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Mind Association

The Very Idea of a Synthetic-AprioriAuthor(s): Norwood Russell HansonReviewed work(s):Source: Mind, New Series, Vol. 71, No. 284 (Oct., 1962), pp. 521-524

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VII.-DISCUSSIONSTHE VERY IDEA OF A SYNTHETIC-APRIORI

THE class of propositions is often trisected as follows: the analytic,the synthetic, and the synthetic-apriori. The status of this thirdentry is in perennial dispute. Is any proposition correctly labeled' synthetic-apriori' ? Or is this very label somehow nonsensical?Perhaps the expression ' P is a synthetic-apriori proposition '.makessense, but is never true since there is no suitable value for the vari-able P.These questions require re-orientation. The thesis of what followsis that ' synthetic-apriori ' does not label a type of proposition at all..Two quite different things are characterized by this designation.Moreover, the idea of a proposition which is at once synthetic instructure, yet justified apriori is not inconsistent. It is just that,as a matter of fact, perhaps there are no synthetic-apriori propositions.Consider the bisection of the class of all propositions along the line'analytic-synthetic '. P is analytic if, and only if, its negation is ofthe form (or leads to something of the form) Q. - Q. Analyticpropositions are thus non-obvious tautologies; their tautologicalcharacter can be revealed by definitional transformations. However,a synthetic proposition is such that its negation, ' P, is not of theform (nor does it entail anything of the form) Q. ' Q.This division is exclusive and exhaustive. The negation of anyproposition must be such that it is either of the form Q. ' Q (orentails something thus formed),-or its negation is not of this form(nor entails anything thus formed).It apparently follows from this that analytic propositions cannotbut be true. Their negations are self-contradictory, i.e. entail anyproposition whatever. And synthetic propositions, since they haveequally well-formed and otherwise meaningful negations, must beadjudged true only in virtue of contingent matters of fact.The knife called ' apriori-aposteriori ', however, cuts the class ofpropositions through quite a different stratum. To characterize aproposition as ' apriori ' is to say nothing whatever about its formalstructure, or the structure of its negation, or consequences derivabletherefrom. It is, rather, to remark the mode whereby the truth ofthe proposition is discovered. A proposition is apriori if its truth isestablished without recourse to any possible experience (past, present,or future). A proposition is aposteriori if, in order to justify itstruth, reflexion alone is insufficient. Some appeal to some exper-ience is required.No detailed defence should be required for wishing to distinguish(1) characterizing the structure of propositions (and their consequen-ces), from (2) characterizing the mode of justification of propositions(and their consequences). One can discuss the analyticity ornon-analyticity of P without considering what appeals must bemade to establish P's truth. (The third paragraph of this paper does

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522 N. R. HANSON:just tliis!) The analyticity-non-analyticityquestion is settled byentertaining ' P, tracingits implications,andfinding(ornot finding)something of the form Q. Q. This kind of enquiry is neutralconcerninghow P is established-or even whetherP is established.Analytic-synthetic,therefore, divides types of propositionalstructures. Apriori-aposteriori, owever,divides types of proposi-tional justifications. These are quite different.Supposeoneidentified 'analytic' with ' apriori ,.e. gave theseterms preciselythe same meaning. Onlythen could the designation' synthetic-apriori' be a contradictionin terms. But, for reasonsgiven above, there are no groundsfor this identification. Indeed, itis difficult o see that any judgmentconcerning he justificationof apropositionfollows logically rom a decision as to its analyticity ornon-analyticity. The dichotomiesare that different.Many levelheaded philosophershave thought peculiar the veryidea of synthetic-apriori ropositions. In whatwouldthispeculiarityconsist? Theconsiderations boveare calculated o suggestthat thepeculiaritycannotreside n the fact that this idea is itself inconsistent.How does one demonstratehat a proposition whose negation isconsistent cannot be justifiedwithout recourseto experience? Tohave learned that a proposition'snegation is structuredthis wayrather than that entails nothing about its mode of justification.Not directly. Crudely put, learningthat a propositionis justifiedaposteriori s to learnsomething n addition othe fact that its nega-tion is consistent. The ideaof a propositionbeing syntheticdoesnot,by itself, rule out the possibilityof its justificationapriori.Above all, ' synthetic-apriori'does not designatea new categoryof proposition. Synthetic-aprioripropositions if such there are)aresyntheticpropositions; propositionswhosenegationsareconsistent,and entail nothing inconsistent. This much alone does not meanthat there are synthetic-aprioripropositions. It suggests,however,that the claim that there couldn'tbe synthetic-aprioripropositionsmay be ill-founded,unless based on much broader,and hence morearguable,philosophical onsiderations. Perhapsthereis not one un-questionablecandidatefor the status 'synthetic-aprioriproposition'.But this may just be a matterof fact, and not a consequence f logic.Let us ask how, in fact, analytic propositionsare justified. Weknowthat P is analytic if and only if its negationis inconsistent(orentails what is inconsistent). Hence, demonstrating that P isanalyticrequiresdoingthe samethings as to show that P is forevertrue. Since its negation is self-contradictory, t could not but betrue-a fact we learn fromlogicalmanipulation,not fromexperience.Even so, since the consequencesof this distinction will bear downheavily in the case of synthetic propositions,I must insist thatdemonstrating 's analyticityis not the same as establishingthatPcouldnot befalse. The operationsof both proceduresmay be iden-tical-but the ends are different.To say that a proposition s analytic is not to say just that it is

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THE VERY IDEA OF A SYNTHETIC-APRIORI 523foreverand alwaystrue. That P is forevertrue follows from(but isnot identical with) the fact that P's negationis self-contradictory.Confusionsresult from failing to make this distinction. Thus,when analytic propositionsare said to be those which areforevertrue andcouldn'tbefalse,the ideaof analyticitycollapses nto that ofinvulnerability. Thus the class of analytic propositions becomespopulated with all sorts of propositionswhich, although felt tobe certainly true, lack self-contradictory negations. Certainphysical principles,religiousutterances,and even some moral pre-cepts have been characterized s analytic solely on the groundsthatthey are invulnerable o disconfirmation. But this locates an acci-dental feature of analyticityas its definingcharacteristic. Ofcourseanalytically true propositionsare invulnerableto disconfirmation.'Thisis because heir negationsare self-contradictory. So questionsaboutwhetherP is analyticremaindistinctfrom questionsconcerninghow P is established. I provethe formerby revealing nconsistenciesin ' P, or in its consequences. The latter issue involves arguingfrom the fact that - P (or one of its consequences) s inconsistentto the conclusion hat thereforeP must be forevertrue. The secondundertaking s differentfrom,indeedpresupposes, he first.This distinctionbecomescritical with synthetic propositions,andfor the point of this paper. WhenI have established hat a proposi-tion is syntheticI have onlyestablished hat its negation s consistent.This is done by almost purely logical means. Justifying the truthof the proposition s quite different n this case. For,'a propositionmay be synthetic whether true or false. P is synthetic if ' P isconsistentas wellas P, of course. Onemust addthis to blockcallinga contradiction,whose negation is consistent, 'synthetic'. Estab-lishingP's truth requiressomethingelse to be done. What?It remains o be shownto me that whatelsemust be doneto estab-lish P's truth can be read off simply and directlyfromthe fact thatP is consistent. But what is logicallywrongwith the idea thatthe class of non-contradictorypropositionshaving consistent nega-tions (i.e. synthetic propositions)divides into those whose truthis justified without recourseto experience(i.e. apriori),and thosewhosetruth is justifiedonly by recourse o experience i.e.aposteriori)?To rule out the formerpossibilityis simplyto shout (withoutgivingreasons)one of the centraldogmasof empiricism,which latter,I needhardlyremark, s nota set of deductiveprinciples. 'But since this isjust what is at issue (i.e. does 'synthetic-aprioriproposition'makesense),the matter thus put need not be pursued.I have no clear notion of what it would be like to justify byreflectionalone the truth of P when - P is consistent. But thismay be only a fact about me. I cannot see how of two equallyconsistent alternative propositions (P and ' P), reflection alonewill determinewhich describesthe facts. But to say this does notprovethat there cannot be synthetic-aprioripropositions. I havebut softly expressedan article of the empiricist's aith, to wit, thatasaworkinghypothesis, t seemsunlikely hat anygenuinecandidatesfor synthetic-aprioritywill be forthcoming. This conjectureis not

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524 N. R. HANSON:justifiableby logic alone. And logic alone cannot demolisha non-empiricists'position.

This discussionmust not be allowed to involve a host of proposi-tions which are at once synthetic (i.e. having consistent negations)and are yet inconceivably false. It is perhapsinvulnerably truethat I cannotbe in two placesat once, that I am now consciousandtyping out these words, that there cannot be a perpetual motionmachine, etc. But while these are both invulnerablytrue and alsosynthetic in form, such propositionswill not serve as candidatesforsynthetic apriority. Their invulnerabilityresultsnot so muchfroma direct, non-experimentaldemonstrationof their truth, but ratherfroman implicit,yet far-flungreference o entiresystemsof empiricalknowledgewhose very pattern dependsupon assumingthe truth ofsuch statements. The invulnerability of a 'genuine synthetic-aprioristatement ' cannot consist simply in pointing out the disas-trous systematicconsequencesof entertaining he negationto such aproposition. The credentials of such a spectacular propositionalentity mustbe set out directlyby reflectiononthe assertionsmade byP and by P.Of propositions which are systematically invulnerable-yet-syn-thetic, there are many examples at the philosopher'stongue-tip.Of propositionswhosenegationsare consistent,but yet whosetruthwill be apparentto anyone who understands hem-I cannot thinkof onesingleexample. But this impliesnothingof logical mportanceabout the idea of a synthetic-aprioriproposition. No mere factaboutwhat I, oranyone,can orcannotdo wouldhave suchan impli-cation.The situation,then, is this: that of all known non-contradictorypropositionswhose negationsare consistent,it is factually true thatthey are establishedby recourse o experience. In otherwords,thatthey are contingent is (in a sense) a factual tiuth about such pro-positions. That they are synthetic is a necessarytruth. That cer-tain claimsare formallystructuredsuch that their negationsare in-consistent is a claim which, if true at all, could not but be true.But that theirjustificationsare contingentuponexperience s a claimof a different kind. This is just a matter of fact. It may besaid to describe only the 'explored regions' of the modes of justi-ficationfor syntheticpropositions. In itself it containsno argumentagainst a propositionwith a consistent negation being justified insome different, possibly non-experientialmanner. We do knowwhat it is likefor somepropositionso be justifiedwithoutrecourse oexperience. With analyticpropositionswe knowwhy such recourseis needless. We are not in the same position concerningsyntheticpropositions. We may not in fact, know how a propositionwith aconsistentnegationcouldbe justifiedwithoutrecourse o experience.But, short of reiteratingthe empiricist'smanifesto (again withoutlogically binding reasons),I know of no strict argumentfor rulingout the very idea of a synthetic-apriori.

IndianaUniversity NORWOODUSSELL ANSON