Carnap the Unity of Science Lite

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Thoemmes Press 1995

Published in 1995 byThoemmes Press11 Great George StreetBristol BS1 5RREngland

ISBN 1 85506 391 3

This is a reprint of the 1934 Edition

Publisher's NoteThese reprints are taken from original copies of each book.In many cases the condition of those originals is not perfect,the paper, often handmade, having suffered over time andthe copy from such things as inconsistent printing pressuresresulting in faint text, show-through from one side of a leafto the other, the filling in of some characters, and the breakup of type. The publisher has gone to great lengths to ensurethe quality of these reprints but points ou t that certaincharacteristics of the original copies will, of necessity, beapparent in reprints thereof.


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best known are Th. Gomperz (1869-80) 1 ,the translator of J. S. Mill, Mach (Privatdozent 1861-4, Professor 1895), andBoltzmann (Mach's successor, 1902-6).Parallel to the work of these men were theattempts made to reform the traditionalLogic of Aristotle and the Scholastics, ofwhich the beginnings can be seen inBalzano (especially in the W issenschajtslehre, 1837), and a fuller development inBrentano (Professor of Philosophy in theTheological Faculty, 1874-1880, afterwards Dozent in the Philosophical Faculty)and Hofler (1853-1922). Of the manywho took an active part in the philosophical discussions of Brentano's circlein the late Nineteenth Century, we maypick out von Meinong (in Vienna 1870-82,afterwards Professor at Graz).Subsequently, the most effective influences on this trend of thought werethe researches, in Logic and the Foundat-ions of Mathematics, of Russell and othersof the ' logistic ' school2 (especially throughPrincipia Mathematica, 1910). Russell'sinfluence has been since reinforced by

1 Th e dates given refer in each case to th eperiod spent in Vienna.

II Cf. M. Black, The Nature ofMathematics, p. 7an d pp . 15 ff. for an account of these theories.8


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for this book appeared in Erkenntnis(Vol. ii, 1932, pp. 432-465) under the title"Die physikalische Sprache als Universalprache der Wissenschaft ", and has beenrevised, by the author, for this edition.

An authoritative statement! of theprogramme of the Viennese circle declaresthat it s outlook is " characterized, not somuch by special assertions, as by it sfundamental attitude, its point of viewand by the direction of its researches.It s goal is unified Science : it s endeavoursare to relate and harmonize achievementsof individual researchers in the variousbranches of Science. From this choice ofsubjects arises the emphasis on collectivework ; hence also the prominence allottedto communicable knowledge ; these aimsinspire the search for a neutral system ofsymbols, free from the dross of historicallanguages, the search for a completesystem of concepts. We strive for orderand clarity, reject all dim vistas andfathomless depths. In Science there areno ' depths ', all is on the surface . . . thescientific outlook knows no insoluble riddles. Analysis of the traditional problems

1" Die Wissenschaftliche \Veltauffassung. De rWiener Kreis", p. 15.10


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Wittgenstein's 1 From Mach comes, bydirect descent, that belief in the value ofgroup activity which has marked the workof the Viennese circle ; from him, also,and by indirect influence through Russell,those elements of Pragmatism alreadypresent, by implication, in Wittgenstein,which go far to mitigate the asperities ofa marriage between Empiricism andSolipsism. I f legitimate, the results ofthis union are of the highest importance ;for it has fallen to many to exorciseMetaphysics from Philosophy, but it hasbeen left for the Logical Positivists, as theyare sometimes called, to behave as if theyhad succeeded. It is not for the trans-lator to estimate their success, or to robthe reader of the pleasures either of in-vective or applause. But professionalphilosophers, who have heard with un-failing equanimity their treatises describedas compendia of ' nonsense ', may beinterested to find here detailed and ingeni-ous arguments for refutation ; and scient-ists, who have always found time for a

1 By Wittgenstein's opinions I mean alwaysto refer to th e views expressed in TractatusLogico-Philosopkicus. In the absence of anysubsequent writings it is not ye t possible to sa yto what extent these views have since beenrevised.12


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their most constructive contributions;here also should be the origin of theirdivergence from Wittgenstein. For thelatter, also, establishes criteria of sense,purges Philosophy of Metaphysics andseparates both from the Sciences; but withdifferent consequences.

3. The notion. of sense. The theory ofTractatus Logico-Philosophicus centresround the notion of I sense ', whose specification is linked with and reveals that conception of the essential structure oflanguage on which is based the doctrineof the untenability of traditional philosophy. Since the sense of statements isdefined in terms involving reference to atomic ' statements, or 1 atomic ' facts,the latter notion is the hub of Wittgenstein's account. The same notion receivesa distinct modification in the theories ofthe Viennese circle.

In the Tractatus the world (i.e. thesubject-matter of philosophical analysis)is conceived to consist ultimately of simpleirreducible 1 objects', occurring in complex arrangements or I configurations',and thereby constituting facts or states of

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below). Rejection of the metaphysicalpresuppositions of the Tractatus is thenpursued to the extreme limit of excludingall reference to the 'content' of statementsand the practice of a special 'formal '1mode of speech from which al l such reference has been eliminated. The absenceof the doctrine of atomic facts permits theretention of a wider criterion of verifiability in sense experience while allowinga pragmatical sense to general statements,natural laws and hypotheses. This solution brings it s own difficulties; it blurs thevery definite outlines of the notion ofstructure in Wittgenstein and leaves truthin an uncomfortable half-way housebetween correspondence and coherence.For if the truth of statements is provisionalsome account is needed that does not maketheir truth dependent on human convenience or human prejudice. This is thedifficulty that earlier Pragmatism hadto meet and could never answer satisfactorily. For Logical Positivists also, itis a pressing question, but the absenceof a final answer cannot detract from theexceptional interest and importance oftheir work.

1 Cf. also R. Carnap, " On th e Character ofPhilosophical Problems", Philosophy of Science,I, pp . 5-19, 1934. 20


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by Idealists, Utilitarians, Intuitionists,etc. Here again we reject the questions themselves in view of theirmetaphysical character. (The case isotherwise in psychological or sociologicalinvestigations of the actions and moraljudgments of mankind ; such a method iscertainly both unobjectionable and scientific, but its results belong to the empiricalsciences of Psychology and Sociology, notto Philosophy. I t is better to avoid theterm ' Ethics ' for such investigation inorder to avoid confusion with normative orregulative Ethics.)As against the preceding subjects, ourown field of investigation is that of Logic.Here are to be found problems of pureLogic, i.e. questions relating to the construction of a combined logical and mathe-matical system with the help of symbolicLogic. Further, the problems of appliedLogic, or the Logic of Science, i.e. thelogical analysis of terms, statements,theories, proper to the various departmentof science. Logical Analysis of Physics,for example, introduces the problems ofCausality, of Induction, of Probability, theproblem of Determinism (the latter as aquestion concerning the logical structure

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Philosophy can also be subjected to thesame treatment. The result is to revealthe absence of that logical relation (ofimplication) to empirical statements and,in particular, to protocol statements,whose presence is a necessary conditionfor the verifiability of the statements inquestion and is therefore usually, and withjustice, required in the findings of allscientific procedure. All statements belonging to Metaphysics, regulative Ethics,and (metaphysical) Epistemology havethis defect, are in fact unverifiable and,therefore, unscientific. In the VienneseCircle, we are accustomed to describe suchstatements as nonsense (after Wittgen-stein). This terminology is to be understood as implying a logical, not say apsychological, distinction ; its use isintended to assert only that the statementsin question do not possess a certain logicalcharacteristic common to all properscientific statements ; we do not howeverintend to assert the impossibility ofassociating any conceptions or imageswith these logically invalid statements.Conceptions can be associated with anyarbitrar ily compounded series of words; and

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views are related, in similar fashion, tothose of Empiricism, since we follow thattheory so far as to reject a priori judgments; Logical Analysis shows that everystatement is either empirically verifiable{i.e. on the basis of protocol statements),analytic, or self contradictory. On thisaccount, we have at times been classified,both by ourselves and by others, asEmpiricists.

The following article is an example ofthe application of Logical Analysis toinvestigating the logical relations betweenthe statements of Physics and those ofScience in general. I f its arguments arecorrect, all statements in Science can betranslated into physical language. Thisthesis (termed 'Physicalism' by Neurath)is allied to that of Materialism, whichrespectable philosophers (at least inGermany, whether in other countries alsoI do not know) usually regard withabhorrence. Here again it is necessaryto understand that the agreement extendsonly as far as the logical components ofMaterialism ; the metaphysical components, concerned with the question ofwhether the essence of the world is material or spiritual, are completely excluded

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ADVICE TO TH E READER.Some of th e words of most frequent occurrencein th e following paper are unfortunately withoutexact English equivalents; th e translationsadopted are likely to be misleading withoutsome explanation.

'Determination' (for ' Bestimmung ') :a description,or any indeterminate sym-bol whose exact value(usually numerical) isobtained as th e result ofdefinite operations,or th e result of such operations.Singular itatement (for ' Einzelsatz ') : state-ments describing particularstates of affairs in contrast

to general statements.Physical language is used technically and doesnot denote th e terminologycustomary in Physics(cf. p. 95).Nonsettse (or pseudo-espression) is intended tocarry none of it s usualabusive connotation. Tech-nical use = whatever can-no t be verified in experi-ence.

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The basis of these various divisions isno t merely convenience ; rather is theopinion generally accepted that the varioussciences named are fundamentally distinctin respect of subject matter, sources ofknowledge and technique. Opposed tothis opinion is the thesis defended in thispaper that science is a unity, that allempirical statements can be expressed ina single language, all states of affairs areof one kind and are known by the samemethod.Very little will be said here concerningthe nature of Philosophy and the formalsciences. The author's views on this pointhave already been sufficiently explainedby others on several occasions. Detailedattention will however be given to thequestion of the unity of the empiricalsciences.

It is to modern developments in logicand particularly in the logical analysisof language that we owe our present insight into the nature of Logic, Philosophyand Mathematics. Analysis of languagehas ultimately shown that Philosophycannot be a dist inct system of statements,equal or superior in rank to the empiricalsciences. For the activity of Philosophy l

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A is not black ' the compound statementno longer conveys any information at all.I t is a tautology, i.e. is verified by allcircumstances. From such a statementno knowledge of the properties of thething A can be derived. Theorems inLogic and Mathematics have, nevertheless,in spite of tautologous character and lackof content, considerable importance forscience by virtue of their use in transforming statements having content. Forthe present thesis it is important toemphasize that Logic and Mathematics aresciences having no proper subject matteranalogous to the material of the empiricalsciences. Postulation of ' formal ' or' ideal ' objects to be set against the ' real 'objects of empirical sciences is unnecessaryin the theory here briefly sketched.

Statements having content, i.e. statements, as is usually said, expressing somestate of affairs, belong to the field ofempirical sciences. Our chief question iswhether these statements, or to speakmore conventionally, whether the statesof affairs expressed by such statementsare divided into several mutually irreducible kinds. The traditional answeris in the affirmative ; and it has been

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matter of such branches of knowledge,the Geisteswissenschajten as Germans say,whether they are 1 significant forms ' orsystems of values, are of a nature funda-mentally different from the subject matterof natural science and cannot be under-stood by the methods of natural science.As to the nature of Psychology widelydivergent views are prevalent. Experi-ments are made, measurements oftentaken of factors capable of quantitativedetermination. Many psychologists there-fore include their science among the naturalsciences, bu t while doing so accentuatethe difference between their respectivesubject matters. Psychology, they say,deals with the ' psychical ', with thephenomena of consciousness, perhapsalso of unconsciousness, while othernatural sciences treat of the ' physical '.Other psychologists, again, lay the em-phasis on the relation between theirscience and the moral sciences. InPsychology also, they say, knowledge isgained by ' understanding' and empathy.The difference consists in the fact thatPsychology does not deal with works of ar tand institutions, as Ethics and Sociologydo, but with the regularities to be found

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the language). The alternative formulation is permissible provided the writer andthe reader are clear that the material modeis only a more vivid translation of theprevious description in the formal mode.I f this is forgotten the danger may ariseof being diverted by the material mode ofspeech into considering pseudo-questionsconcerning the essence or reality of theobjects mentioned in the definition ofa language. Nearly all philosophers andeven many Positivists have taken thewrong turning and gone astray in thisway.As an examplewe may take the languageof arithmetic. In the formal mode, thisparticular language might be characterized as follows :-Arithmetical statements or sentences arecompounded of signs of such and sucha kind pu t together in such and such a way;such and such (specified) rules of transformation apply to them.Alternatively, using now the materialmode, we could say :-

Arithmetical thorems state certain properties of numbers and certain relationsbetween numbers.Though such a formulation is inexact

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We will call a language a universallanguageif every sentence i f it can describecan be translated every state of \into it, affairs, Jand if this is not the case, a ' part ial ' llanguage. The language of economicsis a 'partial language since e.g.a theorem in phy- the state of ansics concerning the electro-magneticvectors of an elec- field in some regiontro-magnetic field cannot be describedcannot be trans- in economic terms.lated into the lan-guage of economics.3. PROTOCOL LANGUAGE.

Science is a system of statements basedon direct experience, and controlled byexperimental verification. Verification inscience is not , however, of single statementsbu t of the entire system or a sub-systemof such statements. Verification is basedupon ' protocal statements ', a term whosemeaning will be made clearer in the course offuther discussion. This term is understoodto include statements belonging to the basicprotocol or direct record of a scientist's (saya physicist's or psychologist's) experience.

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such and such kinds (e.g. copper wire';the statement should be restricted perhapsto a thin, long, brown body ' leaving thecharacteristics denoted by ' copper ' to bededuced from previous protocols in whichthe same body has occurred) : here nowpointer at 5, simultaneously spark andexplosion, then smell of ozone there ".Owing to the great clumsiness of primitiveprotocols it is necessary in practice toinclude terms of derivative applicationin the protocol itself. This is true of thephysicist's protocol and true in far greatermeasure of the protocols made by biologists, psychologists and anthropologists.In spite of this fact, questions of the justification of any scientific statement, i.e.of its origin in protocol statements, in-volve reference back to the primitiveprotocol.

From now onwards protocol statements' will be used as an abbreviation for statements belonging to the primitiveprotocol ' ; the language to which suchstatements belong will be called the' protocol-language '. (Sometimes alsotermed language of direct experience ' or' phenomenal language ' ; the neutral term'primary language' is less objectionable.)

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the second of the answers given above.The third view in our classification is notoften held to-day; it is however moreplausible than it appears and deserves moredetailed investigation, for which this ishowever not the place.Statements of the system constitutedby science (statements in the language ofthat system) are not, in the proper senseof the word, derived from protocol statements. Their relation to these is morecomplicated. In considering scientificstatements, e.g in physics, it is necessaryto distinguish in the first place between' singular ' statements (referring to eventsat a definite place and time, e.g. ' thetemperature was so much at such and sucha place and time ') and the so-called ' lawsof nature ', i.e. general propositions fromwhich singular propositions or combinations of such can be derived (e.g. ' thedensity of iron is 74 (always and everywhere '). In relation to singular statements a ' l aw' has the character of anhypothesis; i.e. cannot be directly deducedfrom any finite set of singular statementsbut is, in favourable cases, increasinglysupportr:-d by such statements. A singularstatement (expressed in the vocabulary

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statements in the manner described above.The question whether each person has hisown protocol language will be discussedlater. For the present A's own protocollanguage will be referred to as ' the 'protocol language.Whenever the rulesof transformationstate the conditionsunder which statements in the protocol language can bededuced from astatement p, it isalways possible, inprinciple, for A toverify p. WhetherA can actuallydo this depends onempirical circumstances. If, however, there is nosuch inferential relationship betweena statement p andstatements of theprotocol languagethen p is not verifi-

I f a state of affairsdescribed by p canbe reduced to factsabout given, i.e.direct, experience ofA, A has in theorythe possibility ofverifying p. A thenknows the ' sense 'of p, for the' sense'of p, or what isexpressed by p, consists of the methodof verification, i.e.in the reduction tothe given. I f somestatement p is notin this inferentialrelation to statements concerningthe given, p cannotbe understood by

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'1] inter-subjective (for those persons). A

statement p, which is inter-subjective (forcertain persons), is said to be inter-subjectively valid if pis valid for each person,i.e. if it is supported, in sufficient measure,by the protocol statements of each suchperson.

I t will be proved in the following paragraphs that the physical language isinter-subjective and can serve as a univer-sal language, i.e. as a language in terms ofwhich all states of affairs could be expressed. Finally, an attempt will bemade to show that the various protocollanguages also can be regarded as partiallanguages, in the sense defined above, ofthe physical language.4. THE PHYSICAL LANGUAGE AS AN INTER-

SUBJECTIVE LANGUAGE.The physical language is characterized

by the fact that statements of the simplestform (e.g. the temperature of such andsuch a place at a specified time is somuch),attach to a specificset of co-ordinates(three space, one

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express a quantita-tively determinedproperty of a

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we are neglecting the coefficients of probability which occur in the physical state-ments). We wish however to interpretthe term ' the physical language ' so widelyas to include not the special linguisticforms of the present merely but also suchlinguistic forms as physics may use in anyfuture stage of development. I t may bethat physical position will eventually bedetermined by more or less than fourco-ordinates; perhaps it will not be possibleto regard the co-ordinates simply as tem-poral and spatial magnitudes. Suchmodifications are of no importance forpresent purposes. The physical languagewill certainly continue to be so constitutedthat every protocolstatementcomposedentirely of wordswhich can be (quitecrudely) describedas sensation-, perception-, or thingwords, can be translated into it .

that every fact ofperception in everyday life, e.g. everything that can belearnt about lightor material bodies(in the naive interpretation) can beexpressed in thephysical language.

This property of physical language issufficient for our further discussion. I t is54


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a physical state-ment containingthese determina-tions is correlatednot only with state-ments containingthe correspondingdetermination in theauditory field butalso under certainconditions withstatements contain-ing determinationsfrom other sensoryfields.

the presence of suchoscillations can bedetermined not onlyby auditory sensations (the sound ofsuch a note) butalso, with the helpof suitable instruments, in the formof visual and tactilesensations.

There are no coefficients of physicalstate exclusively correlated with quantita-tive determinations in a single specificsensory field. This is a fact of fundamentalimportance. For any qualitative determination in some sensory field, we candetermine, with the help of qualitativedeterminations from other sensory fields,the class of the correlated physical determinations. As shown by the illustrationused above, qualitative determinationsin the auditory field can be translated intophysical statements of a particularly

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by the position of the corresponding linein the spectroscopic image. The coloursof the spectrum are redundant in theimplied experiment since a photographwill furnish all the information required.Hence a person completely blind to colourscould still establish frequencies occurringat a definite position in space-time. Sofar, we have remained inside the regionof visual sense, but it is possible to extendthis reasoning to other senses. It wouldbe possible for example to build into thespectroscope an electrical apparatus forexploring the spectrum, so constructedthat a radiation of sufficient intensity setinto motion a pointer which could be feltor a microphone which could be heard.By such means a person completely blindwould still be capable of determining thefrequency of an electro-magnetic oscillation.

From these arguments follows thetheoretical possibility of establishing results of the following three kinds :-1. Personal determinations: A can discover:which physical de- under which physitermination (or class cal conditions he exof physical deter- periences a definite

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there can (or even must) be anothernon-physical interpretation. I t will beshown later that there are objections tosuch a non-physical interpretation, andthat, in any case, the language of qualities,when so interpreted, is not inter-subjective.

I t will also be demonstrated that allother languages used in science (e.g.Biology, Psychology or the social sciences)can be reduced to the physical language.Apart from the physical language (and itssub-languages) no intersubjective languageis known. The impossibility of an intersubjective language not included in thephysical language has certainly not yetbeen proved ; there are however not theslightest indications to suggest that sucha language exists. Further, not a singledetermination, of any kind, is knownwhich, established intersubjectively, isincapable of translation into the physicallanguage.

I t is a just demand that Science shouldhave not merely subjective interpretationbut sense and validity for all subjects whoparticipate in it. Science is the systemof i n t e r s u b j e c t i ~ : e l y valid statements. I four contention that the physical language

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term reduces it tophysical terms. type in a specifiedperson or, more generally still, of suchevents in any person. In other words,every psychologicconcept refers todefinite physicalproperties of suchphysical events.

The problems raised by these statementsare to be dealt with in another paper andwill therefore not be discussed further inthis place. 1I f the assertion of the possibility oftranslating psychological statements intophysical language is well grounded, the

truth of the corresponding assertion concerning the statements of (empirical)Sociology easily follows. Sociology isunderstood here in its widest sense toinclude all historical, cultural and economicphenomena ; but only the truly scientificand logically unobjectionable statementsof these sciences belong to this classification. The sciences mentioned often intheir present form contain pseudo concepts,

1 Carnap, " Psychologic in physikalischerSprache ", Erkenntnis, iii, 107-142, 193..


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taken that the statements expressed aresuch as might also be expressed in theformal mode. That is the criterion whichdistinguishes statements from pseudostatements in Philosophy. [Although thedanger that pseudo-questions may arisein using the material mode is alwayspresent, the contradictions can be avoidedby using the material terminology mon-istically, i.e. by speaking exclusively ofthe content of experience (in the spirit ofsolipsism) or else exclusively of physicalstates (in the spirit of materialism). If ,however, a dualist attitude is adopted,as is customary in philosphy, if one speakssimultaneously of ' content of experience 'and ' physical states ', (' matter ' and'spirit' , 'body' and 'soul', 'mental'and 'physical', 'acts of consciousness'and' intentional objects of consciousness')then contradictions are unavoidablel.\Vhcn all contradictions and pseudoquestions have been eliminated by usingthe formal mode, the problem still remainsof analyzing the reciprocal inferentialrelations between physical language andprotocol language. \Ve have previouslymentioned that if a sufficient number ofphysical statements are given, a statement

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but it can be formulated in other expressions of the physical language which arejust what we require. Let us, e.g. denoteby I seeing red ' that state of the humanbody characterized by the fact that certainspecified (physical) reactions appear inanswer to certain specified (physical)stimuli. (For example ; Stimulus ; thesounds I What do you see now ? 'reaction : the sound, I red '. Stimulus,the sounds, 'Point out the colour you havejust seen on this card'; reaction: thefinger points to some definite part of thecard. Here all those reactions must becounted that are usually regarded asnecessary and sufficient criteria for anyoneto be I seeing red now'). I t is true thatwe do not know the numerical distributionof the physical coefficients which characterize the human body in this state of' seeingred' bu t we do know many physicalevents which often occur either as cause(e.g. bringing a poppy before the eyes ofthe person concerned) or as effect of sucha state. (Examples of effects : certainspeech-movements ; applying a brake incertain situations.) Hence we can firstrecognize that a human body is in that

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describes the physical state of S's body.In other words there is a correlation between S's protocol language and a veryspecial sub-language of the physical language. This correlation is such that ifany statement from S's protocol language is true the corresponding physicalstatement holds intersubjectively andconversely. Two languages isomorphic inthis fashion differ only by the sounds oftheir sentences.On the basis of this isomorphy we cansay the protocol language is a sub-languageof the physical language. The statementpreviously made (in the material mode atthe time), that the protocol languages ofvarious persons are mutually exclusive,is still true in a certain definite sense :they are, respectively, non-overlappingsub-sections of the physical language. The reciprocal interdependenceof the various protocol languages whichcould not be explained in terms of theprevious material account is now seen tobe a result of the rules of transformationinside the physical language (includingthe system of natural laws).

I f the result thus obtained, of the88


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question of the relation between theprotocol statement p to the correspondingphysical proposition P 1 where both areabout physical objects. Let us choose pto be " A red sphere is lying on the tablehere " and, for P v " A red sphere (i.ehaving certain physical properties) is lyingon the table ". p has not the same contentas P 1, for it is possible to have an hallu-cination of a sphere when there is none onthe table, or, conversely, the sphere can beon the table unseen. But p has the samecontent as another physical statement P 1,viz. " S's body is now in physical situationZ ". The situation Z is specified by variousdeterminations including e.g. (1) Thestimulus " What do you see ? " is followedby the reaction consisting of the move-ments, etc. belonging to the sounds ' a redsphere on the table ' ; (2) I f a red sphereis laid on the table and Sis put in a suitablesituation Z occurs. P 1 can in certaincases be inferred from P 2 ; this necessitatesusing the definition of Z and suitablenatural laws. The argument is from aneffect to an habitual cause as used bothin Physics and in everyday life. Since P 1can be inferred from p (because they havethe same content), P1 can be indirectly

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fact that we are referring to a thesiswhich speaks simply of the logicalpossibility of certain linguistic transformations and derivations and notat all of the ' reality ' or ' appearance '(the 'existence ' or the 'non-existence')of the ' given ', the ' mental ' or the' physical '. Pseudo-statements of thiskind occasionally occur in classical formulations of Positivism and Materialism.They will be eliminated directly they arerecognized as metaphysical admixtures;this is in the spirit of the founders of thesemovements who were the enemies of allMetaphysics. Such admixtures can beformulated only in the material mode andby eliminating them we obtain Methodical Positivism and Methodical Materialismin the sense defined. When the two viewsare so purified they are, as we have seen,in perfect harmony, whereas Positivismand Materialism in their historic dress haveoften been regarded as incompatibles. 1

Our approach has often been termed' Positivist ' ; it might equally well be

1 Cf. Carnap, Del' Logische Aufba.u der Welt,p. 245 fl .Frank, " Das Kausalgesetz un d seine Grenze n ", Schr. z. wiss. Weltauff., Vol. VI, Vienna,1932, p. 270 fl .94


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alternatively, as assumed in present dayPhysics, determine the probability ofcertain value distributions of parameters(statistical laws of Quantum Mechanics).In contrast to the universality ofPhysics cases arise in every partial language which can be expressed in thatlanguage but are fundamentally incapableof explanation in that language alone,e.g. in Psychology e.g. a psychologicalwhere no explana- event such as a pertory law can be ception can beformulated of a described but notstatement of the explained; for suchkind "Mr. A is now an event is conseeing a red circle " ditioned not onlysince the explana- by other mentaltion must deduce events but also bythis statement from physical (physiostatements such as logical) events." A red sphere islying before Mr. A"and "Mr. A has hiseyes open ", etc.

The prediction of an unknown is similarto the explanation of a known truth orevent , viz. derivation with the help of laws.Hence sub- or partial languages are not sufficient for prediction and a unitary language

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