Musgraves Disagreement With Wittgensteinians on Their Solution to Hume's Problem of Induction

8/12/2019 Musgraves Disagreement With Wittgensteinians on Their Solution to Hume's Problem of Induction

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W I T T G E N S T E I N I A N I N S T R U M E N T A L I S M 77mentalists give in favour of their position, and in particular, infavo ur of the inference-licence view.

There seem to be three of them:(a ) tha t it enables us to sidestep the problem of induction;(b) that i t correctly describes how scientists and others(c) that it has been established by Lewis Carroll.actually argue;

will consider each of these arguments in turn.

2. Defending Wittgensteina) Side stepp ing the problem o induction.

Put very crudely, the first argum ent goes like this: as H um e showed,no general theory can be established as true from observation orexperiment; therefore, general theories are not true (or false)propositions at all. The argument is, of course, patently invalid. Itrests on the hidden assum ption th at a stateme nt can only be true (orfalse) if it can be established as true or false). It rests, we might say,on a conflation of truth with certainty.

N obo dy has put the argument quite so crudely a s this. But Schlickcame quite close to doing so. Schlick read in Wittgensteins Tractatusthat:Suppose that am given all elementary propositions: then can simply askwhat propositions can construct out of them. And there have allpropositions,and that fixes their limits. 4.51)A proposition is a truth-function of elementary propositions. 5 )All propositions are results of truth-operations on elementary propositions.5.3)

All truth-functions are results of successive applications to elementary proposi-tions of a finite number of truth-operations. 5.32)Schlick took the elementary propositions to be observation state-ments, particular statements which can be verified by the senses.As usual, there is some dispute about whether Schlicks under-

standing was correct.) Given this reading, it follows that general


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78 ALAN MUSGKAVEpropositions are not propositions at all, since they are not (finite)truth-function s of elementary p roposition s. O n the verifiability theoryof meaning which Schlick extracted from Wittgensteins Tractatusgeneral propositions are meaningless (neither true no r false):I t has of ten been rem arked tha t , s t r ic t ly , we can never speak o f the absolu teverif icat ion of a law the above-ment ioned fac t me ans tha t a natura l law, inpr incip le, does no t hav e the log ical charac ter o f a s ta tem ent , bu t i s, ra ther , aprescrip t ion for the format ion of s t a t emen t s .Schlick proceeds to sidestep the problem of induction:T h e p r o b l e m of induct ion cons is ts in ask ing for a logical jus t if icat ion ofuniversa l s ta tem ents ab ou t real ity W e recognise , wi th Hu me , tha t there is n ological jus t if icat ion: there can be none, s imply because they are not genuinestatements .12Ech oes of this argum ent a re to be found in o ur later Wittgensteinians.Watson says that expressions like correct and incorrect (and byimplication, true an d false) ar e not applicable to laws of nature,because:I t seems tha t the express ion the co r r ec t law o f na tu re is n o t a proper g ram-mat ica l exp res s ion becaus e , no t knowing how to e s t ab l i s h the t ru th of as t a t emen t employ ing th i s fo rm of speech, we have not given it a meaning.13( W a t s o n 1938,p. 51) Schlick, op. d. p. 151, 156 (see footnote 8). As Popper points out, a similar argu-ment led Carnap to espouse the view that natural laws are not indispensable formaking predictions. C arn ap found that not only could universal laws not be verified,but that in Carnaps system they could not be well-confirmed or probabilifiedeither: in Ca rnaps system the degree of confirm ation, which is identified with the logicalprobability, of a universal law is always zero. Whereupon Carnap eliminated lawsfrom predictive scientific arguments, saying (with Mill) that such arguments reallyproceed from past instances to the next instance. Later Watson subscribes to the logical twin of the verifiability theory of meaning,the doctrine of operaticma/ definition: Me aning is connected with the method of testingthe truth of a statement which employs the expression whose meaning is in question.I t is so in physics. Th e exact meaning to be given to the word length in a statementsuch as The length of this iron rod is 25.30 cm. depends on the degree of precision ofthe method which one has in mind for m easuring it. op. cit . , p. 7 6 ) .The difficulty is,of course, that all measuring techniques being to some extent or other imprecise,precise particular statem ents are no more verifiable than universal statements. Tha t iswhy Watson has to say that as they stand they are not proper statements at all, and


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W I T T G E N S T E I N I A N I N S T R U M E N T A L I S M 79H anso n agrees:Th e expression the co rrect law of na ture is an improper one from a logicalpoint of view. How can we establish the truth or the falsity) of a statementemploying a n expression of this form? W hat w ould cou nt a s evidence one wayor the other? If these questions cannot be answered, then we have given nomeaning to the statement in the first place. And this is precisely what I a ma d v 0 ~ a t i n g . l ~Hanson 1969, p. 324And then there is a curious argum ent, implicit in both Toulmin andHanson, which goes something like this. If laws and principles weretrue or false statements, then because of the logical problem ofinduction we would have to adm it th at n o law or principle could beregarded as established; but some laws a nd principles are established;therefore, laws and principles are n ot tru e o r false statements.that we must interpret, say, The length of this iron rod is 25.30 cm. to meansomething like The length of this iron rod is 25.30fe cm., where e represents thedegree of precision of the method of measurement which the speaker has in mind.

This is reminiscent of Duhems argument that, measurement being imprecise andmeasurements being finite in number, any body of data is consistent with a multiplicityof precise laws, hence none of these laws is true or false). Or of Duhems argumentthat laws cannot be true or false statements because they are all provisional and liableto future overthrow. See Duhem 1954, pp. 171-173.) The truth-certainty conflationis a hidden assumption of all these arguments.l There is a perfectly obvious answer to Hansons secondquestion: what would countas evidence for or against a statement like The correct law of thermal expansion ofmetals is L is, quite simp1y;whatever would count as evidence for or against L .In switching from the stronger question How can we establish . .? to the weakerone What would count as evidence . . ? , Hanson robs the argument of any force i tpossessed.

similar switch pervades Larry Laudans recent defence of the claim that truthor closeness to the truth) is not, and should not be, an aim of science. Laudan slips

constantly from a weak sceptical thesis we cannot demonstrate or kno wfor sure thatany theory is true or close to the truth) to a strong one we can never reasonah1.vpresume or have any confidence that any scientific theory is true or close to the truth):see, for example, Laudan 1977, pp. 125-1 27. This is simply to ignore without argumentthe fallibilist or critical rationalist view that we can reasonablq presume to be truepropositions that we have not demonstrated to be true, propositions which for all weknow for sure might turn out to be false.l 5 This, in essentials, is the argument of Toulmin 1953, pp. 80-83 and Hanson 1969,pp. 331-337. But it is not, of course, stated as straightforwardly as this: for thesubtleties, see below, pp. 102-103.

Toulmin has a further argument which is patently invalid. He points out, against


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80 L N M U S C R A V E

This argument, or cluster of arguments, need not detain us long.Truth and certainty are not the same: it is perfectly obvious that astatement can be true even though we are not, and never will be,certain th at it is true.16 T he verifiability theo ry o f meaning is ju st amistake. And the realist view that scientific theories are true or falsestatements need not be combined with the dogmatist view that weca n know for sur e which is which: there is, as P opper stressed som etime ago, the possibility o f a fallibilist o r critical realism. (See P opp er1963, pp. 97-119; also M usgrave 1977.)N or , we might ad d, is much achieved by side-stepping the problemof induction by advocating the inference-licence view of theories.Humean sceptical questions about the certainty of theories or thereliability of predictions drawn from them, can simply be rephrasedas sceptical questions about the usefulness of inference-licences orthe reliability of predictions drawn according to them. So if an-Mac h, tha t we canno t validly deduc e theories from observ ation reports: . there canbe no question of observation reports and theoretical doctrines being connected inthe way Ma ch thou ght: the logical relation between them ca nno t be a deductive oneo p .cit. p. 41). But later he takes himself to have show n not only that theo riescan not be

deduced from observation statements, but also that o bservation sta tements cannot bededuced from theories (together, of course, with initial conditions). He says as wehave seen, these canno t, as Mac h supposed, be thou ght of a s deductively related oneto anoth er, an d proceeds directly to the inference-licence view of theories o p . cit . ,p. 84 . For the invalidity o f this arg ume nt, see Bartley 1962, p. 30, footnote 1.l 6 Trivialities like this should not need repeating, yet they do. In his article onPopper in the Encyclopedia of philosophy, Hamlyn sums up Poppers view thatcertainty is unattainable in science with the slogan Truth itself is just an illusion(vol. 111, p. 37). Aga in, Kekes writes: T ruth , however, is unatta inable ; the ideal canbe approxim ated, bu t it can never be achieved. Th at this is so follows from w hat hasbeen said u p to now. For to c la im that a theory is true requires that it be provable,and to prove a theory requires the elimination o f the possibility of error. N ot only is itimpossible to eliminate all sources of error, but even if this were accomplished, n obod ywould know that it had been done. (Kekes 1972, p. 304 .

Strangely, even Popp er, while he is protesting Hamlyns misunderstanding, aids an dabe ts it himself, italics an d all: the sentence to which his protesting footn ote is append edreads Thus the idea of t ruth is absolutist , but no cla im can be made for absolutecertainty: we are seekers fo r truth but we are not its possessors. (Po ppe r 1972, p. 46 f . )But we can seek the t ru th and f ind it without being cerrain that we have found i t . Topossess truth does not require that we are cer ta in of i t can p0ssess.a Van Go ghwithout being certain, indeed, without even suspecting, that it is a Van Gogh


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WITTGENSTEINIAN INSTRUMENTALISM 81swering Hume was one of the aims of the exercise, then we mustconclude that the aim has not been achieved.b) Describing how peop le argue.The second argument for the inference-licence view is that it cor-

rectly describes how people argue, because as a matter of psycho-logical or linguistic) fact arguers do not employ theories, laws andgeneralisations as premises in their arguments. This argument goesback to Mill:. o ne set of writers represent the syllogism a s the corre ct analysis of what themind actuallyperforrns in discovering the pro ving th e larger half of the t ruths .which we believe.[But] thou gh there is always a process of reasoning or inference.. . the syllogismis no t a correct analysis of tha t process of reasonin g or inference; which is, o n thecont rary ... of the natu re of induction. (Mill 1879, 11, iii, 1, 5; italics added)Thus Mill concludes that what the mind actually performs is al-ways an inference from particulars to particulars.Wittgensteinians see their task not so much as describing howpeople think as describing how they talk: charting the logical geo-graphy of our concepts, as evinced in the things people say. ThusHarrC writes:But if we pause for a moment to consider the way instantiat ion s actuallyperformed we see that purely logical considerations apart the [deductive]schematizat ions abo ve do not truly represent the pro ces s. Th e natural process ofpredict ion of an instance is to state the instance as a consequence of anotherinstance, for exam ple, th at the creature is herbivo rous follows from the fact thatits a rab bit. T he justification of this move . akes us back to a generalizationo r i ts corresponding condit ional . Thes e are n ot premises since they validatebu t d o not belong in the argu men t that expresses the deduction. (Harre 1960,p. 79 f.; i talics ad ded )The same argument leads to the inference-licence treatment of lawsof nature. Hanson says:l 7 Mill regards reasoning or inferring as obtaining new information from old. Andsince the conclusion of a valid deductive argument is contained in the premises, i tfollows immediately that deductive arguments are not genuine processes of reasoningor inferring. Here Mill was but one of a long line of thinkers which included Bacon,Descartes, and Locke who complained that deductive logic which meant, in effect,Aristotelian logic) was not a genuine logic of discovery.

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Musgraves Disagreement With Wittgensteinians on Their Solution to Hume's Problem of Induction