GREGOR SCHIEMANN THE LOSS OF WORLD IN THE IMAGE: ORIGIN AND DEVELOPMENT OF THE CONCEPT OF IMAGE IN THE THOUGHT OF HERMANN VON HELMHOL TZ AND HEINRICH HERTZl In searching for the origins of current conceptions of science in the history of physics, one encounters a remarkable phenomenon. A typical view today is that theoretical knowledge-claims have only relativized validity. Historically, however, this thesis was supported by proponents of a conception of nature that today is far from typical, a mechanistic conception within which natural phenomena were to be explained by the action of mechanically moved matter. Two of these proponents, Hermann von Helmholtz and his pupil Heinrich Hertz, contributed significantly to the modernization of the conception of science. Paradigmatic for their common contribution to this development is the way in which they employed the concept of image. By considering the origin and the different meanings of this concept we may trace a line of development which begins with Helmholtz's original claim that a universally and forever valid theory provides a unique representation of nature. It continues with the realization that the status of scientific knowledge is capable of revision; and it arrives at Hertz's admission that a variety of theories over a domain of objects is possible, at least at times.2 I. PICTORIAL ASPECTS OF THE SIGN ELEMENTS OF HELMHOLTZ'S CONCEPTION OF SCIENCE UNTIL ABOUT 1870 Throughout his li1'e Helmholtz stood for an empiristic conception 01' science. That meant that science should derive its knowledge by the generalization of specific experience through the method 01' induction. On this basis Heimholtz began in the 1860s to characterize the laws known through natural science by the concept of image [BildP Before then, Heimholtz had trusted that scientific theories could do much more than merely provide an image of the world. According to his early scientific and popular !ectures, theoretical natural science did not merely comprehend empirical lawful regularities, but also discovered the substantial causes of the appearances, which are, according to Heimholtz, completely detennined mechanically (1889, 4f.; 1882,2:608L 1903a, l:40f. and 45). The concept of the image always implies a separation of the represented from the representation.4 On Helmholtz's early views, however, scientific theories penetrate their objects, so to speak, exploring their inner structure. Like probes they yield glimpses of hitherto unseen worlds, and they are therefore true in the objective sense (1889,7: 1903a, 1:41). 25 D. Baird et al. (eds.), Heinrich Hertz: Classical Physicist, Modern Philosopher, 25-38. © 1998 Kluwer Academic Publishers. Printed in Great Britain. 26 GREGOR SCHIEMANN Helmholtz initially placed this objectivity in strict opposition to the merely subjective testimony of sensory perception in the life-world; this perception does not have any immediate access to reality but consists in the psychological processing of sensations. The peculiarity of the sensations is detennined by the constitution of the sense organs. Their specific mann er of excitation is triggered only by external stimuli. Because the sensations do not bear any resemblance to these stimuli. he labeled them and the perceptions which they trigger '"signs" or also "symbols" (1882.2:608; 1903a. l:4lff.).5 By using the expression "sign." Helmholtz points to a particular analogy: he compares the sensations with the characters of written script. In doing so he suggests that the internal sensations resemble the extemal world as little as. for instance. the name of a person resembles the person itself (1882. 2:608 et passim). But the analogy has its limits. While a name can designate various persons or objects. the signs of sensation satisfy a one-to-one correspondence. which I will call sign-constancy: to one sign of sensation should always correspond at most one thing (1882. 2:608; cf. 1903a. 1:41ff,),6 The contrast between the sign-character of perceptions and a scientific cognition of reality is founded on Heimholtz' s understanding of causality. According to hirn scientific statements have the same causal structure as the real happenings in nature. In contrast, the psychological process producing the sensory perceptions is irreducibly determined by acausal elements. Heimholtz envisions a changeable. open-ended learning process that is not free of errors (e.g .. hallucinations). In it, an autonomous subject steps into the relationship between sign and signified in a constitutive manner, creating what may be called a triadic relation. Whether a sign has been understood correctly can be judged only in relation to its successful application. Therefore the subject needs to be accorded a certain scope of action which Heimholtz equates with freedom of the will (1903a, 1:114: 1856. 427ff. and 797f.). In contrast to Kant, Helmholtz supposes that those phenomena determined by freedom of the will cannot be completely explained causally (1882, 1: 13).7 Sensory perception can therefore become an object of science only partially, to the extent that it agrees with the law of causality. Thus, in order to penetrate into reality science must probe, in each individual case, whether what the senses declare to be similar or different is in fact similar or different (1903a. 1:40). The sensations that are expressed in script fail to contain objective truth whenever they fai! to be causally connected. With the introduction of the concept of the image. HelmhoItz signals adeparture from his critical view of the truth-content of signs of sensation. In 1856, in the first edition of his Handbook oj Physiological Optics. he partially suspends his previous strict opposition of objective and subjective knowledge in order to ground the truthclaims of scientific statements. Going beyond the afore-mentioned sign-constancy. he now postulates the temporal congruence of sign and signified in a theory of perception: The only relation in which there can be real agreement between our perceptions and reality is the temporal sequencc of events with its various peculiarities. Simultaneity, succession. the regular recurrence of simultaneity and succession can happen in our sensations jmt as weil as in the events. (1856, -+-+5) THE LOSS OF WORLD IN THE IMAGE 27 In addition to sign-constancy, a second non-causal congruence of sign and signified is herewith established. While the first concerns the relation of sign to object. the latter relates the temporal structure of the signs to that of the object's properties. Through this congruence in temporal sequence, the signs change their character significantly. They break the scientific monopoly on truth and can give information about "the true essence of things," as Helmholtz says now (1856,446). In order to denote the sign's more inclusive relation to reality. HeImholtz speaks for the first time in his Handbook about "images": Thus the repre,entations of the extemal world are images of thc lawlike succession of natural events. (1856. '++6) Helmholtz here uses the concept of image in the sense of a strict representation [Abbild]. The temporal constitution of the presupposed causal structure of the world is reproduced without distortion in sensory perception. Originating in the theory of perception, this concept of the image soon serves to provide a new determination of the task of science. The object of science is now to "discover and combine into a law" the temporal structure wh ich is inserted into perception (l903a, I :319f.). Scientific know ledge. insofar as it consists in statements of causal law, becomes the pure presentation of the pictorial component of sensory perception. From now on Helmholtz will emphasize that natural laws have the character of a representation of "natural phenomena ... with respect to succession in time" (l903a, 1:395; cf. 1903a, 2:222f. and 358: 1885,586). As science's relation to reality becomes restricted to the perceptible, science loses its unrestricted access to reality. Because laws can only picture the non-intuitive and mathematical relations between properties of objects. natural science can no Ion ger claim to reach the objects themselves, the substantial reasons for the phenomena. While he uses the expression "sign" throughout for a characterization of sensory perception and sensation, Helmholtz's use of the concept of the image ftuctuates. Most of the time he interprets it in the sense just elucidated, namely as strict representation, but occasionally also in the sense of a sign.8 When he tries in some passages of his public speeches to illustrate the relation between sign and image by drawing on the example of the arts, one has the impression that he places the concept of image in a third, more comprehensive meaning above the concept of sign.Y In this interpretation, the concept of image is akin to the concept of a work of art. It has a content which extends beyond the relationship of equality or similarity. and this content belongs only to the image but not to its object. It is subject to all kinds of intentional shaping and is therefore meaningless for science. 2. SlGN-ASPECTS OF THE IMAGE ELEMENTS OF HELMHOL TZ' S CONCEPTION OF SClENCE AFTER ABOUT 1870 Until roughly the end of the sixties Helmholtz endeavoured to justify the truthclaim of scientific knowledge. During the seventies, there occurs a change in the development of Helmholtz's philosophy of science which points in a completely 28 GREGOR SCHIEMANN different direction: on the basis of his theory of perception he begins to relativize the claim to validity which hitherto he had held absolute. The conceptual distinction between sign and strict representation becomes less and less marked. The truth-conditions for signs, which always depend on some success of an action, begin to hold more and more for the scientifically established representations of reality as weil. The psychological processes determining the creation of signs become elementary conditions of cognition which in principle can no longer be transcended by scientific cognition. The possible background and motives for this profound change are various; Heimholtz never explicitly addressed them. Among the most important ones, I wish to mention these: Heimholtz followed a general trend in the natural sciences during the second half of the nineteenth century towards an increasing hypothesization of scientific propositions; this change of his conception of science is related to a crisis of his mechanistic conception of nature, which was to have been a representation of the first causes of nature; and finally this change must be understood as part of the extension of his theory of perception towards a comprehensive theory of knowledge. 1o In his second speech of 1892 about Goethe's scientific work, Helmholtz found the "final result" of his epistemology summarized in the sentence by Goethe, "All things transitory are only symbols [Gleichnis]." To this Heimholtz adds: That is, what occurs in time and what we perceive through the senses, we know only in symbols. hardly know a more pregnant way to express the final result of our physiological theory of knowledge. [ ... ] All knowledge of the laws of nature is inductive, and no induction is ever totally comp1ete. We feel l ... ] our inability to penetrate further [into nature] as a kind of anxiety. (1903a, 2:358) The nature of "transitory things" is still considered to consist in their temporal causal structure; this is represented in perception, the sign-character of which Helmholtz here refers to as "symbol" [Gleichnis]. Until roughly the end of the sixties, Helmholtz assumed that this structure is expressed in the experimentally and inductively established laws of nature and that it can be entirely reduced to mechanicallaws. But now it is no longer possible to complete this reduction if the process of induction cannot be completed, i.e., if there is a remnant of the true causal structure or its representation in perception which eludes science. The content of perception is now richer than the laws known by science, which always remains incomplete in regard to reality. But the knowledge of laws neither changes its causal structure nor its formal mode of presentation (1882, 2:640ff., 3:176). What are subjected to change are its conditions of validity. The relationship of representation can be assumed only as an idealized relationship and can be ascertained only approximately (l903a, 2:243, 393, and 183f.; 1882,2:642). When comparing Helmholtz's concept of image with that of Hertz, it is important to realize that Heimholtz expands his original conception of signs, which is rooted in a theory of perception, into a naturalistic theory of knowledge. This process finds its most pointed expression in a new determination of thought, which Helmholtz had originally viewed as a high court of cognition that would ensure THE LOSS OF WORLD IN THE IMAGE 29 agreement with reality.lI But already towards the end of the seventies he was convinced that in principle thinking is not free of the sign-character. ... rwith this psychological processing of cognition] we are obviously dealing with an elernentary process that lies at the bottorn of all really so-cal1ed even if the critical review anel completion of the pankular steps rnay be missing here. a critical und cornpletion thaI enlers the scientitic formation of concepts and deductions. \ 1903a. 2:233) Now all that the scientilic formation of concepts and logical deductions from statements of law can accomplish is already predetermined in "every particular step" by the psychology of perception. Under these conditions, no autonomy free of experience adheres to thought (which will be Hertz's point of departure). Thought cannot be an independent court for validity but is part of the domain 01' an empirical scienee which ean only approximate the ideal of truthP The aspeets discussed so far eoncern that side of the representation that is inserted into sensory pereeption and that can be presented as law. However, the mode of existence 01' the represented, of eausally structured reality, also beeame increasingly questionable for Heimholtz. Weil into the seventies he had made the realistic assumption 01' a reality independent of cognition. In a eentral passage 01' his 1878 speech "The Facts of Perception," however. Heimholtz relativizes his realism. He reeognizes idealism as an equal and irrefutable epistemologieal alternative and refers to both realism and idealism as "metaphysieal hypotheses" (l903a, 2:2380. Briefly, the change in the determination 01' representation and represented is that Helmholtz becomes inereasingly uncertain about the supposed congruence between them. The scientil1c representation of the world loses its indubitable reference to the world and diminishes in permanence and sharpness. One can also consider this as the outcome of a subordination of thought to the conditions of relating to experience, a relationship to which Heimholtz, in contrast to his early conception of scienee. now accords only approximative validity. 3. L\1AGE-MULTIPLICITY OF SIGNS HERTZ'S PHILOSOPHY OF SCJENCE IN THE PRINCIPLES OF MECHANICS (1894 ) Just like Heimholtz, Hertz uses the concept of image to point to the only agreements that can exist between the external world and one of its representations. Prom sign-constaney and from the simultaneity of sign and signified Helmholtz had derived the claim that all scientific knowledge of laws has the character of a representation. In Hertz's philosophy 01' scienee there is also talk of representations. To hirn, scientific theories are "images" which merely satisfy a "first fundamental requirement" (PM 2) in relation to the external world: in the "neeessary eonsequellts 01' the images in thoughC they can agree with the "necessary eonsequents in nature of the things pictured" (PM 1 ).13 30 GREGOR SCHIEMANN Hertz does not give any cdterion for the representation of objects, however, besides the congruence of "consequents." He restricts the relation between the presentation and the presented to the predictions which can be deduced from a theory and tested by experience. Neither the content of a theory, nor its principles. concepts and laws, but only 1t5 results can still be linked to the external world. Contrary to HelmhoItz, Hertz did not advocate an inductivist conception of science. but a deductivist one. This additional step towards a loss of truth in theoretical cognition is reflected in the change of meaning of the concept of "image." In contrast to Heimholtz, whose representations concerned merely the temporal structure of reality. Hertz' s concept of image postulates elements of theory which have no cognizable connectioll to what they present and which for Heimholtz would have merely been "signs" or "symbols:' To one reality, which Hertz, too, conceives realistically, can now correspond a multiplicity 01' theories. The world seems remote and the concept 01' representation inappropriate. If Hertz uses it anyway, this expresses his hope that the gap between presentation and what is presented may only be transitory, and his hope that the surmised mechanical cause of all phenomena can yet be found. Closer scrutiny reveals how this mechanistic objective, which he shares with Heimholtz, infiuences the determination of his concept of image. It also reveals how this shared objective does not prec1ude a modemization of the cOllcept of science that goes further than Helmholtz*s. In an article on the seventieth birthday of Heimholtz, Hertz mentions as a third "title to fame" besides the invention of the ophthalmoscope and the discovery of the Principle of the Conservation of Force, Helmholtz's work on the physiology of the senses, and emphasizes "how c10sely these investigations are connected with the possibility and legitimacy of all natural knowledge" (Mise 336f.). Although he never explicitly refers to Helmholtz's theory 01' signs or to his concept 01' image, it can be assumed that Hertz was aware of both and recognized their significance for philosophy of science. Tellingly, Hertz goes on in his article to present Helmholtz's theory of perception in a manner best suited to it5 early stage of development. He believes that he finds support in Heimholtz for his own view of sensory sensation as a passive mediator between two entirely separate worlds. He does not at all consider the psychological mechanism involved in the processing of sensations as that elementary process of which Helmholtz later said that it "lies at the bottom of all really socalled thinking."'4 In his article. Hertz poses rather schematically the following question: Is the manitold 01' these relations [mental conceptions formed by the visual sense] sufficiellt to portray all con-:eivable manifolds of the extemal world. to jw'tify all manifolds of the internal world? (Mise 336) Three years later Hertz provides the answer in the Principles 0/ Mechanics, the introduction to which can be considered his contribution 10 the philosophy of THE LOSS OF WORLD IN THE IMAGE 31 science. There he says that a "llniverse conformable to law" cannot simply resllit from perceptions that are triggered by sensations (PM 25). This already contains both the essential contrast with Helmholtz's conception of representation and the point of origin for Hertz's mllitiplicity of images. While the mind may recognize certain reglllarities in perception, it cannot derive from them a complex of laws that encompasses the external world. Hertz relates this to representations in the lifeworld which proceed from immediate sensory perceptions, and he relates it equally to scientific knowledge. In their relation to the world, both life-world representaüon and scientific knowledge satisfy only the "first fundamental requirement." Only their necessary conseqllents correspond with nature. Therefore, Hertz designates both as "images."l) Scientific knowledge differs from representations in the life-world only in that science reqllires possible criteria for the evaluation of images to be formlliated cxplicitly.16 The difference bctween the two had al ready been continually diminished by Heimholtz. It now appears to be only a matter of degree. This impression is strengthened by the fact that one does not find in Hertz a distinction comparable to Helmholtz's persistently upheld division between and representation. In Hertz's work, the word "sign" generally represents the views, expressions and connections that are contained in images, be they images of the Iife-world or of science (PM 7, §297). But it wOllld be amistake to aSSllme that Hertz eqllates, in their pictorial aspect, scientific theories and representations in the life-world. A first, though hardly perspicuous due is provided by Hertz himself when his first mention of the llnrestricted possibility of representing one object by means of "various IS made only in regard to representations in the life-world (PM 2, §297). Why does this possibility exist and to what extent does it obtain in seience too? Hertz first addresses the former question: representations are "not yet llniquely determined" by the agreement of conseqllents necessary in thought and conseqllents necessary in nature (PM 2). The supposition of an alltonomOllS mental capaeity (shared by all humans) i5 implieitly involved here. This capacity need not stand in any relationship to real objects or to its properties. It does not, by self-imposed prescriptions deprive itself of multifariolls possibilities of representation. This supposition wOllld have been unthinkable within Helmholtz's later conception of science. Can Hertz's supposed freedom of mind unfold in science'? Or does it face restrietions which ultimately lead back to Helmholtz's injunction to create a uniqllely valid theory'? The three famous criteria and their eillcidations llsed by Hertz to evaluate the images of science embody the encoded answer to these questions. While the first two criteria, which I wish to call liberal-rational, permit a multiplicity of images, the third estabhshes a rather conservative order among the possible images of a domain of objects. The first criterion of "permissibility" formulates a minimal condition on the form of images: images may not "implicitly contradict the laws of our thought [and] shall be logically permissible" (PM 2), Hertz accords greatest significance to this criterion (PM 33f.). However, he is rather reluctant to specify more precisely what 32 GREGOR SCHIEMANN he means by "laws of thought." He basically rests content with the broad statement that "the nature of our mind" can be decided upon "with validity for all time" (PM 3). Whatever these properties might be, once recognized Of established they are equally valid for all images. Not only do Hertz's remarks on the further determinations of the laws of thought remain vague overall, but they are also not free of contradictions, thus violating the criterion itself. For example, one can learn from the introduction and the main body 01' the Principles of Mechanics that he wishes to prescribe more than the laws of proposition al logic to constrain the freedom of mind in science. In the first part of the main body he claims that he develops his groundwork of mechanics (his "image" of mechanics) exclusively by means of propositions that are "Cl priori judgements in Kanfs sense" (PM § I). However, he adheres to this statement only with his introduction of the concept of time. As soon as he comes to the concept of space, he no longer cares about the difference between synthetic and analytic judgementsP Even when unsatisfied, the claim to a transcendental philosophy yields the necessity that images that fai! to satisfy Kanfs conditions of the possibility of experience are impermissible. But it seems that Hertz considers the apriori character of an image rather as a peculiarity of that particular image.18 This is all the more strange since he applies the criterion of permissibility also to the totality of the multiplicity of images: In order that an image of certain external thing~ may [ ... ) be permissible, not only must its characteristics be consistent amongst themselve'i, but they must not contradict the characteristics of other images already established in our knowledge. (PM 22f.) If one disregards his perhaps merely verbal commitment to a justification of science along the lines of transcendental philosophy, what remains as the most important minimal condition on the form of the images is the demand for freedom from contradictions . The certainty that those sequences of thought at a remove from the world can be in contact with nature at all may be called the Platonic element of Hertz's conception of science.19 The second criterion shows now that this contact must be highly constrained and that ample scope therefore remains for theories in spite of the logic prescribed to them. The second criterion of "correctness" imposes a minimal constraint on the content of permissible images: We shall denote as incorrect any pernlissible images, if their essential relations contradict the relations of external things, i.e. if they do not satisfy our first fundamental requirement. (PM 2) This criterion restricts the agreement of consequents necessary in thought and consequents necessary in nature (hfirst fundamental requirement") to "essential relations." "Essentia)" in this context are exactly those successions which. for whatever reason, claim to be empirically verifiable. For correctness is "perfect," he says, when: all those characterislics of our and correctly correspond to them. which claim 10 represent observable relations of things, do really 9) TRE LOSS OF WORLD IN TRE IMAGE 33 But this perfection need not be permanent. Much more radically than HeImholtz, Hertz assurnes that all empirical knowledge is capable of revision. According to Relmholtz's later conception of science, empirical statements served as an only approximately valid but yet increasingly better confirmed basis of validity for theoretical knowledge (Helmholtz 1903a, 2:22, 186,233). In contrast, Hertz remarks: that which derives from experience can again be annulIed by experience. (pM 9) In contrast to its permissibility, the correctness of a theory cannot be decided "for all time." Thus the agreement of consequents necessary in thought and consequents necessary in nature is deprived of any absolute claim to validity. It i8 questionable in this context why Hertz also considers incorrect theories (as weil as incorrect representations) as images. Why should they be images, if they stand in contradiction to the world? In contrast to Wittgenstein's conception, their logical structure is by no means in itself an image of the world. Since images do not consist of essential relations only, they can be idle and lead to consequents "superfiuous or empty" (PM 2).20 In spite of this description Hertz does not believe it i8 possible to do without them. Though he includes them among those elements of the image which one "can arbitrarily add or take away." he considers them as an inescapable consequence of the mental origin and character of images (PM 3). The image of mechanics that Hertz presents as his own serves as the best example that the choice of which statements should be released for empirical verification and which should not is to some degree arbitrary. For the purpose of a mechanistic explanation of the inanimate world, he introduces a new type of inert mass, and postulates that one of its properties is to be unobservable (PM 25f.).21 In stressing in this and other passages that those "hidden" [verborgen] masses are invisible only to the naked eye, Hertz leaves open the possibility of verifying their properties indirectly through physical measurement. Some of these properties are solid connections [starre Verbindungen] between masses wh ich provide for constant distance and for "approximately ... invariable relative accelerations between the masses" (PM 41). At the end of his introduction he writes: "Now, if we could perceive natural motions with sufficient accuracy, we should at once know whether in them thc relative accelerations ... are only approximately invariable" (PM 41). Here Hertz even speaks of a "decisive battle" [Entscheidungskampf], which has to be "fough! out" [ausgefochten] against other thinkable explanatiolls like those which do not assume hidden masses (PM 41). First of all Hertz assumed hidden masses only for the purpose of explanation. But if it were possible to verify these hidden masses empirically then, as matters stand, the respective theoretical statements would attaill the character of necessary consequents. In this respect, however, Hertz expressed reservations. His remarks did not in principle exclude the possibility that hidden masses could be thc subject of experience.22 Nonetheless, the preoccupation with hidden masses which continued in physics for some time after Hertz died was govemed by the continuing 34 GREGOR SCHIEMÃN hope that further clues to the nature of these masses might be obtained through a more precise examination of electrodynamic phenomena. in particular those relating to the so-called ether.c3 The criterion is thus primarily directed against incorrect relations that are contained in theories and cannot be eonverted by definition into inessential ones.2~ One can see that the criterion does not introduce a serious restriction on the multiplicity of theories. It is rather an encouragement to shield statements which disagree with experience from an empirieal test. Had Hertz left it at these first two eriteria. he would have closely anticipated a currently widespread liberal attitude towards philosophical evaluation of scientific theories. The charaeteristic feature of merely permissible and correct images is that none of them can claim to come eloser to it5 objects than any other. They are equivalent representations of objects. If the domain of objects encompasses all of reality. orif you will the truth, and if the only access to this reality consists in equivalem presentations. then the concept of the image itself comes to an end. together with the realistic conception of a reality that exists independently of images. It no longer makes sense to talk about a relation if one of its two components. namely the extemal wor1d, has completely collapsed into the other. The fuH significance of the far-reaching change introduced with Hertz's third criterion of "appropriateness" becomes dear only against the background of this scenario. With this criterion Hertz drasticaHy restricts the conditions under which multiple theories become possible. He subordinates them to a process of adaptation and seJection which maximizes the predictive scope and empirical content of theories. The multiplicity of theories is considered not as a permanent state but as a state of beginning or transition, in a development which is directed at the minimization of equivalent presentations. Along with HelmhoItz. Hertz assumes that this development approximates the goal of a (mechanical) theory which alone is valid in its time. Hertz uses '"distinctness" to refer to the maximization of predictive scope: Of two relations of the same object that is the more appropriate which pictures more of the essential object. the one which we may call the more distincL (PM 2) As long as other objects are disregarded, it is characteristic for Hertz's concept of object that it corresponds rather weIl to a consilience of a variety of predictions all related to olle object within a single It corresponds rather less weil to the occurrence of such predictions across various images. This theoretical call for unification holds not only for special domains of objects in natural science, but for the totality of natural phenomena in generaL at least in the inanimate world: We sbould remember that r when discussing appropriateness I we are considering the whole range of present physical knowledge. (P~1 10)25 But while the mind has to strive towards a unified image of nature, it can bring one about in a variety of ways. That is why it is possible to start from different sets THE LOSS OF WORLD IN THE IMAGE 35 of principles in the derivation of predictions. Beyond this, any number of "inessential" or "empty" statements are permitted. The maximization of empirical content is directed against this last rest of a superftuous content of images. Hertz refers to this criterion as "simplicity": Of two images of equal distinctness the more appropriale is the one whieh contains. in addition 10 the essential characteristics. thc smal Icr number of superfluous or empty relations, the simpler of the Iwo. (pM 2) Hertz is convinced that in the course of time we can "finally succeed in obtaining the most appropriate" images (PM 3). If this formulation already suggests the substitution of the multiplicity of images by a single image of reality, this is indeed what Hertz considered possible. About his own proposal for an image of mechanics he says: Whelher the presenlation here given 10 Ihis problem is the only possible one, or whether Ihere are other and perhaps better possible ones, remains 10 be seen. (PM xviii) For Hertz, it is certain that the most appropriate i1' it is possible at all, can only be a mechanical one. The highly complicated image proposed by hirnself would become significantly simpler if it turned out that all empty consequents proved to be essential. Implicitly, he assurnes an agreement between his image and a mechanical structure hidden behind the phenomena. The criterion of appropriateness restriets the multiplicity of permissible and correct images to such an extent that it relieves them of their relativized equal standing. But this criterion also leaves the images that remain as a kind of knowledge that is capable of revision and that may, if only for a whde, grasp in a simpler manner a world that is forever separated from mind. 4. CONCLUSION Compared to HeImholtz, Hertz departed more clearly from the aim of a complete (mechanistic) explanation of nature, which is still recognized by both as the ideal of cognition. While HeImholtz excluded as a matter of principle the justified coexistence of several theories over a domain of phenomena, the whole objective of Hertz's philosophy of science i8 precisely to justify this coexistence, at least for the current state of inquiry. In regard to reality, which both had postulated in a realist manner, there occurred a far-reaching loss of tmth that began with HeImholtz and continued with Hertz's philosophy of science. Initially, theories were not images 01' thc world, because they themselves invaded their objects and thus came into possession of the truth. With the introduction of the concept of image, scientific theories become distant from the world: they are merely represemations of a lawful structurc, of the causal relations between real objects. (Heimholtz is much closer to Wittgenstein's later image-theory of meaning than is Hertz,) What appeared to Helmholtz as an obvious 36 GREGOR SCHIEMANN consequence of this knowledge (the prediction of future phenomena) becomes for Hertz the remnant of what truth natural science can know about the world. The structure of this knowledge need no longer be determinate, as it was for Heimholtz; different images of a domain of phenomena, which can include the whole (inanimate) world, are now possible and can mutually relativize their validity. If one takes as a benchmark, not the tradition preceding both physicists, but the subsequent development of the conception of science, Helmholtz appears, roughly speaking, to stand closer to the present in one respect. He proposes much more forcefully than Hertz the now broadly accepted removal of the distinction between apriori presupposed laws of thought and those empirical propositions that are capable of revision. With hirn, thinking loses its function of safeguarding assertions and becomes subject to the uncertain conditions of experience. Against this loss of validity, Heimholtz places a non-negotiable set of assumptions concerning reality which will legitimate the representational character of laws. With Hertz the situation is inverted. While he acknowledges no absolute support in reality for claims to validity, he takes the laws of pure thought, though no longer sharply determined, to be absolutely valid, and he sees in them a unified point of reference that effectively limits the multiplicity of images. These tendencies towards relativitized claims to validity, which face and complement each other in the relationship between Helmholtz and Hertz, are united in the subsequent development of the philosophy of science. Just as thought could no longer be kept distinct from experience, so it proved impossible to secure experience independently of arbitrarily fixed theoretical presuppositions. By focusing on the concept of image, I have addressed an aspect of Helmholtz's and Hertz's thought which, though it is of great importance for their respective philosophies of science, is only of limited significance for their work as a whole. The fact that, in terms of their respective claims of validity of scientific knowledge, Helmholtz and Hertz both appear to be in a single line of development, is due to their congenial approach. How elose they were would be more apparent if one considered the relationships that existed between their respective philosophies of science and specific work in their fields of interest.26 (The fact for example, that Hertz could directly refer to Helmholtz's work with his concept ofhidden masses.) But the philosophy of science has to go beyond the results of specific scientific inquiries and be understandable without reference to their respective contexts. The contrasts between the two scientists are revealed by the independent uses they made of the concept of image within their philosophies of science. There are basic differences between Helmholtz's inductivist and Hertz's deductivist conception of science, between the multiplicity of theories excluded by Helmholtz and pemlitted by Hertz, between the content of the reality referred to by mechanical principles and laws of nature on Helmholtz's account and the emptiness of the reality referred to by scientific theories on Hertz's, and finally between Helmholtz's view that experience is capable of producing knowledge and Hertz's insistence that experience can annull it. Institut für Philosophie, Humboldt Universität zu Berlin, Berlin, Germany THE LOSS OF WORLD iN THE IMAGE 37 KOTES I would Hke to thank Alexander Goroncy und Alfred Nordmann for translating my text. e The und first development of this eoncep! is predominuntly documented by several lectun'~s in which Heimholtz talks about the tasks and methods of science (1889 and 1903a. including the lecture about Goethe's seience). also in both editions of his Handbook 0/ Physiological Optics (1856 and 1885). Hertz presented his view of the concept of in the famous introduction to his Principles 0/ Mechanics. For a comparison betwecn Helmholtz's and Hertz's concept of image see Majer 1985. 3 For Helmholtz's conception of seienee see Cahan 1993b and Schiemann 1997, Chap. B.n.3 and Chap.B.III. In Helmholtz's view induction is a method of inferring generallaws from particular experienee. It is the foundation for the discovery and the justification of naturallaws (cf. 1903a, 1:169ff.. 2:338ff.: 1856, 447f.). " For the concept of image in German philosophy in the 19th century see Schlüter. D. and W. Hogrebe, "Bild," in J. Ritter and K. Gründer (eds.). Historisches Wörterbuch der Philosophie (Darmstadt: Wissenschaftliche Buchgesellschaft, 1971). 5 Fm Helmholtz's theory of pereeption, in whieh he develops the eoneept of sign see Hatfield 1990, Steven Turner, In the Eye '5 Mind: Vision and Ehe Helmholtz-Hering Controversy (Prineeton: University Press, 1994). Theo C. Meyering, Historical ROOfS 0/ Cognitive Science (Dordrecht: Kluwer, 1989). and Schiemann 1997. Chap.B.l1 Ja. 6 I take the expression sign-constancy from Meijering op. eit. (note 5). Among the~e he includes wirh certainty the phenomena of the human and weial seiences (1903a, I: 171), with reservations he includes so me phenomena of the inanimate world (1856,454), and to a eertain degree he finally includes sensual perceptions. Helmholtz's understanding of eausality reflects an empiricist position that is basically different from Kant's idealistic position. R In the sense of representation: 1856,446: 1903a, 2:222 ("For of the image one demands some sort of similarity wirh the depieted objeet") and 358. In the sense of sign: 1903,2:222 ("Images of the things delivered to us by the senses"): 1885, 590 and 599 ("the totality of perspeetival images"), Q "An image must be similar in so me respect to an object. A stalue, for example, has the same bodily form as the human being after whieh it is modeled: a painting has the same color and perspective projection. For a sign, it is suffieient that it appear whenever that which it signifies makes an appearance, the correspondence between Ihem being restrieted to their appearing simultaneously." (l903a, 1 :393: similarly, though without mentioning simultaneity, in 1903a. 2:222) W Changes in Helmholtz's eonception of seienee have often been discussed, see e.g. Benno Erdmann, Die philosophischen Grundlagen von Hermann von HeImholt::;' Wahmehmungstheorie (Berlin: Abhandlungen der Preussischen Akademie, philosophischhistorische Klasse, 1921); Hörz and Wollgast 1971: König 1968: Buchwald 1994b; Gary Hatfield. "HeImholtz and Classicism: The Seience of Aesthetics and the Aestheties of Science" in Cahan 1933a, pp. 552-558: Heidelbcrger 1994: and Schiemann 1994 and 1977, Part B. For the increasing hypothesization 01' scientific. propositions in the nineteenth eentury. see Diemer 1968, and Herbert Schnädelbach. Philosophie in Deutschland 1831-1933 (Frankfurt: Suhrkamp. 1983). 11 Helmholtz's view of thought as a high court is expressed not only by his position on causality but also by his views on logie and mathematics in Heimholtz 1903a, I: 175f. 12 Helmholtz al ready believed in 1868 that his work on the physiology of the senses had intervened for the first time '"into the hitherto inaeeessible field of mental processes" (1903a, 1 :268). D For Hcrtz's concept of image, see D'Agostino 1990. and Majer 1985. 1-\ Cf. pp. 28f. 15 Hertz also speaks of "symbols" and, in agreement with his realism. about "virtual" or "seeming [ScheinbilderJ" (PM I). 16 As apart of this. the descriptions used in the and their possible referenee to experienee need to be rendered distinct (PM 2f.). I) "The space [ .. ] is therefore the space of Euelid's geometry, with all the properties which this geometry ascribes to it. It is immaterial to us whether these properties are regarded as being given by the laws of our internal intuition, or as consequenees of thought which necessarily follow from arbitrary definitions." (PM §2). 38 GREGOR SCHIEMANN IR Nowhere in his very detailed critiques of the other images of mechanics does he mention that they do not satisfy the principles oftranscendental philosophy (PM 4ff.). 19 This interpretation is directed the supposition that Kantian philosophy played an important role in Hertz's thinking. See. for example. Kuczera 1983, 0' Agostino 1990. Hacker 1986. Cf. note 7. 20 Hertz applies the term 'hypotheses' to these "inessential" relations (PM 25f.). 21 Therefore, this is an inessential re.lation (ef. PM 39f.) 22 Hertz's uncertainty on the epistemo.logical status of hidden masses is stressed by 0' Agostino .I 990, p. 60. 23 For Hertz's ether theory and its infiuence in German physics, see Breunig 1988 and Grigorjan and Polak 1964. 2~ A theory would thus be ineorreet if one of its statements did not agree with the Principle of Conservation of Energy, but eould stiH be related to eXlperlelllce. 2, For the restriction to the inanimate. see PM 38. 26 Cf. Mulligan 1987. Buchwald 1 994a. and D'Agostino 1971.