAws!':\', A. (1992). IEqll ru~al1;hma"lid [1:l~e.ro_ctilOt Nordl '; 'I ' 'e '>~em Un i i y , e r . s ; L l Y . E l I ' . a n s ' C c m i U inomHfKHOCK . D.;. McBuItr ' - ,JEY. lP :& PARSONS , S. (2001). A From ewotk fot Delibem tioL'JDualogues. [[I,: HANSEN, H. Y .; TrNDI!.lf, C. W .~ BWR, J . A. & JOHNSON, R . H.

(e;ds.)_H. V . Hansen, C. W . TiEluh~,J. A. B l a . u r ; ; U l J R . Ho. johasen, compact d i sk ,Aloo av


24/24

74 DOVGUS WAL1UN

KnP ;NU'O[NTI ' :R , M, (I. 991,). AH[a ,g~ l:ogi l< : Scru kru r und Fu n k E L O I l VO,r! A rg~~men~J.riQn~-flll!S~~!'1j S tu ug J:rt; From f f i3ri-H:,h:ooQg,

l {rEN POINTER, M. (]997). On the Art of Finding Argum~nt:s. kgrJmf'ntatiof1 11 : 225-236.KRARElE, E. C. w . (199'9). Profiles ofDiaJoglle. In : GEBItA[>';lJ)'(,J . lliRX, M., ; D~ R l J K I ,M. & VWi!~, Y. (tlds:,),JFAK: Essays Dedicated to Johll l l l van Bc.i1lmcm 0[1 th.c

Occasion of his 50lh Birthday, Amsterdam: Amsrerdare Unive~i(]' PISS: 2536,PA.RSONS, S. & j[iNNI NGS, N. R (996). Nego daeion [hm'ugh ArguJlIlenr:ai.orl: A

P r e . ! imi.i'~~y Reron. ProcITdingt 4 t IM lmemathm.al CrmiN/lot 011Mi"t;-~mSys temJ (ICMA..S '9 6), K yoto: 26 7-274,

l?:ERlElfl,1i/IiN, C. & OLIlRECH1:-5~ THECA, L (1969'). The New Rhemric, No rre D:am.e:Un U v e r s i r y of No~reDame ~_REE:O, C A t]99S). Oiaioguc Frames in Ag~muCcmmunicarion, In : DE.MAZEV, Y. (00,),

Proceedings of the Third ]ntemationaJ Conference on Muhi.Agcnt Syr;menu, lEEEPress, 246~253,R,fm, C A. & Nm:MAN. T lPO(3). Argll~lelltal;(]n M,lChi~les, Dcrdredrr: K~lI\Oo't;r,Rm::o,C A. & ROWE,G. W. A (2001), AmllG3[ia: Software for P uzzles in Argllmem

D~;agrilmming and ){NIL. Deparrmcnr of Applied Computing, Un!verni c y ofDundee 'Ie chnieal .RepoJ :~\ ! ' a i l ; 1 !b J e ar h~t 'p:!h V ' N l o V . c n J n p l 1 6 n g . d . l l o d e e . a c , u k t s l ' n f f / c r e e < i 1S .ING~- t, MUNINDAR, P ; (19 99 ). A Sem antics for S[p!;tchAots. AnI'W t. o f Math e mati a .ttndArnfiiial bueiliVnI;e, 8::47-71.WAlTON, D. {l992lThe Place ofE.rnmioll iu Alll lurn.em, University Park, Pelln8y1vallia~

renn S~alie Press: 2 : .18.WALTON, D " (19 96 ). ArglHn.el1mt~ol1S ,h t;m~~ f or P :re s:u .mp tiv t: Reasoning, Mahwah, N ,J , : Erlbaurn.WAlTON, D. {I 997). Appeal rn Expen Opinion, Unn\l 'er~ury Il

Cómo evaluar argumentos Douglas Walton

Documents

Transcript of Cómo evaluar argumentos Douglas Walton