CHAPTER 1Re onsidering Friedman and the A Priori1.1 INTRODUCTIONMi hael Friedman's book Dynami s of Reason published 2001 an and shouldalready be regarded as a lassi within the tradition of s ienti� philoso-phy. Friedman's aim in the book is to ombat what he onsiders to betwo major dilemmas of our ontemporary philosophi al situation, the nat-uralisti predi ament in the �gure of Quinean epistomologi al holism andpost-Kuhnian on eptual relativism most prominently attributed to the Ed-ingburgh S hool of Barnes and Bloor. The �rst move of Friedman's atta k isto fa e the naturalisti hallenge by arti ulating a on eption of dynami aland relativized a priori onstitutive prin iples within mathemati al natu-ral s ien e. His se ond move is attempting to develop a notion of univer-sal, trans-histori al s ienti� rationality in response to so iologi al on ep-tual relativism. Quite original and surprising is not merely the sele tion ofphilosophers whose advi e Friedman is seeking but also the way Friedmansynthesizes the various answers of the philosophers questioned into a promis-ing neo-Kantian strategy to he kmate Quinean epistemologi al naturalismas well as so iologi al on eptual relativism.1.2 FRIEDMAN'S NEO-KANTIAN PROJECT1.2.1 Challenging NaturalismWhat Friedman �nds most wanting in Quine's holisti on eption of s ienti� knowledge as a vast web of inter onne ted beliefs upon whi h sensory inputsimpinge only along the periphery is that it portrays the totality of di�erentparts of our system of knowledge � s ienti� dis iplines su h as mathemat-i s, physi s, and geography � as fun tioning symmetri ally in relation tothe adjoining sensory experien e. For Quine the web of beliefs is thus nota strati�ed system but rather a �at holisti stru ture whose distinguishedparts equally fa e �the tribunal of sensory experien e� (Quine; 1951, p. 38)in the fa e of �re al itrant experien e� in su h a manner that absolutely �nostatement is immune to revision� (Quine; 1951, p. 40):[T℄otal s ien e is like a �eld of for e whose boundary onditionsare experien e. A on�i t with experien e at the periphery o a-sions readjustments in the interior of the �eld [ . . . ℄ But the total1

2 Re onsidering Friedman and the A Priori�eld is so undetermined by its boundary onditions, experien e,that there is mu h latitude of hoi e as to what statements to re-evaluate in the light of any single ontrary experien e. [ . . . ℄ Anystatement an be held true ome what may, if we make drasti enough adjustments elsewhere in the system. [ . . . ℄ Conversely,by the same token, no statement is immune to revision. Revi-sion even of the logi al law of the ex luded middle has been pro-posed as a means of simplifying quantum me hani s; and whatdi�eren e is there in prin iple between su h a shift and the shiftwhereby Kepler superseded Ptolemy, or Einstein Newton, or Dar-win Aristotle? (Quine; 1951, pp. 39-40)Friedman's point of departure for riti izing this radi al anti-apriorist on- eption of knowledge is pre isely by vehemently denying that this supposedlys ienti� ally oriented version of anti-apriorism gains any truth or even plau-sibility from the histori al development of mathemati al natural s ien e fromPtolemy via Kepler and Newton to Einstein. On the ontrary, from Fried-man's perspe tive, the Quinean �gure is not supported by the revolutionary hanges within mathemati al physi s but rather strikingly obvious under-mined and dis on�rmed. To rea h this on lusion, Friedman draws upon re-sour es from a quite surprising dire tion in the form of the logi al-empiri isttradition represented by the early writings of Rei henba h and Carnap. Thereason why this should ome as a surprise is at least twofold. Firstly, thistradition has ordinarily been regarded as starkly opposed to neo-Kantian on eptions of thought and, se ondly, it a tually forms the riti ized foil onwhi h Quine begins to ere t his own position in the now famous arti le TwoDogmas of Empiri ism (1951) (from whi h I ited above) and by whi h he,a ording to the standard telling of the story, simultaneously sealed the ex-e ution of the logi al-empiri ist tradition ultimately arried out in Kuhn'sbook Stru ture of S ienti� Revolutions (1962) eleven years later. But, thesimpli� ations and drawba ks of this a ount of the history and the downfallof logi al empiri ism, �rmly implanted and inherited in the Quinean natu-ralisti tradition, have been pointed out within the last two de ades by aswarm of histori ally oriented philosophers like Alberto Co�a, Alan Ri hard-son, Don Howard and Robert DiSalle to name a few next to Friedman himselfwhose revisionist work on the history and signi� an e of logi al empiri ism olle ted in Re onsidering Logi al Positivism (1999) onstitutes the most im-

1.2 Friedman's Neo-Kantian Proje t 3portant ba kdrop for his own systemati version of s ienti� philosophy under onsideration.1.2.2 Rei henba h and the Relativized A PrioriFrom Friedman's perspe tive, the important moral of these histori al studiesis, on the one hand, that the philosophi al outlook of early Rei henba h aswell as early Carnap was so profoundly shaped by Kantian trans endentalphilosophy that they did not just reje t Kant's on eption of the syntheti apriori on the spot in the light of Sir Arthur Eddington's experimental on�r-mation of the phenomenon of light bending in 1919 predi ted by Einstein'sgeneral relativity theory due to its appli ation of a non-Eu lidean spa e-time stru ture. But, on the other hand, ontrary to the response from the amp of Kantian orthodoxy to Einstein's theory and Eddington's �ndings,the two s ienti� ally edu ated philosophers did neither outright dismiss rel-ativity theory from a supposedly higher philosophi al vantage point. Whatthey did instead was trying to develop a new, but still unambiguous Kantian,notion of a priori prin iples that simultaneously paid areful attention to therevolutionary developments in mathemati s and mathemati al physi s sin eKant. The learest version of this new logi ist-empiri ist on eption of thea priori, a ording to Friedman's telling, was arti ulated by Rei henba h inhis �rst book The Theory of Relativity and A Priori Knowledge publishedin 1920. Rei henba h's �rst insight thereby is to distinguish two di�erentmeanings of Kant's on eption of the syntheti a priori (Rei henba h; 1965,p. 48):1. ne essarily true or true for all times2. onstituting the on ept of obje tHis next and, at the same time, de isive step is then to argue that the pro-found lesson we have to learn from the theory of relativity is that we must ommit the former meaning to the �ames while maintaining the latter. Inother words, Rei henba h argues in onsonan e with Kant that every phys-i al theory ne essarily omprises a priori onstitutive prin iples groundingthe empiri al meaningfulness of its mathemati ally formulated laws. Theunderlying idea is that s ienti� (that is, genuine obje tive) knowledge mustbe formulated or framed in mathemati al formalism. However, for this to be

4 Re onsidering Friedman and the A Prioripossible in the �st pla e, oordinating prin iples are ne essary whose fun -tion is to set up an assignment between the pure mathemati s and on reteempiri al phenomena in su h a way that the laws gain de�nite empiri almeaning. Hen e, we have to distinguish between onstitutive oordinatingprin iples (`axioms of oordination') and properly empiri al laws (`axioms of onne tion'). Nevertheless, Rei henba h goes beyond Kant in laiming thatthese oordinating prin iples hange and develop during transitions fromone theory to its su essor. Hen e, we have to abandon Kant's believe in anabsolutely �xed sto k of onstitutive a priori prin iples by advan ing to a on eption of relativized and dynami al onstitutive (and in this very sensestill) a priori prin iples. Friedman's fundamental laim, to whi h we turnnow, is that this early logi ist-empiri ist on eption of the a priori gives amu h more a urate and vivid a ount of the histori al dynami al evolutionof mathemati al natural s ien e than Quine's anti-apriorism admits.1.2.3 Newtonian ConstitutivityFriedman thus sets himself the task of developing Rei henba h's analysis ofthe onstitutive a priori further by spelling out in more detail than the latterhad done how this on eption should be applied in the e�ort to elu idatethe stru ture of Newtonian, spe ial relativisti as well as general relativisti spa etime theory. The ru ial question in this onne tion is whi h part of therespe tive theory Friedman identi�es as ful�lling the onstitutive fun tion of oordination. In relation to Newtonian spa etime he noti es at the outsetthat Newton himself distinguished three parts in his theory:1. a al ulus of in�nitesimals for on eptualizing in�nite limiting pro esses2. on epts of for e and matter determined in the three laws of motion3. the law of universal gravitationIt's a matter of histori al fa t that Newton developed ea h of the three om-ponents � mathemati s, me hani s, and gravitational physi s � in order togive a uni�ed theory of terrestrial and elestial motion. But, Friedman arguesin the dire tion of Quine, this by itself does not mean or imply that the threeparts fun tion symmetri ally in the overall onjun tion. The laimed asym-metries ome to the fore, a ording to Friedman, when we take a loser lookat the mutual relationships between the three omponents. For instan e, to

1.2 Friedman's Neo-Kantian Proje t 5begin with the relationship between the mathemati al part and the me han-i al part, Newton's se ond law of motion states that the (impressed) for e Fon a body equals the body's (inertial) mass m times its a eleration a, wherethe a eleration is de�ned as the double derivative x = d2x/dt2(= dv/dt)of the body's position x. In other words, this me hani al law annot evenbe formulated without the in�nitesimal al ulus and, for this very reason,it is fundamentally mistaken to view the two parts as ful�lling symmetri- al fun tions in relation to the total theory. We should rather understandthe mathemati al part as supplying �elements of the language or on ep-tual framework, we might say, within whi h the rest of the theory is thenformulated� (Friedman; 2001, p. 36).For Friedman, a similar asymmetri al relationship holds between me han-i s and gravitational physi s. The gravitational part in Newton's theory isen apsulated in the law of universal gravitation that states the existen e ofa (gravitational) for e of attra tion between any two bodies in the universewhose magnitude is dire tly proportional to the produ t of the two massesand inversely proportional to the square of the distan e between them. Fried-man noti es that for this law to be empiri ally well-de�ned, we need to knowin relation to whi h referen e frame the a elerations in question are de�ned.In other word, the law presupposes a privileged referen e frame relative towhi h its empiri al meaning is �xed. Su h a frame of referen e is alled aninertial frame and is itself determined as a frame wherein the three laws ofmotion hold. Hen e, Friedman on ludes, �without the Newtonian laws ofme hani s the law of universal gravitation would not even make empiri alsense, let alone give a orre t a ount of the empiri al phenomena� (Fried-man; 2001, p. 36). Another way of spelling out the asymmetry between thegravitational law and its me hani al ounterparts would be noti ing that, ontrary to the universal law of gravitation, the onjun tion of me hani allaws does not laim the existen e of any parti ular kind of for e (next to grav-itational or ele tro-magneti al). For example, the se ond law only says thatif a body is a ted upon by an (impressed) for e, then this for e is related tothe mass of the body in the parti ular way pres ribed by the law. The threelaws together thus rather fun tion as a kind of onstitution of on epts likefor e and a eleration �guring in empiri al laws su h as the law of univer-sal gravitation. In other words, for Friedman these laws are themselves notproperly empiri al laws, but rather the kind of a priori onstitutive prin ipleshe was looking at.

6 Re onsidering Friedman and the A Priori1.2.4 General Relativisti ConstitutivitySo mu h for Newtonian physi s. Friedman goes on to argue that an analo-gous a ount and lari� ation of the role of onstitutive a priori prin iplesholds for the theory of general relativity. In parti ular, this theory equally onsists of an asymmetri al tripartite stru ture omprising pure mathemat-i s, onstitutive a priori oordinating prin iples and properly empiri al laws.The ru ial di�eren e between the theories from Friedman's perspe tive is, of ourse, that the onstitutive framework omprising pure mathemati al om-ponents and a priori oordinating prin iples has essentially hanged in thehistori al development leading from the Newtonian prede essor to its rev-olutionary Einsteinian su essor. For instan e, while Newtonian physi s isen apsulated in Eu lidean geometry and the in�nitesimal al ulus, the the-ory of general relativity is framed in the non-Eu lidean geometry developedby Bernhard Riemann in his generalized theory of manifolds. This revolu-tionary new mathemati s employs the on ept of a variably urved spa etimegeometry whi h ould not even be formulated at the time of Newton and, onsequently, whi h ould not play any onstitutive role within Newtonianphysi s. For this very reason, the Newtonian oordinating prin iples annotful�l a similar onstitutive fun tion in relation to this revolutionary new kindof pure geometry. Enabling the appli ation of Riemann's new ideas withingeneral relativity theory therefore implies the repla ement of Newton's lawsof motion with a new form of oordination. What Einstein ame up with wasthe prin iple of equivalen e whi h identi�es the traje tories of bodies a�e tedonly by gravitation as geodesi s (straightest possible paths) in the variably urved spa etime geometry. The variable urvature itself, a ording to Ein-stein's theory, is determined by the gravitational �eld equations as a fun tionof the mass-energy distribution in the universe. Friedman explains the rela-tionship between the prin iple of equivalen e and the �eld equations furtherby pointing out that without the former the latter would have no empiri almeaning at all. Be ause, without the prin iple we had not singled out someempiri al phenomena as ounterparts of the mathemati al on epts deter-mined by the equations � in this ase the notion of geodesi : �The prin ipleof equivalen e does pre isely this, however, and without this prin iple theintri ate spa etime geometry des ribed by Einstein's �eld equations wouldnot even be empiri ally false, but rather an empty mathemati al formalismwith no empiri al appli ation at all� (Friedman; 2001, p. 38). Again, Fried-

1.3 Logi al Spa e and Empiri al Spa e 7man on ludes, the three parts omprising general relativity theory fun tionasymmetri ally in the sense that the �rst two parts fun tion as the onsti-tutive framework of the third, and hen e only properly empiri al, part. Theoverall on lusion we should draw from the development of mathemati alnatural s ien e sin e the hey days of Newton thus fundamentally ontradi tsQuinean epistemologi al holism:In periods of deep on eptual revolution it is pre isely these on-stitutively a priori prin iples whi h are themselves subje t to hange � under intense pressure, no doubt, from new empiri al�ndings and espe ially anomalies. [ . . . ℄ [But t℄he idea of ne -essary presuppositions onstituting the onditions of possibilityof the properly empiri al parts of a s ienti� theory is not un-dermined [on the basis of these revolutionary developments℄ butrather on�rmed! (Friedman; 2001, p. 45)1.3 LOGICAL SPACE AND EMPIRICAL SPACEIn order to larify the notion of onstitutivity outlined above Friedman intro-du es a distin tion between the spa e of logi al possibilities, on the one hand,and the spa e of empiri al possibilities, on the other. Friedman begins thedis ussion leading to the introdu tion of the distin tion by pointing out thatthe role of what he designates a priori onstitutive prin iples is to provide�the ne essary framework within whi h the testing of properly empiri al lawsis then possible� (Friedman; 2001, p. 83). Be ause, as we have seen, withoutthe prior a eptan e of a onstitutive framework the properly empiri al lawshave not been assigned to any on rete empiri al phenomena and, for thisvery reason, they still belong to the sphere of abstra t mathemati s. Forinstan e, ounting Eddington's mentioned experimental test of the phenom-ena of light bending in the vi inity of heavy bodies like the sun predi ted byEinstein on the basis of al ulations arried out within his general theory asempiri al eviden e for the theory presupposes the a priori a eptan e of the onstitutive framework of this very theory.Hen e, Friedman argues, we an and should distinguish two very di�er-ent on eptions of empiri al theory testing depending on whether we evaluatethe experiment from an internal or external perspe tive; in our ase from theinternal perspe tive of an Einsteinian physi ist or the external perspe tiveof a Newtonian. The point Friedman is trying to bring home is that both

8 Re onsidering Friedman and the A Prioriphysi ists will agree that Einstein's theory yields more a urate predi tions,that is, from a purely pragmati or instrumental on eption of theory testingthey agree. However, ontrary to the Einsteinian, the Newtonian an onlya ept this al ulation as a kind of bla k box predi tion, be ause from thelatter's point of view �the onstitutive framework of general relativity is noteven possible or oherent, and there is thus no sense in whi h Einstein's �eldequations an a tually be empiri ally true� (Friedman; 2001, p. 84). Hen e,on Friedman's a ount the internal perspe tive fa ilitates a on eption of em-piri al theory testing thi ker than a purely instrumental a ount in the sensethat the former (but not the latter) allows for the notion of genuine empiri- al eviden e within the ontext of an already a epted framework. In otherwords, a onstitutive framework de�nes what Friedman designates a spa e ofempiri al possibilities that fun tions as the ba kground against whi h exper-iments are then able to determine whi h empiri al possibilities are a tuallythe ase. In addition, Friedman introdu es the notion of the spa e of logi alpossibilities given by the purely mathemati al part of a onstitutive frame-work. For instan e, �[w℄ithout the Riemannian theory of manifolds, we mightsay, the spa e-time stru ture of general relativity is not even logi ally possi-ble, and so, a fortiori, it is empiri ally impossible as well� (Friedman; 2001,p. 84). The di�eren e between these two notions is that logi al possibilityis supposed to be a ne essary but not su� ient presupposition of empiri alpossibility, that is, the latter is �rst de�ned when the logi al possibilities un-der onsideration are su essfully oordinated with some on rete empiri alphenomena. Thus, a ording to Friedman, it is pre isely the onstitutive or oordinating prin iples that in the end de�ne what he alls real as opposedto merely logi al possibility. So what the distin tion brings to the fore is�rst of all the lari� ation that the spa e of logi al possibilities of our on-stitutive framework is independent of its spa e of empiri al possibilities: theformer is presupposed by the latter. For instan e, it is possible to hold thatthe empiri al possibility of general relativity is in omprehensible and at thesame time on�rm the omprehensibility of Riemann's theory of manifolds onstituting the logi al spa e of general relativisti possibilities.1.3.1 Constitutive Prin iples as Ne essary, Non-empiri al PresuppositionsIn the beginning of the se ond part of his book Friedman tries to explainfurther �what exa tly it means for (putatively) a priori prin iples to be ne -

1.3 Logi al Spa e and Empiri al Spa e 9essary onditions of empiri al knowledge� (Friedman; 2001, p. 73). The�rst thing he noti es is that to say that A is a onstitutive ondition of Bmeans, in more standard terminology, that A is a presupposition of B. Inother words, �A is a ne essary ondition, not simply of the truth of B, but ofB's meaningfulness or possession of a truth value� (Friedman; 2001, p. 73).Within the framework of Newtonian physi s, for instan e, we only know howto apply the universal law of gravitation by presupposing the truth of thelaws of motion: the former has empiri al ontent only relative to an inertialframe de�ned as a referen e frame in whi h the laws of motion hold. Fried-man then remarks, however, that the idea of a presupposition by itself inno way su� es to demar ate the Kantian notion of ne essary ondition he istrying to revitalize:Yet the mere idea of a presupposition in this sense is of oursemu h too weak to apture the Kantian notion we are after [ . . . ℄We want to reserve this hara terization for parti ularly funda-mental presuppositions lying at the basis of mathemati al physi s� prin iples whi h, a ordingly, an plausibly be taken as fun-damental presuppositions of all empiri al truth (at least in thenatural s ien es) (Friedman; 2001, p. 74).Without posing su h an extra requirement, Friedman noti es, every presup-position would automati ally ount as a onstitutive prin iple on his a ount.But, the latter emphasizes, sin e this is ertainly not what he intends heneeds to add a restri tion. Admittedly, his hara terization of onstitutiveprin iples as �prin iples whi h [ . . . ℄ an plausibly be taken as fundamentalpresuppositions of all empiri al truth� does help to grasp the Kantian notionhe is hinting at. The question remains, however, whether it really does helpto larify matters. What reasons do we have to adhere to the existen e ofsu h fundamental prin iples? In parti ular, what does it mean to re ognizewhether it is plausible that a prin iple is presupposed by at least all naturals ienti� knowledge? If a prin iple is supposed to be a ne essary onditionof natural s ienti� knowledge should its status as su h not be more thanplausible to us?Although Friedman does not really address this issue at fa e value, hisdis ussion of the laws of motion indi ates without doubt that he takes the lat-ter to be ne essarily presupposed by not only the universal law of gravitationbut all empiri al knowledge obtainable within the framework of Newtonian

10 Re onsidering Friedman and the A Prioriphysi s. Be ause, within the ontext of Newtonian physi s, they de�ne theunambiguous spatio-temporal arena of all empiri al laws:[A℄s we now understand it, these laws of motion de�ne a privileged lass of relative spa es or referen e frames (what we now allinertial frames) in whi h the modern on epts of spa e, time, andmotion then unambiguously apply [ . . . ℄ The Newtonian laws ofmotion are thus presuppositions of the properly empiri al lawsof Newtonian physi s (su h as the law of gravitation) (Friedman;2001, pp. 76-77).In so far as other ontemporary bran hes of natural s ien e su h as hemistryand geology did apply standard methods for the measurement of time andpla e, we may add, it is reasonable to say that they were presupposing thelaws of motion, too. Hen e, as DiSalle would put it, on Friedman's a ountthe Newtonian laws of motion empiri ally de�ne on epts of spa e, time,and motion that every natural s ien e of the day applied at least impli itly.Furthermore, as will be ome important later, his a ount of the ne essity of onstitutive prin iples implies that, for instan e, only the Newtonian lawsof motion enable us to empiri ally de�ne the spatio-temporal framework ofNewtonian physi s. If this was not the ase, it is hard to see how theselaws an fun tion as ne essary presuppositions of properly empiri al lawsin Friedman's sense. In other words, the universal law of gravitation itselfmay only presuppose that the Newtonian spa e-time stru ture is somehowempiri ally well-de�ned. But, on the fa e of Friedman's a ount, the latter an only be so by means of the Newtonian laws of motion.This brings us to Friedman's �nal hara teristi of onstitutive prin i-ples: sin e their sole fun tion is to oordinate or mediate between abstra tmathemati al formalism, on the one side, and on rete empiri al phenomena,on the other, they are themselves ategorized as belonging to a spe ial lassof non-empiri al physi al prin iples. Friedman begins to argue his ase bynoti ing that the famous experiments performed by Mi helson and Morleyseem to provide a dire t empiri al test of the so- alled light prin iple whi hstates that the velo ity of light is the same in any inertial frame indepen-dently of the velo ity of the light sour e, and whi h, on Friedman's a ount, omprises a onstitutive prin iple in the ontext of spe ial relativity theory:The famous interferometer experiments of Mi helson and Morley(1882, 1887), for example, whi h result in no dete table in�uen e

1.3 Logi al Spa e and Empiri al Spa e 11of the motion of the earth on the velo ity of light, seem to supplyas good an empiri al test as an be imagined for the invarian eof the velo ity of light in di�erent inertial frames and thus forthe light prin iple as it is �rst introdu ed in the spe ial theory ofrelativity (Friedman; 2001, p. 86).But, despite appearan e, Friedman goes on to argue that the null result ofthe experiments annot be on eived as a ru ial experiment in favor of therelativisti light prin iple, even though the prin iple would be empiri allyuntenable, if the experiment had not had this result. In other words, he doesstress that a onstitutive prin iple �must always have a ounterpart in reality,and, if su h a ounterpart does not exist, the prin iple is empiri ally va uousand thus useless.21 The ru ial question, however, is whether su h a prin iple an thereby be ome empiri ally false� (Friedman 2001, p. 87). For instan e,the empiri al ounterpart of the onstitutive framework of Newtonian physi s orresponds to the existen e of an inertial frame in whi h the laws of motionhold to a high degree of approximation. Friedman himself wants to drivethe on lusion home that su h prin iples annot be empiri ally tested in thesame way as properly empiri al laws. In the ase of the light prin iple, forexample, he argues that the out ome of the Mi helson-Morley experimentsonly shows that we annot dete t any e�e t on the behavior of light due tothe motion of the earth with respe t to the ether. Hen e, the experimentdoes leave other alternatives open than the spe ial relativisti interpretationof the null result as due to the empiri al fa t that the velo ity of light isinvariant in all inertial frames. What Friedman is driving at is, of ourse, thehistori al ir umstan e that Lorentz among others in orporated the resultof the Mi helson-Morley experiments within the Newtonian spatio-temporalframework. Hen e, on Friedman's a ount, this is the reason why we annotview the experiment as a genuine empiri al test of spe ial relativity withrespe t to its alternatives.To larify this matter, Friedman attempts to spell out more learly whathe sees as the fundamental di�eren e between Lorentz's ele trodynami altheory and Einstein's spe ial theory of relativity by ontrasting the hoi ebetween the two with ases of empiri al underdetermination. Contrary tothe later ases, he emphasizes, the two alternatives of the former ase dopre isely not have a onstitutive framework in ommon:Whereas Lorentz and Fitzgerald take an essentially lassi al ba k-

12 Re onsidering Friedman and the A Prioriground stru ture for spa e, time, and motion to be already suf-� iently well de�ned and only subsequently lo ate the new em-piri al dis overy in question [the null result℄ as a pe uliar (butadditional) empiri al fa t formulated against the ba kground ofthis lassi al stru ture, Einstein alls the whole lassi al stru tureinto question and uses the very same empiri al dis overy empiri- ally to de�ne a new fundamental framework for spa e, time, andmotion entirely independent of the lassi al ba kground (Fried-man; 2001, p. 88).As we have seen, the empiri al ounterpart of the lassi al ba kground stru -ture amounts to the existen e of a set of inertial frames de�ned as referen eframes in whi h the laws of motion hold. In other words, rather than prop-erly empiri al laws the latter are onstitutive prin iples or empiri al riteriathat any referen e frame has to satisfy in order to ount as an inertial frame.What Lorentz did in this light, a ording to Friedman's point of view, was topresuppose that the set-up for the Mi helson-Morley experiments was at restrelative to an already su� iently well de�ned inertial frame in the Newtoniansense. More pre isely, Lorentz argued that the rest frame of the laboratory ofMi helson and Morley approximated a lassi al inertial frame during periodsof time where the a eleration of the laboratory frame (due to the rotationof the earth) ould be negle ted. The measured onstan y of the velo ity oflight relative to the motion of the set-up with respe t to the alleged ether isthen explained by means of for es that are supposed to ontra t the arms ofthe interferometer in the dire tion of the relative motion in question. Hen e,what Lorentz does is to introdu e a new dynami al e�e t, whi h then groundsa distin tion between e�e tive and real oordinates: only the latter state fa tsabout reality in a dire t manner, whereas the former have to be orre tedfor the said dynami al e�e t. This is done by transforming the e�e tive o-ordinates of the laboratory frame into the equivalent real oordinates of theether frame by means of the orresponding Lorentz transformation.Einstein, on the ontrary, uses �his light prin iple empiri ally to de�nea fundamentally new notion of simultaneity and, as a onsequen e, funda-mentally new metri al stru tures for both spa e and time (more pre isely,for spa e-time)� (Friedman; 2001, p. 88). In other words, what Einsteindoes is to de�ne a new notion of inertial frame in whi h the Newtonian se -ond and third laws of motion have been repla ed by the light prin iple as

1.3 Logi al Spa e and Empiri al Spa e 13 onstitutive ondition. Thus, from Friedman's point of view, the null resultof the Mi helson-Morley experiments is not happily viewed as an empiri- al dis overy within an already well de�ned spatio-temporal framework, butrather shows that the rest frame of the laboratory in question satis�es thenew onstitutive ondition, whi h is to say that this rest frame orrespondsto an inertial frame in the spe ial relativisti sense. As Friedman remarks,writers in�uen ed by Poin aré express this shifting epistemologi al fun tionof the light prin iple by saying �that Einstein has `elevated' an empiri al lawto the status of a onvention � or, as I myself would prefer to put it, tothe status of a oordinating or onstitutive prin iple� (Friedman; 2001, p.88). This way of putting it makes good sense, a ording to Friedman, inso far as �[i℄t is pre isely here that an essentially non-empiri al element of`de ision' must intervene, for what is at issue, above all, is giving a radi allynew spa e-time stru ture a determinate empiri al meaning � without whi hit is not even empiri ally false but simply unde�ned� (Friedman; 2001, p.88). Seen in this light, the de ision to de�ne the notion of an inertial frameby means of the light prin iple does not at all hinge upon the null result ofthe Mi helson-Morley experiments. As Friedman emphasizes, this in agree-ment with Einstein's own explanation that this experimental out ome didnot play any prominent part in his development of spe ial relativity theory.Trying to de�ne a parti ular spatio-temporal stru ture empiri ally by hoos-ing a de�nite set of oordinating prin iples hen e makes perfe tly sense, eventhough we may not have any previous knowledge, whether the hosen set ofprin iples will turn out to have any inertial frame as empiri al ounterpart.But, although Friedman here draws attention to what he sees as the on-ventional hara ter of oordinating a parti ular mathemati al stru ture toempiri al phenomena, he simultaneously emphasizes that he ertainly doesnot mean that we do not have empiri al motivations for preferring one oor-dination to another. About the ase under onsideration he writes:Indeed, the new empiri al dis overy in question � undete tabil-ity of di�eren es in inertial motion in ele trodynami s � providesus with strong empiri al motivation, not only for entertaining anew oordination, but also (as Einstein was apparently also the�rst to see) for doubting the adequa y of the lassi al oordina-tion. For, if there were in fa t an empiri al ounterpart to the lassi al notion of absolute simultaneity, then there would be (in

14 Re onsidering Friedman and the A Priorithe ontext of ele trodynami s) an empiri al ounterpart to ab-solute velo ity as well. But the new empiri al dis overy stronglysuggests that there is no su h empiri al ounterpart [ . . . ℄ The lassi al spatio-temporal stru ture, whi h we had assumed in the ontext of Newtonian physi s to be unproblemati ally empiri allywell de�ned, thereby turns out to be empiri ally meaningless.23Here we ertainly have an empiri al motivation, and a parti ularstrong one, for preferring the new empiri al oordination e�e tedby Einstein (Friedman 2001, pp. 88-89).What Friedman seems to argue is that the out ome of the Mi helson-Morleyexperiments gives us parti ularly strong reasons to doubt not only that thelaboratory frame orresponds to a Newtonian inertial frame but the veryexisten e of su h frames altogether. For, sin e the laws of Maxwellian ele -trodynami s are Lorentz- ovariant, in the ontext of Newtonian physi s theywere only supposed to hold true in a frame at rest relative to the ether,whi h in turn would make �absolute velo ity� empiri ally well de�ned. Aswe have seen, instead of doubting the adequa y of the lassi al oordination,Lorentz explained the surprising null result by introdu ing a new dynami ale�e t whi h was meant to explain the null result by legitimizing a distin -tion between e�e tive and real oordinates: measurements arried out withmeasuring instruments in motion relative to the ether would have to be or-re ted for the dynami al distortion that all bodies in luding the instrumentsthemselves would be subje ted to. What I am referring to is, of ourse, the ontra tion of the lengths of bodies in the dire tion of motion with respe t tothe ether as well as the retardation of lo ks moving relative to the ether. Theresult of all this was, for example, that if two events were measured to o ursimultaneously with respe t to the ether frame, while they were measuredto o ur after one another in an inertial frame moving relative to the ether,only the former would ount as informing us about when the two eventsreally had happened (in relation to one another). The later measurementwould just give us an apparent result, whi h then had to be orre ted bymeans of the orresponding Lorentz transformation to yield the real result.In other words, only empiri al measurements arried out in the ether framewould result in real or absolute quantities. In all other ases the measur-ing results themselves would just be apparent. Hen e, on Lorentz's a ount,absolute simultaneity does not amount to the invarian e of the simultaneity

1.3 Logi al Spa e and Empiri al Spa e 15relation with respe t to e�e tive measurements arried out in inertial framesanymore. It rather orresponds to the hara terization of one system � theether frame � as absolute, even though it turns out that we do not haveany empiri al means for distinguishing this frame from all the others. Thus,on Friedman's a ount, this should be at least some kind of empiri al moti-vation �for preferring the new empiri al oordination e�e ted by Einstein,�although the latter immediately reminds us about the ir umstan e that �thissituation is not happily likened to more standard ases of empiri al under-determination, where two empiri ally equivalent hypotheses fa e o� againstthe ba kground of a ommon onstitutive framework, and methodologi alprin iples su h as simpli ity or onservativeness are then invoked to settlethe question� (Friedman; 2001, p. 89).In this se tion I tried to bring to the fore that Friedman is beginningto walk on a very �ne line: he wants to �ght o� naturalism by developinga notion of relativized a priori onstitutive prin iples, but without thereby ommitting himself to one or another version of on eptual relativism. The�rst lear indi ation of Friedman's balan ing a t is his introdu tion of adistin tion between empiri al eviden e of the �rst order or dire t empiri aleviden e, on the one hand, and empiri al eviden e of the se ond order orempiri al motivation, on the other. Instan es of the former are formulatedagainst the ba kground of a onstitutive framework in whi h the spa e of log-i al possibilities has been given an empiri ally well de�ned spatio-temporalrealization by means of a set of non-empiri al onstitutive prin iples. Inother words, under onditions that we are able to ontrol in the laboratory,measurements give us empiri al eviden e of the �rst order to as ertain whi hempiri al possibilities happened to be the ase. As noted above, Friedmanhimself hara terizes su h experiments as genuine empiri al tests or empiri- al tests evaluated from the internal perspe tive of a parti ular onstitutiveframework. An empiri al motivation, on the other hand, is not meant toexpress straightforward empiri al eviden e. For, if it did, it would be verydi� ult to see how Friedman ould maintain onstitutive prin iples to benon-empiri al in nature. The way the latter expresses this point is by stress-ing that, at the end of the day, we still have the freedom to de ide whetheror not we want to hange our set of onstitutive prin iples. So it is, stri tlyspeaking, not irrational to keep the old onstitutive framework. But if so, wemay ask, what kind of reason does an empiri al motivation orrespond to?As we will see below, Friedman introdu es the notion of empiri al reason by

16 Re onsidering Friedman and the A Priorilinking it intimately to his a ount of dire t empiri al eviden e. At the out-set, his notion of rationality is therefore an intra-paradigmati notion. Theissue in question thus be omes how Friedman broadens his a ount in orderto en ompass empiri al motivations. How does he explain the dynami aldevelopment of a priori onstitutive prin iples as a rational pro ess?1.3.2 The Road from Constitutivity to RelativismFriedman's point of departure is that this dynami al development has whatwe appropriately ould all a purely logi al side as well as an empiri al side.The former problem is en apsulated in the question of how to pi ture the ex-pansion of the spa e of logi al possibilities. Here, Friedman's favourite exam-ple is again the development from Eu lidean geometry to Riemann's theoryof manifolds en losing the former as a spe ial ase of possible manifolds. Thelatter problem is the question of how to make sense of the development of apriori oordinating prin iples onstituting the spa e of empiri al possibilities.Friedman addresses these two questions by larifying why and how the prob-lem of hanging a priori prin iples relates to Kuhn's well-known dis ussionof in ommensurability and its so iologi al �avored o�spring of on eptualrelativism. In parti ular, what Friedman points out is that the distin tionbetween instrumental and ommuni ative rationality arti ulated by JürgenHabermas applies to the situation under onsideration in the sense that it o-in ides with the distin tion between an instrumental on eption of empiri altheory testing and Friedman's own internal on eption of testing:Standards of ommuni ative rationality are given by what I [ . . . ℄ all an empiri al spa e of possibilities or spa e of reasons, in thatagreement on the onstitutive prin iples de�nitive of su h an em-piri al spa e of possibilities (mathemati al prin iples and oordi-nating prin iples) yields agreement on what an ount as an em-piri al reason or justi� ation for any given empiri al possibility.A shared onstitutive framework thereby fa ilitates shared mutu-ally omprehensible rational argumentation (Friedman; 2001, p.93).The �rst thing Friedman points out in this passage is that to any empiri alspa e of possibilities there belongs 1) a purely mathemati al stru ture on-stituting the internal or formal relationships between any two points in the

1.3 Logi al Spa e and Empiri al Spa e 17spa e and 2) a set of oordinating prin iples onstituting how this stru tureis oordinated to empiri al phenomena that human beings may observe. Forinstan e, we an model the surfa e of the earth as a 2-dimensional mathemat-i al sphere by employing the laws of astronomy as oordinating prin iples. Ifwe a ept this oordination, any sailor well edu ated in the art of navigationwill not only be apable of determining the position of his ship, that is, whi h�earth point� or empiri al possibility it o upies, but he will also be able tojustify rationally why he is ertain that the ship is where he takes it to be.But, of ourse, he annot onvin e a human being whi h believes that theearth is �at or a person who is ignorant of navigation (the latter may never-theless believe the sailor, be ause he happens to know that the sailor passednavigation s hool). In parti ular, the sailor's identi� ation of the ship's po-sition by means of the orre t appli ation of sextant and nauti table only ounts as an empiri al reason or justi� ation for humans that already agreeon the onstitutive prin iples de�nite of our earth model. In other words,only what I alled the internal perspe tive fa ilitates rational argumentation.From an external perspe tive, the sailor's ability to maneuver the ship fromone destination to another an only be evaluated as the expression of somekind of instrumental rationality or pragmati skill. To take another example,the stubbornness of the Newtonian from our example above not to a eptthe Einsteinian onstitutive framework results in his la k of ability to ountEinstein's predi tion of the phenomena of light bending due to al ulationsperformed within the setting of general relativity as more than a bla k boxpredi tion. This is pre isely to say that the Newtonian evaluates ea h andevery appli ation of Einstein's theory as a purely instrumental rational a t.In other words, the Newtonian is unable to understand su h an appli ationas a ommuni ative rational a tivity in the sense that it is grounded or basedon a shared onstitutive framework fa ilitating � onstitutive mutually om-prehensible rational argumentation.� What Friedman takes all this to showis that the shift from one onstitutive framework or paradigm to its su es-sor raises the hallenge of on eptual relativism, be ause �what is rationallya eptable within one paradigm may not be so a ording to the standards[ . . . ℄ of the other� (Friedman; 2001, p. 95).

18 Re onsidering Friedman and the A Priori1.3.3 The Idea of Prospe tive Communi ative RationalityFor Friedman, there is thus a rather obvious sense in whi h Kuhn's idea of in- ommensurability or non-intertranslatability between su essive onstitutiveframeworks in a s ienti� revolution has real signi� an e. Moreover, viewedfrom Friedman's perspe tive, Kuhn's defen e of s ienti� rationality basedon the in rease of solved s ienti� puzzles in ( ases of genuine revolution-ary) transitions from one paradigm to its su essor is seen to be wanting.Be ause, from Friedman's standpoint, Kuhn's own attempt to fa e the rela-tivisti hallenge exposes itself as the expression of a purely instrumental orpragmati on eption of rationality. And, as Friedman has argued, su h ana ount does in an important sense not answer the real problem but ratherpoints to a quite un ontroversial fa t, namely that the stubborn Newtonianalso must ount Einstein's predi tions as a pragmati su ess. Hen e, thedeeper problemati of in ommensurability arti ulated above is left totallyuntou hed:Our problem [ . . . ℄ is to explain how a revolutionary transitionfrom one s ienti� paradigm or onstitutive framework to an-other an be ommuni atively rational, despite the fa t that weare in this ase fa ed with two essentially di�erent and even in- ommensurable `logi al spa es.' [ . . . ℄ How [ . . . ℄ an it ever be( ommuni atively) rational to a ept the later onstitutive frame-work? How, in parti ular, an there ever be empiri al eviden ethat ounts as an empiri al reason, in our sense, in support of thelater framework? (Friedman; 2001, pp. 95-96)For instan e, over oming the threat of on eptual relativism thus involvesarti ulating why Newtonians have good ( ommuni ative) reasons to give uptheir stubbornness and abandon their hitherto preferred onstitutive frame-work for the sake of (one of) the Einsteinian(s). This means, above all, thatthe standard move of pointing to the phenomenon of inter-framework onver-gen e (prominently exempli�ed by the transitions from Newtonian physi sover spe ial relativity to general relativity) as a supposed bulwark againstrelativism is insu� ient, be ause the very idea of su h a onvergen e an onlybe given to someone already looking from the retrospe tive standpoint andthus from the wrong stan e: the onvergen e is shown to obtain by demon-strating how to a quire the old spa e of possibilities as a (approximately)

1.3 Logi al Spa e and Empiri al Spa e 19spe ial ase of the new spa e. What we need is not su h a retrospe tivereformulation of the old onstitutive framework from within the new onebut rather what Friedman alls an explanation from the prospe tive stan e:we have to arti ulate in what sense it an be prospe tively ommuni ativelyrational to shift from the old paradigm to the new one. For instan e, wehave to explain why the stubborn Newtonian also has good ( ommuni ative)reasons to be ome an Einsteinian.Friedman himself begins answering this pre isé of our guiding problem ofarti ulating an a ount of the dynami al development of relativized a priori onstitutive prin iples standing up to the two hallenges of epistemologi alholism and on eptual relativism by dis riminating what he sees as a pro-found retrospe tive di�eren e between what we have alled the logi al sideand the empiri al side of the problemati . His further laim is that thissupposed retrospe tive disanalogy has a dire t prospe tive impa t:Indeed, with respe t to the purely mathemati al part of our on-stitutive frameworks, we have the [ . . . ℄ result that the laterprin iples ontain the earlier prin iples quite exa tly, in that thespa e of possibilities in mathemati s ontinuously (and, as it were,monotoni ally) in reases. [ . . . ℄ In mathemati al physi s, how-ever, the situation is rather more ompli ated. For, in the �rstpla e, we are here dealing with approximate rather than exa t ontainment, and, in the se ond pla e, we must here re kon withreal (or empiri al) as well as logi o-mathemati al possibility. [ . . . ℄As the spa e of real or empiri al possibilities ontinuously (butnot quite monotoni ally) expands, prin iples that ount as on-stitutive at one stage may shift to the status of merely empiri allaws at a later stage. And it is pre isely be ause of this phe-nomenon, I believe, that revolutionary transitions within mathe-mati al natural s ien e give rise to a mu h more serious hallengeof on eptual relativism (Friedman; 2001, pp. 96-97).Friedman begins the passage with the assertion that later mathemati al prin- iples always ontain or onserve the earlier ones quite exa tly, i.e. he laimsthat mathemati ians at a later stage always are able to understand as well asto proof and hen e to justify rationally the results of an earlier stage. Thus,the on eption of (quite) exa t ontainment is learly a retrospe tive notion.Of ourse, the same holds for the on ept of approximate ontainment whi h

20 Re onsidering Friedman and the A PrioriFriedman applies to su essive stages of empiri al possibilities due to the fa tthat prin iples at one stage fun tioning in a onstitutive manner may loosethis fun tion and as a result end up as mere (approximate) empiri al laws.For instan e, a ording to Friedman, this is the ase with the three laws ofmotion in the revolutionary transition from the Newtonian to the general rel-ativisti framework. But, we should ask, why is Friedman justi�ed in givinghis laim a prospe tive impa t?Friedman's own answer just seems to be that the disanalogy betweenphysi s and pure mathemati s �is not simply that the retrospe tive ontain-ment is here [in physi s℄ only approximate. The ru ial point, rather, is thatthe later onstitutive framework employs essentially di�erent onstitutiveprin iples� (Friedman; 2001, p. 98). What he laims is hen e that expandingthe spa e of logi al possibilities does not involve abandoning some of the for-mer prin iples whi h onstitute the old spa e of logi al possibilities. Beforewe pro eed with physi s let me brie�y indi ate why Friedman's point thatmathemati al-physi al prin iples an loose their onstitutive fun tion afterall may similarly apply to pure mathemati s. For example, what we nowa-days designate the natural numbers at one stage in the history of mathemati s onstituted the on ept of number per se, i.e. the spa e of numbers was thesystem of natural numbers. Later in history mathemati ians developed othernumber stru tures su h as the rational, the real and the imaginary numbersand thereby expanded or generalized what new generations of mathemati- ians would learn to identify with the number spa e. Hen e, later generationsstill ounted parti ular natural numbers as instan es of the number on ept.But, of ourse, at su h later stages the system of natural numbers is nothappily viewed as onstituting the (generalized) number spa e. For instan e,the prin iple of natural numbers that every number (n) has a unique su - essor (n + 1) is not true within a number spa e omprising rationals orreals. A similar point holds in relation to the history of geometry. For a longtime Eu lidean geometry was mankind's unique and unambiguous on ept ofgeometry and, for this very reason, Eu lidean geometry in a quite straight-foward sense onstituted the spa e of geometri al possibilities. Sin e then,the situation has hanged rather fundamentally due to the development of(non-Eu lidean) hyperboli and proje tive geometries followed by Riemann'sfurther generalization of the spa e of geometri al possibilities in his theoryof manifolds. Hen e, Eu lid's axioms still determine a parti ular geometri alstru ture but it might make sense to to say that they have lost their onsti-

1.3 Logi al Spa e and Empiri al Spa e 21tutive fun tion in the sense that the Eu lidean idea of geometri al spa e hasbeen repla ed by Riemann's more general notion of manifold. For instan e, ontrary to the Eu lidean on eption, this generalized notion of geometri alspa e fa ilitates (generalized) triangles whose angles do not ne essarily addup to 180o. But, let us not dwell any more on this point simply be ause itappears to be in Friedman's favor rather than to his disadvantage.1So let us look at Friedman's explanation of how it an be ome prospe -tively ommuni atively rational to abandon one spa e of empiri al possibil-ities for another. The �rst thing Friedman noti es is that, sin e we �rst dohave a new standard pro edure of empiri al testing after the transition, theproblem is not to explain why it is rational to ex ept the truth of a properlyempiri al theory su h as Einstein's new theory of gravitation. The problemis, rather, to give an a ount that explains �how Einstein's new theory ofgravitation be omes a rational or reasonable possibility in the �rst pla e �to explain, as it were, how it �rst be ame a live option� (Friedman; 2001,p. 100). He then goes on to dis ern the omparison of s ienti� groupsworking within di�erent onstitutive frameworks to spee h ommunities ofradi ally separate languages as the problemati kernel of Kuhn's a ountof in ommensurability. For, although Friedman himself adheres to the ideaof in ommensurability, he argues that the new onstitutive framework is al-ways formulated as a response to problems and on erns raised within the oldframework. And for this very reason Friedman feels obliged to on lude that�su eeding on eptual frameworks in a s ienti� revolution are more akin todi�erent stages of development within a ommon linguisti or ultural tradi-tion� (Friedman; 2001, p. 100). From this observation it is then only a singlestep to the arti ulation of the idea prospe tive inter-paradigmati rationalityhe is aiming at: the on epts and prin iples of the new onstitutive frameworkdo not only onverge retrospe tively to the on epts and prin iples of the oldframework under ertain boundary onditions, �but they also develop out of,and as a natural ontinuation of, the old on epts and prin iples�(Friedman;2001, 101). So, although pra titioners of the new framework apply on eptsand prin iples with no ounterpart in the old framework, they are neverthe-less able to appeal rationally to the pra titioners of the old framework �usingempiri al and on eptual resour es that are already available at pre isely thisearlier stage� (Friedman; 2001, p. 101).1 Mit paper!

22 Re onsidering Friedman and the A PrioriWith this in mind, Friedman returns to Einstein's introdu tion of the lightprin iple in the spe ial theory of relativity. The �rst thing he now observesis that not only was Einstein's work arti ulated against the ba kdrop of theLorentzian approa h to ele trodynami s whi h tried to a ommodate the nullresult of the Mi helson-Morley experiments within a lassi al spatio-temporalstru ture, but it was also related to the development of the on ept of iner-tial frame in the late nineteenth entury whi h lari�ed the issue of absoluteversus relative motion in Newtonian me hani s. Hen e, when Einstein �tookan already well-established empiri al fa t (the empiri al indistinguishabilityof di�erent inertial frames by opti al and ele trodynami al means) and `ele-vated' it to the status of a onvention or oordinating prin iple� (Friedman;2001, p. 102), he thereby appealed to on eptual resour es and problems thatwere already available. Physi ists working within old framework were there-fore not only able to understand the new oordination, but also prepared tore ognize it as a reasonable live option.The next thing Friedman emphasizes is that, rather than belonging to thes ienti� realm, these resour es and problems are distin tively philosophi alin nature. To bring out, for example, that the long tradition of re�e tionon the question of absolute versus relative motion is largely philosophi ally,we just have �to keep in mind the large amount of unresolved intelle tualdisagreement surrounding it up to the present day� (Friedman; 2001, p. 105).Thus, besides the levels of empiri al laws and onstitutive prin iples, we alsohave to distinguish a third meta-s ienti� level of distin tively philosophi alre�e tions:Here we are on erned with what I want to all meta-paradigmsor meta-frameworks, whi h play an indispensable role in mediat-ing the transmission of ( ommuni ative) rationality a ross revolu-tionary paradigm shifts, despite the fa t that they are in apable,by their very nature, of the same degree of ( ommuni atively) ra-tional onsensus as �rst-level or s ienti� paradigms (Friedman;2001, p. 105).But, as Friedman observes right away, distinguishing between philosophi aland s ienti� re�e tion in this manner leads dire tly into a new di� ulty:if philosophi al re�e tion is di�erentiated from s ienti� re�e tion on thegrounds that the former is in apable of rea hing the same degree of rational onsensus than the latter, how an philosophi al re�e tion ever be of any help

1.3 Logi al Spa e and Empiri al Spa e 23in rea hing a new rational onsensus during s ienti� revolutions? In otherwords, how is it possible that the philosophi al realm itself hara terized byunsettled questions and on erns may fa ilitate the rational agreement thattime is ome to abandon the old onstitutive framework in favor of a radi allynew one?Friedman's answer to this question omprises three steps. Firstly, henoti es that the only thing the required rational onsensus has to a omplishis to make the new framework re ognizable as a possible live option. Se ondly,despite the fa t that distin tively philosophi al debates by their very naturedo not on lude in stable onsensus over obtained results, Friedman arguesthat, nevertheless, the s ienti� parties arguing against ea h other do manageto rea h relatively stable agreement on the important ontributions to thedebate whi h implies that any one of them has to be taken very seriously byany responsible stan e to the ontinuing debate. Finally, he points out thatdistin tively philosophi al re�e tion is able to shake up s ienti� re�e tion insu h a manner that � ontroversial and on eptually problemati philosophi althemes be ome produ tively intertwined with relatively un ontroversial andunproblemati s ienti� a omplishments� so as �to fa ilitate the introdu tionand ommuni ation of a new s ienti� paradigm� (Friedman; 2001, p. 107).Einstein's advent of spe ial relativity theory serves again as one of Fried-man's main examples. A ording to the latter, in the spe ial relativisti ase the �rst of the three point is exhibited by the fa t that Einstein self- ons iously appealed to the traditional debate about absolute versus relativemotion in order to fa ilitate that his introdu tion of a new oordination wouldbe taken seriously as an alternative to the lassi al oordination. Se ondly,although the debate about the reality of absolute motion at the philosophi allevel was hara terized by disagreement, there was nonetheless a relativelystable onsensus that thinkers su h as Newton, Leibniz, Kant, and Ma h hadarti ulated the most important arguments whi h thus any new ontributionto the debate had to address with the outmost seriousity. Thirdly, Friedman ontends that the ontemporary lari� ation of the status of absolute versusrelative motion within Newtonian physi s due to the development of the on- ept of inertial frame by physi ist su h as Carl Gottfried Neumann (188?),Ludwig Lange (188?) as well as Lord William Thomson Kelvin and PeterGuthrie Tait (1896) orresponded to a �relatively un ontroversial and un-problemati s ienti� ontribution to this debate� (Friedman; 2001, p. 107).Moreover, in arti ulating the new oordination, Einstein utilized the newly

24 Re onsidering Friedman and the A Prioridis overed empiri al fa t regarding the velo ity of light in a very surprisingmanner. Friedman therefore feels entitled to on lude that lassi al physi istshad to take Einstein's proposal seriously on their own terms:Sin e Einstein's introdu tion of a radi ally new on eptual frame-work was thus seriously engaged with both the established philo-sophi al or meta-s ienti� tradition of re�e tion on absolute ver-sus relative motion whi h had surrounded lassi al physi s sin eits in eption, and also with already established empiri al and on eptual results at the s ienti� level, a lassi al physi ist,on his own terms, had ample reasons seriously to onsider Ein-stein's work. He did not, of ourse, need to adopt Einstein's newparadigm as orre t, but he would have been irrational, unreason-able, and irresponsible (again on his own terms) to fail to onsiderit as a live alternative (Friedman; 2001, p. 108).1.4 LANGE'S NATURALISTIC CRITIQUE OF FRIEDMANA very penetrating analysis of Friedman's neo-Kantian on eption of rela-tivized a priori prin iples has been given by Mar Lange in his review essayon Dynami s of Reason (Lange; 2004). One of the �rst things Lange noti esis that �Friedman's point [ . . . ℄ that every empiri al predi tion made by New-ton's law of gravitation requires Newton's laws of motion� (Lange; 2004, p.704) does not seem to be on lusive, be ause Friedman �has not argued thatthe parti ular ` oordinating prin iples' of Newtonian me hani s are ne es-sary for Newton's law of gravitation to have any bearing on physi al reality�(Lange; 2004, p. 704). Rather, what the latter has shown is �that with-out something to play the role of Newton's laws of motion, Newton's law ofgravitation is irrelevant to physi al reality� (Lange; 2004, p. 704). I tou hedthis issue above in my dis ussion of Friedman's a ount of the ne essity of onstitutive prin iples. What I did argue was that Friedman's position seemsto imply that only the Newtonian laws of motion enable us to empiri allyde�ne the spatio-temporal arena of Newtonian physi s. Seen in this lightLange's ritique an be stated as the point that it may be the ase that someprin iples are ne essary to empiri ally de�ne the lassi al spa e-time stru -ture, but Friedman has not given us any reasons implying that this an onlybe e�e ted by means of the Newtonian laws of motion. One possible way ofanswering Lange's ritique would be to respond that Friedman's real point

1.4 Lange's Naturalisti Critique of Friedman 25only was to all attention to the ne essity of empiri ally de�ning a parti ularspatio-temporal framework by means of some or another set of onstitutiveprin iples. Lange re ognizes that su h an interpretation may not be om-pletely mistaken, sin e Friedman a tually does express himself ambiguouslywith respe t to this issue. For instan e, he remarks that the standard pro- edure for testing a parti ular empiri al law � ould not even be set up in the�rst pla e without some or another oordinating prin iple already in pla e�(Friedman; 2001, p. 81). But, a ording to Lange, even if we grant Friedmanthat mu h, the latter is still not able to give a satisfa tory a ount of, say,the transition of Maxwellian ele trodynami s from Newtonian to relativisti physi s. Be ause, on his own terms, Friedman has to interpret Maxwell'sequations as hanging their meaning under su h a transition:Unlike Newtonian gravitational theory, however, Maxwellian ele -tromagneti theory survived inta t the shift from Newtonian torelativisti physi s [ . . . ℄ Maxwellian ele tromagneti theory ouldbe interpreted as des ribing the ele tri and magneti �elds asthey appear in a referen e frame at absolute rest (or at leastrelative to the aether). Alternatively, it ould be interpreted asdes ribing the ele tri and magneti �elds as they appear in anyinertial frame. [ . . . ℄ However, sin e Friedman regards the ` oordi-nating prin iples' as onstitutively a priori relative to Maxwelliantheory, he ould not say that we have here one and the same the-ory oupled either with lassi al or relativisti me hani s. Rather,on Friedman's view, there has been a hange in the meaningsof various terms in Maxwell's [ . . . ℄ equations ( f. pp. 98-99)(Lange; 2004, p. 705).The �rst thing Lange points out is that, with respe t to the lassi al spatio-temporal framework, the Maxwellian theory an only be true in one referen eframe.2 This is related to the fa t that the Maxwellian equations are ovari-ant under Lorentz- instead of Galilean transformations. In the ontext ofspe ial relativity, however, the Maxwellian equations an be interpreted tohold in any inertial frame, whi h is due to the fa t that any hange of oor-dinates from one inertial frame to another is now governed by some Lorentz-2 This referen e frame is then interpreted as being at rest relative to the aether.

26 Re onsidering Friedman and the A Prioritransformation.3 Lange �nally argues that, sin e Friedman is maintainingthat properly empiri al laws only have empiri al ontent or truth-value rela-tive to a spatio-temporal framework, hanging the framework of an empiri allaw must imply that at least some of its terms hange their meanings.The reason why Lange does not agree with Friedman on this point is thatthe on eptual foundations of Maxwellian ele tromagneti theory �remainedsomewhat �uid and unsettled until the advent of relativity� and onsequentlyit may �make less sense to speak of Maxwellian theory as undergoing `mean-ing hange' than to speak of the theory as itself highly ambiguous (albeitultimately in a fruitful way)� (Lange; 2004, p. 705). This ambiguity implies,in parti ular, that Maxwellian theory does not presuppose any parti ular setof prin iples empiri ally de�ning frames of referen e in whi h the theory thenapplies, but only some set of su h prin iples. For Lange this means that it be- omes very dubious to ontend that the theory did not survive inta t the shiftfrom Newtonian to relativisti physi s � espe ially be ause Maxwellian ele -tromagneti theory played a pivotal role in the advent of the new relativisti framework. Lange tries to strengthen his argument by noti ing that a similarpoint an also be made regarding Friedman's explanation of the onstitutivefun tion of Newton's laws of motion relative to Newton's laws of gravitation.Contrary to our modern understanding of Newton's laws of motion as im-pli itly de�ning �inertial frames,� Lange remarks that even Friedman himselfrepeatedly observes that Newton did understand them di�erently. The wayNewton did understand his laws of motion whi h Lange is hinting at, we mayadd, was as straightforward empiri al laws de�ned relative to absolute spa e.What this shows, a ording to Lange, is the implausibility of holding thatNewton's law of gravitation does not have any empiri al ontent without anyreferen e frame spe i�ed:Even without any privileged referen e frames being pi ked out,Newton's law of gravitation is not entirely empty of ontent re-garding physi al reality; it might even be taken as asserting thatthere is some set of prin iples for pi king out referen e framesunder whi h it applies with empiri al adequa y. Friedman mighta ept all this and insist merely that without some set of prin- iples, the law of gravitation is empiri ally useless. But again,3 This is of ourse not surprising, sin e Einstein self- ons iously developed the spe ialtheory of relativity to work that way.

1.4 Lange's Naturalisti Critique of Friedman 27without some su h set of for e laws [ . . . ℄, Newton's laws of mo-tion are empiri ally useless. Insofar as all this goes, the situationseems roughly symmetri al (Lange; 2004, p. 707).What Lange here points out is that Friedman may agree that Newton's lawof gravitation only presupposes some or another set of onstitutive prin iples,but nonetheless uphold the distin tion between prin iples and empiri al lawsby ontending that properly empiri al laws will still be empiri ally uselessuntil a parti ular set of su h prin iples has been spe i�ed. Against thisLange argues that we may also regard the prin iples themselves as empiri allyuseless without some for e laws. Lange does not elaborate his ritique anyfurther, but he must have something like the following in mind: without anyknowledge of empiri al for e laws, we will never be in a position to re ognizewhi h frames of referen e a tually happen to be inertial frames. Be ause, ifwe do not know whi h kind of for es exist, then we annot be sure whether wehave properly dis erned all for es in a referen e frames. And as a onsequen ewe annot know whether all for es in a referen e frame o ur in pairs. That is,we are not able to re ognize, if a referen e frames satis�es all three Newtonianlaws of motion. In short, Lange's ritique of Friedman's distin tion between onstitutive prin iples and properly empiri al laws is meant to favor some oranother version of Quinean epistemologi al holism.Having argued his ase for the symmetry between Friedman's empiri allaws and onstitutive prin iples, Lange on ludes his review by giving a on-�i ting interpretation of the philosophi al impa t of the Mi helson-Morleyexperiments. He thereby begins his explanation by questioning Friedman's ontention that although �the undete tability of di�eren es in inertial motion[ . . . ℄ provides us with strong empiri al motivation, not only for entertaininga new oordination, but also [ . . . ℄ for doubting the adequa y of the lassi al oordination,� (Friedman; 2001, p. 88) the hoi e between the two onstitu-tive frameworks �is not happily viewed, in any sense, as a ase of empiri altesting� (Friedman; 2001, p. 89). In parti ular, Lange asks rhetori ally howEinstein's proposal fails to be testable by standard empiri al means, althoughit is able to be motivated empiri ally.As we have seen, Friedman answers this question by arguing that theMi helson-Morley experiments annot be viewed as a genuine empiri al testof Einstein's new oordination, simply be ause Lorentz among others su - essfully arti ulated an ele tromagneti theory of moving bodies whi h in-

28 Re onsidering Friedman and the A Priori orporated the null result within a lassi al spatio-temporal framework. But,although Lange admits that the experiments do not amount to eviden e forspe ial relativity over the Lorentz theory, he ontends that the ir umstan ethat �a lassi al spatio-temporal stru ture an a ommodate these resultsonly by way of some maneuver along the Lorentz-Fitzgerald lines may surelyqualify as some eviden e against that stru ture� (Lange; 2004, p. 709). A - ording to Lange, a very good explanation why the maneuver of Lorentz andFitzgerald is so dissatisfying in hara ter has been arti ulated by Einsteinhimself who questioned that nature has pla ed us in an aether gale only toarrange the laws of nature in pre isely su h a manner that we are unable todete t the gale. In other words, a lassi al spatio-temporal stru ture an onlya ommodate the null result in terms of �an unlikely oin iden e in the lawsof nature, a remarkable ase of `�ne-tuning� ' whi h � ries out to be eliminated� as Einstein does� (Lange; 2004, p. 709). So, even without the existen eof an alternative at hand, we have ample empiri al reasons to be dis ontentwith the Lorentz theory. Lange, of ourse, is well aware that Friedman willbe qui k to respond that this ritique fails to distinguish between �rst-leveland se ond-level s ienti� theories to whi h there orresponds a distin tionbetween �rst-level and se ond-level empiri al reasons. As we have seen, onlythe former amount to genuine empiri al eviden e, whereas the latter nev-ertheless an help to motivate a transition between onstitutive prin iples.Friedman introdu es these distin tions, as Lange ontinues to observe, �on thegrounds that [ . . . ℄ a �rst-level theory's empiri al motivation goes straight-forwardly through se ond-level theory, whereas the se ond-level theory's em-piri al motivation pro eeds only by the gra e of a third-level philosophi almeta-framework and therefore is not happily viewed as a ase of empiri altesting� (Lange; 2004, p. 710). Hen e, Friedman's sharp distin tion between onstitutive prin iples and empiri al laws presupposes a very sharp distin -tion between the s ienti� - onstitutive level and the philosophi al meta-level.But, Lange now argues, pre isely this later distin tion is simply impossible todraw sharply. To make out his ase he remarks that Einstein's own argumentagainst Lorentz relies on onsiderations of unity and parsimony whi h, albeitnot self-explanatory, exa tly belong to the kind of onsiderations that � evenon Friedman's own a ount, we may add � also inform theory- hoi e withina single onstitutive framework. Lange therefore on ludes that Einstein'sargument just seems to provide standard empiri al reasons in favor of thenew framework thus implying that a sharp distin tion between genuine em-

1.4 Lange's Naturalisti Critique of Friedman 29piri al eviden e, on the one hand, and distin tively philosophi al empiri almotivations seems to be unjusti�ed:But I am not sure that there is any point at whi h this deepersear h for adequate resour es suddenly moves out of the s ienti� into the philosophi al realm, or out of `standard' empiri al test-ing into something non-standard. Deeper rises simply demand leverer arguments (Lange; 2004, p. 711).This ends my review of Lange's ritique of Friedman's a ount of relativizeda priori onstitutive prin iples and leads me to the question how to evaluatethe two on�i ting positions. From my perspe tive, Friedman o�ers impor-tant points that throw onsiderable light on the transition from Newtonian torelativisti physi s. However, as we have seen, Lange draws attention to ru- ial ambiguities in Friedman's a ount. For instan e, whether the Newtonianlaws of motion are supposed to omprise the unequivo al set of onstitutiveprin iples for Newtonian physi s or only one among several possible su h sets.Unfortunately, Lange himself does not really formulate any kno k-down ar-guments in favor of his own naturalisti standpoint.Han viser ikke, at man vitterligt kan de�nere inertial frames �symmetrisk�/ på forskellig vis. Derudover meaning shift argumentet voll i die hose, hvisman ser på, at netop DE var grunden til at Einstein var så pissed ... og ikkepga. Mi helson Morley. Det kunne man netop kalde meaning-shift!!! Ikkefordi det er klart, hvordan Lange vil forstå det. Nævn Einstein's indu tiondiskussion gengivet i Zahar! (Det gør Leblond.) Så over til at Leblond hargjort det meget bedre end Lange! => Langt skarpere!!! Både mht. symmetriog mht. hvordan empirisk spørgsmål mht. N og SRT framework!Claus 17.12.2008: Det Lange siger er jo netop, at empiriske lovmæs-sigheder i sig selv har et slags empirisk indhold. De forudsætter nemligbestemt spa e-time! Det et måske meget tæt op ad DiSalle 1995: Spa e-Time. Det er her jeg selv vil hen! Enhver lovmæssighed forudsætter impli iten spa e-time arena. Den største gruppe kan man så kalde dens invariansgruppe eller noget i den stil. Her er DiSalle 2006 måske bedre. Han talerikke om oordinating prin iples eller gør han?Derudover er detWhat I �nd unsatisfa tory in Lange's view, for example, is his argumentdire ted against Friedman that Maxwellian ele tromagneti theory did notundergo any �meaning shift� but virtually survived inta t the transition from

30 Re onsidering Friedman and the A PrioriNewtonian to relativisti physi s. Although this remark seems to be quiteun ontroversial, I think it may just make as mu h sense to say that Einsteinwas so unpleased about asymmetries within the very kernel of (the prevailingstate of) Maxwellian ele tromagneti theory that he developed the spe ialtheory of relativity, that is, a revolutionary new foundation not only forele trodynami s, but for all of physi s. In other words, riti izing ambiguitieswithin Friedman's idea of onstitutive prin iples by introdu ing an equallyun lear idea of �meaning shifts� does not really help to resolve the issue. So, Ithink, what we need is a perspe tive whi h fa ilitates a deeper understandingof the debate between Friedman and Lange.1.5 RECONSIDERING FRIEDMAN IN LIGHT OF THE ALTERNATIVEAPPROACHHaving a ounted for the alternative approa h to spe ial relativity, let usexamine more losely the very hallenge it poses for Friedman's idea of a priori onstitutive prin iples and how the latter might respond to this hallenge.It is no exaggeration to say that Lévy-Leblond devotes his whole paper toargue that the most appropriate formulation of this prin iple is as a �superlaw� onstraining all laws of physi s to have a parti ular ovarian e groupin ommon (depending on the value of σ). To put it in a nutshell, thesigni� an e of this formulation with regard to Friedman is that the postulatedsymmetry of the laws implies omplete symmetry between what Friedman alls proper empiri al laws and onstitutive prin iples. In other words, thereis no fundamental distin tion between proper empiri al laws, on the one side,and prin iples empiri ally de�ning the very spa e-time arena of these laws,on the other. Every set of laws with the Poin aré group as ovarian e group,for instan e, would in prin iple be able to fun tion as an empiri al de�nitionof Minkowski spa e-time. In parti ular, we may hoose to de�ne inertialframes empiri ally by means of 1) the prin iple of inertia in onjun tionwith Einstein's light prin iple or 2) Einstein's relativisti dynami s of 1905whi h repla ed the Newtonian laws of motion.4 Moreover, [symmetri førertil℄ �experimental on�rmation� af framework.But, we may ask on behalf of Friedman, what about the status of theprin iple of relativity itself? Not surprisingly, Lévy-Leblond ontends it tobe an empiri al postulate based on �simple physi al experien e:�4 See Ohanian (2004).

1.5 Re onsidering Friedman in light of the alternative approa h 31We know from simple physi al experien e that speed, indeed, isonly relative and an be varied from one inertial frame to theother; this is the empiri al basis of the prin iple of relativity. Weknow, though, that the same is not true for a eleration, whi his asso iated with physi al e�e ts di�erentiating various frames(Lévy-Leblond; 1976, p. 272).Hen e, Lévy-Leblond simply takes it for granted that measurements of dis-tan e and time are already in pla e, so that inertial frames be ome empiri- ally as ertainable on the grounds of �simple physi al experien e� indi atingthe very existen e or absen e of inertial e�e ts su h as Coriolis for es. FromFriedman's perspe tive, however, this is not a feasible strategy: Lévy-Leblond annot on lude his derivation of the inertial transformations obtaining be-tween inertial frames by means of experiments like the ones performed byMi helson and Morley, simply be ause the empiri al de�nition of inertialframes presupposes onstitutive prin iples that already de�ne the stru tureof spa e-time ompletely. In parti ular, these prin iples de�ne the ovarian egroup of physi al laws orresponding to the group of inertial transformations.To see this, assume we are given a spa e-time manifold M and two (say,global) inertial frames x and y mapping worldpoints p of M into R4, that is,

x : M → R4 and y : M → R

4. It now follows that the inertial transformationF between inertial oordinates (x0, x1, x2, x3) ∈ R

4 and (y0, y1, y2, y3) ∈ R4is given by F = y◦x−1. So, from Friedman's point of view, this demonstratesthat we annot take inertial frames for granted in order to obtain an empir-i al measure for σ. Be ause, Friedman would argue, the very idea of settingup an experiment in order to establish the value of σ rests on a fundamental onfusion.With this in mind, Friedman ould then noti e that all the empiri aleviden e whi h Lee and Kalotas addu e for the fa t that σ2 < ∞ followslikewise from Lorentz's ele tromagneti theory formulated against the ba k-drop of a lassi al spatio-temporal stru ture. In other words, Lorentz didnot take the �fa t that the mass of a parti le in reases with its speed� as �anindi ation that the Galilean transformations (σ2 = 0) are invalid.� What hedid instead, as we have seen, was to introdu e the hypothesis of the existen eof dynami al e�e ts aused by the motion of bodies relative to the aether.Lorentz then argued that, sin e these dynami al e�e ts also in�uen e ourmeasuring devi es, it is ne essary to introdu e a distin tion between real and

32 Re onsidering Friedman and the A Priorie�e tive (or apparent) oordinates. So, although we observe that e�e tive oordinates transform a ording to the Lorentz transformations, the orre-sponding real oordinates are still related to ea h other through Galileantransformations. The reason why the alternative approa h to spe ial rela-tivity dismisses Lorentz's explanation without a word is that the prin ipleof relativity understood as the physi al equivalen e of all inertial frames,ex ludes the very possibility of introdu ing a distin tion between real andmerely apparent oordinates.5 Hen e, dismissing the role the prin iple ofrelativity plays in Lévy-Leblond's arti le, we do not have to interpret the ex-periments just mentioned as dire t empiri al eviden e for the transition fromthe Newtonian framework to its spe ial relativisti ounterpart. The samegoes, of ourse, for the Mi helson-Morley experiments. They only on�rmthe light prin iple unambiguously, if we ex lude the possibility of introdu -ing a distin tion between real and e�e tive oordinates from the outset. The on lusion to draw, from Friedman's point of view, is thus that the alter-native derivation of the Lorentz transformations does not establish a dire tempiri al test in favor of the spe ial relativisti framework.What this approa h does larify, however, is the relationship betweenwhat Friedman alls logi al possibility as ontrasted to empiri al possibility.The derivation pro eeds by showing how the su essive addition of onditions onstraints the spa e of logi al possibilities more and more. If our su es-sively expanded set of onditions �nally singles out an unique spa e-timestru ture, it follows that this set may be applied in order to de�ne the stru -ture empiri ally: establishing the existen e of inertial frames satisfying the onditions means that the spatio-temporal arena turns out to be empiri allywell de�ned. On the other hand, establishing that no su h inertial frameexists implies for Friedman that the oordination is what he alls empiri- ally useless. To see how the more familiar de�nitions of inertial frames �tinto Lévy-Leblond's derivation, we remind ourselves that the latter openshis paper by posing the prin iple of inertia in onjun tion with the relativ-ity prin iple. On Lévy-Leblond's own a ount, the following analysis thenproofs that we an do without a �se ond postulate.� However, from Fried-man's perspe tive, it rather demonstrates the ontrary. What the analysisreveals is, �rstly, that the onjun tion of the prin iple of inertia and the5 Newton, of ourse, also subs ribes to a prin iple of relativity. But, as his adheren eto absolute spa e demonstrates, he understands it merely as an epistemologi al prin iple.

1.5 Re onsidering Friedman in light of the alternative approa h 33relativity prin iple is insu� ient to de�ne inertial frames empiri ally. Se -ondly, it demonstrates why the addition of Einstein's light prin iple or theNewtonian se ond law of motion hanges the situation. In the ase of spe- ial relativity, we simply noti e that adding the light prin iple as �se ondpostulate� orresponds to the requirement that α = c−2. In the Newtonian ase, we add the se ond Newtonian law of motion as �se ond postulate.� Wehave already demonstrated that this implies α = 0. We then observe that thethird Newtonian law of motion follows from the se ond law and the relativityprin iple. To see this, we assume the ontrary. It then follows that we maydistinguish between inertial frames on the basis of inertial e�e ts on�i tingwith the relativity prin iple.Having shown how to obtain the familiar de�nitions of inertial frames inthe two ases, we may elu idate the disagreement about the de�nition su hframes between Friedman, on the one hand, and Lange and Lévy-Leblond,on the other, as an opposition between an empiri al on eption of inertialframes and a realist one. A ording to the latter, inertial frames are de-�ned as frames of referen e in whi h for e-free parti les des ribe re tilinearmotions at uniform speed. The existen e of su h frames orresponds to theempiri al ontent of the prin iple of inertia. We may all this understandingof inertial frames realist in the sense that it presupposes the idea of for e-freeparti les. From Friedman's point of view, however, this realist on eption isill posed, be ause it is empiri ally useless: we have no independent empiri almeans of establishing whether or not bodies are a ted upon by for es. Thisimplies that it is impossible to single out inertial frames by means of theprin iple of inertia alone. Beyond the prin iples of inertia and relativity, asthe above analysis demonstrates, we have to add an extra onstitutive prin i-ple or empiri al riteria so as to make inertial frames empiri ally dis ernableand hen e empiri ally workable. In parti ular, ontrary to the realist un-derstanding, Friedman argues that the null result of the Mi helson-Morleyexperiments did not amount to a genuine empiri al on�rmation of the invari-an e of the speed of light: evaluating the laboratory frame to approximatean inertial frame pro eeds on the basis of the three Newtonian laws of mo-tion. To on lude that the null result empiri ally established that σ = cis thus plainly self- ontradi tory. However, Friedman points out, what wemay do in the light of the Mi helson-Morley experiments is either de ide toreje t the se ond and third Newtonian laws of motion in order to elevate thelight prin iple to the status of a onstitutive prin iple. Or we may hoose

34 Re onsidering Friedman and the A Priorito keep the lassi al spatio-temporal framework in order to explain the nullresult along the lines of Lorentz. The latter, Friedman tells us, managedto in orporate the null result within a lassi al spatio-temporal stru ture byintrodu ing dynami al e�e ts aused by the aether whi h pre isely render itimpossible to dis ern the aether frame empiri ally.1.5.1 Re onsidering the Mi helson-Morley experiments4. In the end: min model: ingen distinktion andet end DiSalle. Eller måske:enhver emp. teori forudsætter ST-framework. Pga. RP kan dette frameworkimpli it de�neres via eet sæt love for så at fungere som måle-hutli-hut for deandre. Hvordan det går kan vi set i overgangen fra N til E. RP som regulativtprin ip!MIN ANALYSE AFOVENSTÅENDE I LYSET AF FRIEDMANS EGENTEORI:What I want to argue is that, even if we presuppose the lassi al spatio-temporal stru ture, it is impossible to understand these experiments as gen-uine empiri al tests on Friedman's a ount of onstitutive prin iples. BeforeI pro eed let me give a short survey of the debate between Friedman andLange.Let me now turn to my analysis. The �rst thing to noti e is that Fried-man's a ount rests on the idea that any proper empiri al law presupposesthe spe i� ation of referen e frames by means of onstitutive prin iples. Seenin this light, the relativity prin iple requires that all proper empiri al lawspresuppose the very same referen e frames. Of ourse, this does not need tobe the ase: di�erent empiri al laws may presuppose di�erent onstitutiveprin iples. For instan e, in the light of the fa t that the laws of Maxwellianele tromagneti theory are not ovariant under Galilean transformations, the lassi al approa h to this theory was to refer its laws to a single frame at restrelative to the alleged aether. In other words, the advent of the theory wasseen to demand the dismissal of the relativity prin iple. But, we may nowemphasize, from Friedman's point of view this solution to the problem annotbe satisfa tory as it stands. We still need to add a onstitutive prin iple inorder to single out the �aether frame.� Without an empiri al de�nition of thisframe, the Maxwellian laws simply remain �meaningless.� Friedman himselfdoes not noti e this onsequen e of his own idea of onstitutive prin iples.This should ome as a surprise on the ground that Mi helson and Morley did

1.5 Re onsidering Friedman in light of the alternative approa h 35not pose an empiri al de�nition of the aether frame before arrying out theirmeasurements. In other words, even on the assumption of lassi al spa e-time, Friedman annot view their experiments as genuine empiri al tests. Hemay, however, reinterpret the two experiments as an attempt aimed towardsthe empiri al spe i� ation of the aether frame � the latter being de�ned as theone and only frame in whi h the Newtonian laws of motion and the ( lassi alformulation of the) light prin iple hold true.6 Having lari�ed how to give ana ount of the aether experiments whi h is in better tune with Friedman'sown pronoun ements, we may now interpret the null result as establishingthat the lassi al light postulate is empiri ally useless as onstitutive prin- iple for the Maxwellian theory. In other words, despite the fa t that the ovarian e group of the Maxwellian ele tromagneti theory is at odss with lassi al spa e-time, it seems as if any Newtonian inertial frame satis�es therequirement.=> Inden for klassisk ramme betyder null result så at LP klassisk erempiri ally useless som koordinering for Maxwells ligninger. Mao. er LP iforbindelse med Maxwell ikke et forsøg med mindre man tager forsøget atfa e value:CF: Hvad Friedman selv ligger op til: Slippe udenom de omtalte proble-mer ved bare at sige, at vi har vores klassiske spa e-time, der er velde�neret.I den foretager vi så MM-forsøget. Og det forsøg har så det resultat det nuengang har. PERIOD = Sådan som jeg forstår at Friedman vil læse Lorentz-like tilgang til MM. Dvs. som no inertial e�e t on ele tro phenom eller hvadhulen der nu stod.23.08.08: PAS VOLDSOMT PÅ med nedenstående / skriv hellere nogetnyt i forhold til sober Lorentz tolkning:Mao. bygger Lorentz' manøvre på at spa e-time ikke er / kan være em-pirisk velde�neret. Dvs. i stedet for at gøre noget ved hvad Friedman børanse for problemet, så giver han forklaring på, hvorfor det ikke kan udpeges.Fx. ved at gøre det klart, at N-IF + LP som betingelse ikke er empiriskvelde�neret pga. særlige dynamiske e�ekter, der forkorter armen på interfens-tingesten.CF: Men er det så i det mindste godt nok? Men er det gangbar vej? =>Hele Lorentz tilgang går netop ud på at empiri al well de�nedness ikke er enmulighed for os! E�e tive er ikke nødvendigvis real! Der er dif mellem absolut6 formulering af klassisk LP!!! I hvile i forhold til æteren gælder ...

36 Re onsidering Friedman and the A Prioriog apparent! Derved får Lorentz faktisk også "ødelagt N1-N3-koordinationen(hvis førstnævnte ikke allerede skulle være problemer nok). Thi æter a ts butis not a ted on! Dvs. indførelsen af æteren er i strid med N3 og uden N3 erogså Newtonian inertial frames empiri ally useless. Det har jeg været indepå før! => I dette lys: MF giver netop værktøjerne til at jorde Lorentz.Dvs. hverken LP som betingelse er på plads eller den klassiske spa e-timealene.Men inden vi foregriber del-konklusionen, så lad os vise dette forhold:=> Een ting er at han ikke får udpeget et ætersystem. Det har vi lige vist.Her burde Friedman egentlig slå bremserne i!: e�etive real tri ket svarer tilat udelukke empiri al well de�nedness "per Dekret". Og det kan Friedmanvel ikke mene er godt nok!?!?!!! Vi har mao. ingen well def. Newtonianspa e-time. Ej heller udpeget æter-system.Måske her, måske senere: Hvad Einstein gjorde i stedet for: det svarer tilat sige, at der er forskel på elerity og velo ity, eller hvordan det nu lige var.Analyse af det ved hjælp af min graf med ure tegnet ind! Og hvorfor lys erså velvalgt, dog ikke fordi den er en konvenionel stipulation.Så tilbage igen: Hvorfor er det lige at dette ikke er godt nok? Hvad erdet lige der er galt ved Friedman? Friedman siger, at Lorentz ikke stilledespørgmålstegn ved N-STs empiriske well-de�nedness. Og at det at han ikkegjorde det kan anses for en empiri al motivation / empiri al reason af 2.orden, men ikke for en empiri al reason af 1. orden: Vi har jo ikke �kseretST i MM-forsøget.Hvad skal vi mene om det? Men vi må vel kunne kritisere at framenIKKE er empirisk vel-de�neret og heller ikke kan være det, idet N3 ikke eropfyldt? Sagt med andre ord / Derudover: For at kunne være emp. riteria,dvs. for at det giver mening at kalde dem således, så skal man også værei stand til at afgøre om de er opfyldte! dvs. om de udpeger I-frame medtilfredsstillende approximation! [Ellers ender vi med Lange, hvilket Langeselv er inde på: symmetry!℄Ellers kan man vel ikke engang kalde dem for kriterier? Og det er velhvad Friedman mener med emp. useless!?!?!!! Mao. vil jeg frem til, at konst.betingelser har empirisk indhold! Kobles måske til LL's fremgangsmåde: re-stri tions. De kan dog først være operative, hvis det viser sig, at der matem-atisk set heller ikke er andre muligheder. Hvis betingelserne indskrænkerde logiske muligheder til en entydig struktur, så er strukturen empiri allywell-de�ned! Herom gerne lidt mere! => MF tager fejl, når han hævder at

1.5 Re onsidering Friedman in light of the alternative approa h 37sådanne prin ipper ikke har empirisk indhold. Lange better.Hvor Lange så tager fejl: At Maxwell survied inta t ud fra Einstein erHELT HENNE I HAMPEN!!! Det er netop derfor Einstein udvikler SRT:fordi der er asymmetrier!!! For at få ST til at passe over ens med RP. RPsom regulativt prin ip.Snakken om meaning hange er ikke et problem for Friedman. Fx. vil deto forskellige måder at de�nere IF'erne på vær således, at der hvor M-lovenegælder i den ene og helt og holdent indeholdt i den anden eller omvendt.Dvs. G-transform er M-lovene er netop Ikke M-lovene. Der hvor M-lovenegjaldt i Newton, der ville de også gælde i SRT! Det er stadigvæk således, atman kan tale om at enhver empirisk lovmæssighed forudsætter begreber omrum og tid.Min brug af DiSalle: Hvad vi bør gøre i stedet for at skelne skarpt mellememp. og konst. er at sige som DiSalle i 1995, at enhver empirisk lovmæssighedforudsætter rum og tid. Det betyder så også at vi kan bruge disse love tilimpli it at de�nere vores begreber om rum og tid. Inden for Newtons universer det således at samme frame forudsat. Det er netop at sige vi bevæger indenfor klassisk fysik. Vi har nemlig et RP-prin ip. Hvorom alting er: Lovene erempiriske. Herfra skal jeg have overgang til RP som regulativt prin ip!Jeg mangler RP som regultativt prin ip som kritik af "natural transfor-mations". => Her skal jeg tilbage til LL! Prøv at adskille de to ting: LL iforhold til ML og LL i forhold til RP! Derudover er det vel netop hvad jeghar gang i! Jeg mangler tillige at jeg anser konst. af frame som et empiriskanliggende, dvs. eksistensen af frame er et empirisk spørgsmål! Men ideenom ST-framework er dog tæt på Friedman! Der er prin ipper, der er meregrundlæggende end andre! Men pga. RP har enhver enkeltteori "ba k-loop"karakter!Husk Lange: Set i lyset af ovenstående, så vil en bestemt lov ikke pludseligvære gyldig i een frame, den førhen var antaget til ikke at være gyldig i! Detkan simpelthen ikke lade sig gøre. Men det betyder netop, at Lange for såvidt har ret i, at enkeltteorier har empirisk indhold uden bestemmelse afframe.Langes fremstilling af Maxwell er noget hø: Friedman ville kunne holdefast i, at der er tale om den samme teori, såfremt teorien viser sig fortsat atvære gyldig i den frame, som den i ST1 var tænkt at være gyldig i! Mao.skal ST2 blot indeholde ST1. Og det gør den netop i overgangen fra klassisktil relativistisk ST: I det første tilfælde gælder den kun i eet frame, der så er

38 Re onsidering Friedman and the A Prioritænkt udpeget via N1-N3 plus ekstra konstitutiv betingelse LPklassisk. I deandet tilfælde gælder den alle frames, der kun har LP som betingelse (dogogså ompatible med N1) Hvad er min kritik af Friedman i bund og grund?At eksistenen af frames er

BibliographyFriedman, M. (2001). Dynami s of Reason, CSLI Publi ations, Stanford,California. 1999 Kant le tures at Stanford University.Lange, M. (2004). Review essay on dynami s of reason by mi hael friedman,Philosophy and Phenomenologi al Resear h 68(3): 702�712.Lévy-Leblond, J.-M. (1976). One more derivation of the Lorentz transforma-tion, Ameri an Journal of Physi s 44: 271�277.Ohanian, H. C. (2004). The role of dynami s in the syn hronization problem,Ameri an Journal of Physi s 72: 141�148.Quine, W. V. (1951). Two dogmas of empiri ism, Philosophi al Review60: 20�43.Rei henba h, H. (1965). The Theory of Relativity and A Priori Knowledge,Berkeley. Transl. from German and ed. by Maria Rei henba h.

39