get tier justified true belief

8/13/2019 Get Tier Justified True Belief

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Is Justified True Belief Knowledge?Author(s): Edmund L. GettierSource: Analysis, Vol. 23, No. 6 (Jun., 1963), pp. 121-123Published by: Oxford University Presson behalf of The Analysis CommitteeStable URL: http://www.jstor.org/stable/3326922.

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ANALYSIS 23.6 JUNE 1963

IS JUSTIFIEDTRUE BELIEFKNOWLEDGE?ByEDMUND L. GETTIER

ARIOUS attemptshave been made n recentyearsto statenecessaryandsufficient onditions or someone'sknowingagivenproposition.The attemptshave often been such that they can be statedin a formsimilarto the following:'(a) S knows that P IFF (i) P is true,(ii) S believesthatP, and(iii) S is justified n believingthatP.

For example,Chisholmhas held that the following gives the necessaryand sufficientconditions for knowledge:2(b) S knows thatP IFF (i) S acceptsP,(ii) S has adequateevidence for P,and

(iii) P is true.Ayerhas stated the necessaryand sufficientconditionsfor knowledgeasfollows:

(c) S knows that P IFF (i) P is true,(ii) S is sure thatP is true, and(iii) S has the rightto be sure thatPis true.I shallarguethat(a) is falsein that the conditionsstatedthereindo notconstitutea siftcient condition for the truth of the propositionthat Sknows that P. The same argumentwill show that (b) and (c) fail if'has adequateevidence for' or 'has the right to be sure that' is sub-stituted for 'is justified n believingthat' throughout.I shallbegin by noting two points. First, in thatsense of' justified'in which S's being justified n believing P is a necessarycondition ofS's knowing thatP, it is possiblefor a personto be justifiedn believinga proposition that is in fact false. Secondly,for any propositionP, ifS is justified n believing P, and P entailsQ, and S deducesQ rom PandacceptsQ asa resultof thisdeduction,then S is justifiedn believingQ. Keeping these two points in mind, I shall now presenttwo cases1Plato seems to be considering some such definition at Theaetetus201, and perhapsaccepting one at Meno98.2 Roderick M. Chisholm, Perceiving: Philosophical tudy,Cornell University Press (Ithaca,New York, 1957), p. 16.3A. J. Ayer, TheProblemof Knowledge,Macmillan (London, 1956), p. 34.121


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122 ANALYSISin which the conditions stated in (a) are true for some proposition,though it is at the same time false that the person in question knowsthatproposition.Case :

Supposethat Smith and Jones have appliedfor a certainjob. Andsupposethat Smith has strong evidencefor the following conjunctiveproposition:(d) Jones is the manwho will get the job, and Jones has ten coins inhis pocket.

Smith'sevidence for (d) might be that the presidentof the companyassuredhim that Jones would in the end be selected, and that he,Smith, had counted the coins in Jones's pocket ten minutes ago.Proposition(d) entails:(e) The man who will get the job has ten coins in his pocket.

Let us supposethatSmith seestheentailment rom(d) to (e), andaccepts(e) on the grounds of (d), for which he has strong evidence. In thiscase, Smithis clearlyjustified n believingthat(e) is true.But imagine,further, hatunknownto Smith,he himself,not Jones,will get the job. And, also, unknown to Smith,he himself has ten coinsin his pocket. Proposition (e) is then true, though proposition (d),from which Smithinferred e), is false. In our example,then, all of thefollowing are true: (i) (e) is true,(ii) Smithbelievesthat(e) is true,and(iii) Smithis justified n believingthat(e) is true. But it is equallyclearthat Smithdoes not know hat(e) is true; for (e) is true in virtue of thenumberof coins in Smith'spocket, while Smith does not know howmanycoins arein Smith'spocket, and baseshis beliefin (e) on a countof the coins in Jones'spocket, whom he falselybelieves to be the manwho will get the job.

CaseII:Let us suppose that Smith has strong evidence for the followingproposition:(f) Jones owns a Ford.

Smith's evidencemight be that Jones has at all timesin the pastwithinSmith'smemory owned a car, and alwaysa Ford, and that Jones hasjust offeredSmith a ride while driving a Ford. Let us imagine, now,that Smith has another friend, Brown, of whose whereaboutshe istotally ignorant. Smithselectsthreeplace-namesquite at random,andconstructs the following three propositions:

(g) Either Jones owns a Ford, or Brown is in Boston;


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CIRCULARITY AND INDUCTION

CIRCULARITY AND INDUCTIONBy PETER ACHINSTEIN

1. DECENTLY' I suggested why an argumentproposed by MaxBlack, which attemptsto supportan inductive rule by citingits past success,suffers rom circularity.The inductiverule underdiscussions this:R: To arguefrom Most nstancesof As examinednder widevariety fconditionsavebeen to (probably)ThenextA tobeencounteredillbeB.

The argument n favour of the rule is as follows:(a): In most instancesof the use of R in argumentswithtruepremissesexamined n a wide varietyof conditions,R has been successful.Henceprobably):In the nextinstance o be encounteredof use of R in anargumentwith a truepremiss,R will be successful.

I The Circularityof a Self-SupportingInductive Argument , ANALYSIS,22.6 (June 1962).

123(h) EitherJones owns a Ford, or Brown is in Barcelona;(i) EitherJones owns a Ford, or Brown is in Brest-Litovsk.Each of thesepropositions s entailedby (f). ImaginethatSmith realizesthe entailmentof each of these propositionshe has constructedby (f),and proceedsto accept(g), (h), and (i) on the basis of (f). Smith hascorrectlyinferred(g), (h), and (i) from a propositionfor which he hasstrong evidence. Smith is thereforecompletely justifiedin believingeach of these three propositions. Smith, of course,has no idea whereBrown is.But imagine now that two further conditions hold. First, Jones

does notown a Ford,but is at presentdrivinga rentedcar.And secondly,by the sheerestcoincidence,and entirelyunknown to Smith,the placementioned n proposition h)happensreally o be theplacewhere Brownis. If these two conditions hold then Smith does notknow that (h) istrue, even though (i) (h) is true,(ii) Smithdoes believe that (h) is true,and(iii) Smith is justified n believingthat(h) is true.These two examplesshow thatdefinition a) does not statea suffiientcondition for someone'sknowinga given proposition. The samecases,with appropriatechanges, will sufficeto show that neither definition(b) nor definition(c) do so either.WaynetateUniversity

get tier justified true belief

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