Cosmology: Methodological Debates in the 1930s and 1940s (Stanford Encyclopedia of Philosophy) Cite this entry Search the SEP • Advanced Search • Tools • RSS FeedTable of Contents• What's New• Archives• Projected ContentsEditorial Information• About the SEP• Editorial Board• How to Cite the SEP• Special CharactersSupport the SEPContact the SEP ©Metaphysics Research Lab,CSLI,Stanford University  Open access to the SEP is made possible by a world-wide funding initiative. Please Read How You Can Help Keep the Encyclopedia FreeCosmology: Methodological Debates in the 1930s and 1940sFirst published Sat May 18, 2002; substantive revision Wed Jun 20, 2007Sometimes, philosophy drives science. Cosmology between 1932-48provides an excellent example how explicitly philosophicalconsiderations directed the evolution of a modern science during acrucial period of its development. The following article exhibits thesephilosophical aspects of cosmological thinking in detail, beginningwith a brief sketch of the historical development of general relativitycosmology until 1932. Following this, the historical participants inthe philosophical debate are introduced, along with the basic ideas oftheir competing positions. Then the critical stages of the debate --1935-37 -- are closely explored by focussing directly upon thearguments of the participating scientists and philosophers. Finally,the concluding stage of the philosophical debate, namely, the emergenceof the steady-state theory of the Universe, is presented in the contextof its development from Popper's philosophy of science.1. Introduction2. The Lead-up to the Debate 2.1 Einstein's General Theory of Relativity 2.2 Hubble's Expanding Universe 3. Cosmology and its philosophy 3.1 Relativistic Cosmology: the majority philosophy 3.2 Milne's Philosophical Challenge 3.3 Kinematic Relativity—an alternative cosmology 4. The Great Cosmological Debate Begins: 1933-1934 4.1 Dingle's First Attacks 4.2 Two Ways to Disagree with Milne 4.3 Milne Makes Philosophical Improvements 4.4 A Major Philosophical Issue: What makes a scientific theory ‘good’? 4.5 How to Choose Among Theories and Philosophies? 5. The Triumph of Milne's Methods 1935-36. 5.1 McCrea, Walker and Robertson Adopt Milne's Methods 5.2 But Eddington Scoffd… 6. Dingle's Denoument 6.1 Modern Aristotles? 6.2 Dingle as ‘True Believer’ 6.3 Wrong from the Very Start 6.4 The Debate Goes Very Public 6.5 The Counterattack 6.6 The Coolest Voice 7. The Calm Between the Storms 7.1 Two Equal Competitors 7.2 The Origin and Evolution of Theories 7.3 Milne's Ultimate Success 8. Steady-state Cosmology 8.1 Bondi's Philosophical Origins 8.2 Enter Popper 8.3 But It's Milne In the End 8.4 Return of the Cosmological Principle 8.5 A Popperian Conclusion BibliographyOther Internet ResourcesRelated Entries1. IntroductionOne of the most vigorous philosophical debates of the century brokeout among cosmologists during the 1930s and 1940s. At the peak of thedebate, 1936-37, many of the most prominent scientists in Britain, aswell as several leading philosophers of science, had gotten themselvespublically involved. Their arguments, attacks and rebuttals werechronicled in many of the leading scientific journals, including aspecial edition of the foremost general scientific journal,Nature, devoted entirely to philosophical arguments andcounter-arguments.Methodology was the central issue of the debate, althoughmetaphysical questions also arose, particularly those concerning theactual reality of certain structures and forces imputed to the Universeby the new cosmological theories and observations. But in the end,methodology was the real goad spurring on most of the participants.At bottom, there were just two opposing positions in the debate,each of which comprised a two-point stance. On one side were thosescientists who had their roots mostly in the experimental side ofnatural science. To them, there was one and only one legitimate methodfor science. Theory construction, they believed, involved twoclosely-linked steps. First, one began from the empiricalobservations, that is, from measurements, manipulations,experiments, whose results were evident to the human senses; this isclassic empiricist epistemology. Observational results wouldthen suggest possible hypotheses to examine via further empiricaltesting. When enough data concerning the hypothesis had been gathered,logical generalization could be carried out, thereby producinga theory; this is classic inductivist logic.Opposing these inductive-empiricist scientists were those whoseroots were mostly in the theoretical side of natural science, mostespecially mathematical physics. To them, there was another, morelogically sound, method to construct theories. First,hypotheses could be generated in any fashion, although mostbelieved that imagining hypotheses which were based upon very general,very reasonable concepts—that the Universe's physical processeshad simple mathematical descriptions, for example—was the bestplace to begin; this is classic rationalist epistemology. Oncethe hypothesis had been generated, strict analytical reasoning could beused to make predictions about observations; this is classicdeductivist logic. Scientists who held this view came to becalled hypothetico-deductivists; their views about bothhypothesis generation and deductive predictions were each stronglyopposed by the inductive-empiricists.Part of the controversy may be laid to the fact that cosmology was anew science, and disputes about methodology in new sciences are notrare in the history of the sciences. What is rare about this case,however, is the vigor, sometimes even bitterness, with which thephilosophical controversy was waged. Another reason for the controversylies in the fact that cosmology is a data-poor science: observationsare hard-won and rare, and they frequently must be run throughelaborate theoretical manipulations and corrections in order to makesense at all. With a paucity of data results, scientists must rely uponphilosophical argument to undergird their views about how thescientific work should be done.One final feature of the debate must be noted. The participants arealmost universally scientists, and not philosophers. Yet this does notmuch affect the level of philosophical thinking going on; thesescientists knew their philosophy well, and they wielded philosophy'sweapons and defenses with great skill. In the end, their debate shapedcosmology into the science we know today.It will be useful to look briefly at the history of cosmologyleading up to the debate.2. The Lead-up to the DebateSince about 1700 theories about the nature and structure of theUniverse were derived from Newtonian theory, most especially his theoryof gravitation, which was used to account for the behavior of heavenlybodies and their systems. Newton's theory hypothesized aforce—gravitation—acting upon material bodies, free to moveover time within the passive, inert ‘container’ ofthree-dimensional space. Bodies, paths, and space itself exemplifiedthe classical geometry of Euclid. All these features changed with thepublication of Einstein's General Theory of Relativity, 1915-17.2.1 Einstein's General Theory of RelativityEinstein's intended his theory to replace Newton's theory ofgravitation completely. In Einstein's view, gravity was not a forceexisting independently of the spatial ‘container’; rather,gravitation arises as a curvature of the space (and time, which isnecessarily connected to space in the new theory), which means thatgeometry and gravity and astronomical behavior are all intimatelyconnected. For example, near the sun the geometrical structure, thecurvature, of spacetime changes radically, which expresses itself as anincreasing velocity of incoming orbiting bodies such as comets orsatellites. One immediate, and to some, puzzling, consequence ofEinstein's theory is that the geometry of the Universe is no longertaken to be Euclidean. Although there are several different candidatesfor the actual geometry of space, it was not known which iscorrect.It was not recognized at first that the General Theory of Relativitycould be applied to the Universe as a single, whole, individual object,thereby producing a new cosmological theory, one completely differentfrom its predecessors. Although the mathematics involved are extremelydifficult, two solutions, one by Einstein himself, the other by theDutch astronomer Willem de Sitter, were produced in just a short timein 1917. Unfortunately, the universes predicted by the two solutionswere extreme: Einstein's universe would be densely packed with matter,whereas de Sitter's would be essentially empty.Obviously, the universe as observed by astronomers did not conformat all to the description provided by either solution, a fact manyfound troubling. Moreover, no additional solutions were forthcoming(even though both Friedmann and LeMaître had developedalternatives, they remained unknown and unnoticed). For nearly twelveyears, the new cosmology appeared to be going nowhere. Then Hubble atCalifornia's Mt. Palomar made public his astonishing observations of acosmic Doppler shift, a shift toward the red in the color of lightcoming from the most distant star systems.2.2 Hubble's Expanding UniverseMost cosmologists—with the interesting exception of Hubblehimself—came to the immediate conclusion that the red shift couldonly mean that the universe was expanding. Immediately the relativitytheorists were able to interpret the expansion as a continuous changein the geometry of spacetime, which was thoroughly accounted for by theGeneral Theory of Relativity. After over a decade of stagnation in faceof the meager choice between just two models of the cosmos, Hubble'sobservations spurred theorists on to the construction of a melange ofnew models, each vying in competition with the other.In the end, it was the Belgian astronomer Georges LeMaître'stheory of an expanding universe that came to be accepted.LeMaître's model was publically proclaimed as appropriate andgenerally correct during a special session of the British Associationfor the Advancement of Science, 31 Oct 1931. Modern scientificcosmology had been officially born; because of its birth within thecontext of Einstein's theory of relativity, the new cosmology becamequickly and broadly known as Relativistic Cosmology. The modelof this cosmology is most famously that of the blowing up of a balloonpainted with dots to represent galaxies. Over time, the radius of themodel's spherical space (the balloon) increases, thereby decreasing thecurvature of the space (the balloon's skin), and increasing thedistance between the dots.Although cosmologists came from Europe and America as well asBritain, most of the work in theoretical cosmology took place inLondon, Cambridge and Oxford. Americans Hubble, Tolman and Robertsondid their work at CalTech in Pasadena, but were frequently in England;and most of the European and British workers cycled through Pasadena atone time or another. De Sitter, from Holland, and LeMaître, fromBelgium, spent important periods in England, as did various of theGerman workers. Thus, even though cosmology was done throughout theWestern world, its major concentrating point was England; our focus inwhat follows will be the same.3. Cosmology and its philosophyBecause it represented such a radical departure from previousscientific thinking about the Universe, relativistic cosmology neededto work out its philosophical underpinnings, most especially in regardto its methodology. ‘How is this new science to beconducted?’ was thus a compelling question. But method, ofcourse, is always linked to metaphysics and epistemology. A full-blownphilosophical discussion was evidently required. It came soon enough:within a span of less than a year, a vigorous debate between twophilosophically opposed camps developed. The debate required nearly twodecades to reach its full resolution. But, with the resolution,cosmology had philosophically certified its methodology within thecontext of a concensus metaphysics and epistemology. Before going intothe details of the debate, however, several general points should benoted. Let us turn to the details of the origin of the debate.3.1 Relativistic Cosmology: the majority philosophyTo begin with, the cosmological thinking of the majority ofscientists—including Eddington, de Sitter, Robertson, Tolman, andtheir colleagues—had betrayed a relatively unexamined, andapparently uncontroversial cluster of philosophical perspectives: onthe metaphysical side they held a modest sort of explanatoryrealism—if an accepted theory referred to entity x,then x was acceptable as a genuinely, physically real object;to this metaphysical stance was coupled a methodology exhibiting aclassic sort of inductive empiricism—scientificknowledge consisted of generalizations built up from individualempirical observations. But this cluster of views did not go longunchallenged. In early July 1932, just nine months after relativisticcosmology became the concensus during the British Association meeting,Oxford astrophysicist E. A. Milne published a short article inNature which directly attacked the current philosophicaltenets, proposing their replacement by a new cluster of views, one asradical as the new science it purported to undergird.3.2 Milne's Philosophical ChallengeMilne's metaphysical views were based in positivism, most especiallyin operationalism: only those objects whose properties couldbe directly revealed by some observational procedure, or operation,were to be counted among the real. Thus, for Milne, reality did notcontain the usual relativistic cosmology referents “curvedspace”, “expanding space” or even“four-dimensional spacetime”, simply because none of theseentities were operationalizable. Milne held that ‘what you sawwas what you got’; since “curved space” of variousgeometries couldn't be observed, space was just as itlooked—Euclidean. In the same way, the expanding of the Universewas a genuine expanding—each galaxy was retreating from eachother—not just a change in the geometry of the curvature, as itwas for the relativists. Moreover, in place of relativistic cosmology'sinductive empiricism, Milne opted for a hypothetico-deductiverationalism. Cosmologists, Milne believed, were bound to dream upany and all possible models of a universe, and then deduce what, ifany, observable consequences followed from their hypotheses.Hypothesizing could be based upon just about anything, although Milnebelieved that certain very general rational principles derived fromaesthetic beliefs about universal order and regularity would be themost fruitful. His ‘cosmological principle’,namely, that every cosmologist in the universe should look out upon thesame cosmos, was the prime example of such thinking. Later, Bondi wouldfound Steady-state Cosmology on an even more general version of Milne'sprinciple, which he called the ‘perfect cosmologicalprinciple.’3.3 Kinematic Relativity—an alternative cosmologyMilne's philosophy of cosmology came with a closely associatedcosmological model, kinematic relativity, so-called because ofits tight links to the kinematics of Einstein's Special Theory ofRelativity. Kinematics, in Einstein's Special Theory, is especiallyconcerned with observers trying to make measurements of the behavior ofobjects moving in systems relative to themselves. According to Milne'sunderstanding, these measurements could only be made by the observerssignalling among themselves using light or other electromagneticradiation, using clocks to time the signals. In the end, allmeasurement—even space and velocity—reduced to timing thesignals as they went from one observer to another. This idea ofmeasurement represented a revolutionary simplification of previousideas, and held philosophical interest for that reason alone. Therewere practical consequences as well. As Bondi later remarked,“Milne's idea led straightaway to the radar speed gun!”Milne's kinematic relativity and its underlying philosophy bothimmediately brought careful scrutiny, not to mention controversy.4. The Great Cosmological Debate Begins: 1933-1934Eddington was the first to attack Milne's views. In a series oflectures given at Harvard during late ‘32 and published early in thenew year as The Expanding Universe, Eddington denied theefficacy of both operationalism and hypothetico-deductivism, and notonly defended explanatory realism, but strengthened his ontologicalposition heroically: the theoretical entities of relativistic cosmologywere not just plausible, they were so necessary to understanding theuniverse, that cosmological knowledge was essentially impossiblewithout them. (Eddington 1932, p. 19)4.1 Dingle's First AttacksFew others would ever go so far as Eddington's ontological heroism;yet epistemological and methodological heroism in the fight againstMilne was not rare. Chief hero in this aspect of the attack on Milnewas Herbert Dingle, a highly respected astrophysicist, andthen-secretary of the Royal Astronomical Society. Dingle's initialforay appeared as a response to Milne's first detailed presentation ofkinematic relativity. (Milne 1933) After claiming that while kinematicrelativity did not differ appreciably from relativistic cosmology inits mathematical formalism or observable consequences, Dingle assertedthat, on the other hand, it invited special criticism because itrenounced “the fundamental principles of scientificmethod,” namely, “Newton's principle of induction fromphenomena.”(Dingle 1933 p178) Dingle was never to relent in hisattacks upon Milne's hypothetico-deductivism, at all times rejectingthe methodology as even a possible candidate for acceptance by genuinescience.Dingle's article appeared back-to-back with an appraisal ofkinematic relativity by the important American cosmologist H. P.Robertson. (Robertson 1933a) Robertson focussed upon Milne'shypothetico-deducivism as well, noting that the cosmological principlein kinematic relativity functions as an a priori rule, ratherthan as an empirical generalization, its status in relativisticcosmology. Robertson otherwise is not especially taken with Milne'stheory, limiting himself to remarks suggesting that, where they can becompared, kinematic relativity and relativistic cosmology apparentlyare similar in physical content. As we shall shortly see, Robertson'slater work strongly belied this earlier apparent indifference toMilne's theory.4.2 Two Ways to Disagree with MilneRight from the start, cosmologists differed in their opinions aboutboth the physical content of Milne's theory, and its underlyingphilosophy. Dingle disliked Milne's methods, but found the theoryitself of not much interest. Robertson initially agreed with Dingle,but within a short time had significant changes of heart. Eddingtondisliked both the theory and its philosophy, finding them far toodeviant from what was typical, i.e., relativistic cosmology and itsmainstream philosophy. Younger cosmologists such as McVittie andMcCrea, students, respectively, of Eddington and Whittaker, soon joinedthe fray. McVittie initially found the physics of kinematic relativityquite interesting, and quite different from the physics of relativisticcosmology. (McVittie 1933b) But Milne's philosophy was something else;the strict empiricism McVittie had earlier revealed (McVittie 1933a)made him equally unhappy with both Milne's rationalism and hishypothetico-deductivism.McCrea's remarks were among the most perceptive and favorable.(Kermack and McCrea 1933) While he thought that Milne's operationalistcriticisms of curved and expanding space were of little import, McCreawas the first to notice the parsimony and elegance of Milne's strictlykinematic solution to the problem of the origin of the universe'sexpansion. Since a search for such a solution had vexed relativisticcosmology for several years (McVittie 1931), McCrea suggested thatMilne's mechanism should be immdiately shown to be part of relativisticcosmology. (Kermack and McCrea 1933 p. 529)Clearly, the so-recently won consensus about relativistic cosmologyand its philosophy had dissolved into confusion and controversy overMilne and his methods.4.3 Milne Makes Philosophical ImprovementsOver the next year or so, Milne made strenuous efforts to elucidateboth kinematic relativity's physics and its philosophy, beginning, aswould be his wont, with the philosophy. In October, Milne addressed thePhilosophical Association, giving an explicit and detailed analysis notonly of his philosophical views, but also of their history, which, heclaimed, extended back to Locke and Hume (Milne 1934a) His descriptionof the two opposed methods—inductive empiricism vs.hypothetico-deductivism—is quite clear and useful:Strictly speaking, physics has no philosophy. It hasmethod…Now the methods of theoretical physics seem to bereducible to two species, the method of starting with concepts and themethod of starting with things observed. …When a subject isdeveloped from concepts the concepts play the part of the termsoccurring in the axioms of geometry…. The concepts are undefinedsave as being governed by propositions of which they aresubjects.Milne's commitment to axiomatization is notable here. It was basedin his earlier admiration for the work of Whitehead and Russell(Crowther 1970); commitment to axiomatization in cosmology, once havingbeen initiated by Milne, would be an enduring hallmark of the work ofmany, including both Robertson and Walker.Three weeks after this address, Milne spoke on related topics at themonthly meeting of the Royal Astronomical Society. His main point wasthat theories differed only insofar as their concepts could be cashedout in observations deduced from them. Eddington took strong exceptionto Milne's arguments, claiming in response that kinematic relativityand relativistic cosmology differed more importantly in their ontologythan in their consequences. Eddington was especially concerned withdifferences in the spacetime-geometry each theory ascribed to theworld. For Eddington and his colleagues, the equivalence of gravitationand spacetime geometry was a genuine reality, a feature of the physicalworld, just as real as suns and moons and stars.4.4 A Major Philosophical Issue: What makes a scientific theory ‘good’?Milne was having none of it. In the next month'sObservatory—the informal monthly publication of theRoyal Astronomical Society—he took Eddington and histheoretical-realist colleagues to task, concluding that “theoriesdiffer simply and solely when their predictions as to phenomenadiffer”; most importantly, “this method of comparisonavoids all reference to distance-assignments, world-geometry, schemesof projection or the like.” (Milne 1934b) In other words,metaphysics was to be avoided in cosmology; space, spacetime, geometryand the like were to be rejected as scientific realities, replaced byreference simply and solely to observations. The only realities,according to Milne, were what could be reported among observers aboutlight signals and clocks.During 1934 Milne worked together with his new student A.G. Walker.Walker never evinced much interest in the philosophical aspects ofkinematic relativity, choosing instead to focus tightly upon workingout the physical details of the theory itself. He had immediatesuccess. (Walker 1934) One of his important conclusions was that otherauthors, specifically McVittie and Robertson, were wrong to concludethat the physics of Milne's theory ultimately corresponded torelativistic cosmology: “Milne's system is fundamentallydifferent from that of general relativity.” (Walker 1934 p.489; emphasis in original)4.5 How to Choose Among Theories and Philosophies?In an important review of the entire confused situation betweenkinematic relativity and relativistic cosmology, McVittie confessedthat “experimentally it seems hopeless to discriminate betweenthem…at present the choice is almost entirely a matter ofpersonal taste.” (McVittie 1934 p. 29) At almost the same time,de Sitter took on Milne in serious fashion. (deSitter 1934) Respondingto Milne's methodological challenge, he showed that, indeed, it ispossible to formulate relativistic cosmology in axiomatic fashion, justas Milne had formulated kinematic relativity “fromconcepts.” But de Sitter explicitly rejected Milne'sphilosophical use of the cosmological principle, “which assertsthat statistically the world pictures of two different observers mustbe the same.” His objection is founded on the matter-of-fact that“we have, however, no means of communicating with otherobservers, situated on faraway stars, or moving with excessivevelocities.” (deSitter 1934 p. 598) So much for rationalprinciples as hypotheses!The year in cosmology ended almost as confused as it had begun, withone exception: Milne had gotten much clearer about his philosophicalviews, and was applying them to an exhaustive presentation of hiscosmology, theory and philosophy. His book Relativity, Gravitationand World Structure (Milne 1935) would be published in just a fewmonths.5. The Triumph of Milne's Methods 1935-36.The new year marked a sudden change. In short order, McCrea, Walkerand Robertson succumbed to Milne's methodological recommendations:first, to carry out an operationalist paring of non-observationalconcepts, then, secondly, to embed the resulting minimalist concept setin an axiomatic hypothetical-deductive structure. Thus was the famousRobertson-Walker spacetime metric born.5.1 McCrea, Walker and Robertson Adopt Milne's MethodsMcCrea's effort operationalized the concept of“distance”, principally and originally by comparison ofcertain elements of Newtonian cosmology and de Sitter's axiomatizedversion of relativistic cosmology. (McCrea 1935) Walker's paperspecifically eschewed use of “any indefinable concepts”, inparticular, he did not assume that the “associated metric [ofrelativistic cosmology] has any a priori physicalsignificance.” (Walker 1935) Robertson's article, the first ofthree, is the most important, both in its content, and in the signal itsends, namely, that one of the original mainstream relativisticcosmology proponents has adopted a major element of Milne's newphilosophy for cosmology. (Robertson 1935) Robertson's conclusionexhibits this point clearly and explicitly:We have examined, from the operational standpoint, theproblem of determining the most general kinematical background suitablefor an idealized universe in which the cosmological principle holds.Allowing the fundamental observers the use only of clocks andtheodolites, and granting them the possibility of sending and receivingwe have shown that for each given mode of motion x(t) therenecessarily exists a quadratic line element which is invariant, in formas well as in fact, under transformation fqrom one fundamental observerto another. (Robertson 1935 p. 300)Unlike de Sitter, Robertson accepts the cosmological principle, repletewith its observers on far-separated particles. Moreover, as thisstatement shows, Robertson is intimately familiar with Milne's latestoperationalist reduction: space is to be reduced to time measurementsgiven by clock readings on signals exchanged between observers.Robertson gets this idea from Milne's book, which he had earlierreviewed (but which was only subsequently published) forAstrophysical Journal. (Robertson 1936) 5.2 But Eddington Scoffd…Eddington disparages these same methods. In his scathingNature review of Milne's book, he rejects Milne'shypothetico-deductivism, his cosmological principle, and, above all,his operationalism: “When I visit the Cavendish Laboratory, I donot find its occupants engaged in flashing light-signals at each other,but I find practically everyone employing rigid scales or theirequivalent.” (Eddington 1935, p. 636) Whittaker's review was notso negative as Eddington's. (Whittaker 1935) While the senior physicistrejects Milne's operationalism and attacks upon the geometricalcommitments of relativistic proponents, he is considerably moreforgiving about Milne's hypothetico-deductivism, and even goes so faras to remark Milne's “brilliant record in astrophysicaldiscovery.” Nonetheless, Milne's break with a tradition includingat least “Einstein, de Sitter, Friedmann, LeMaître, Weyl,Eddington, H.P. Robertson and others” is to be regretted.(Whittaker 1935 p. 179) Perhaps, along with Eddington, Whittaker hopesthat soon “Professor Milne will return to orthodoxy.”(Eddington 1935, p. 636)But Whittaker's view on Milne must be put into the perspective heheld on the whole ongoing debate. As he saw it…a lively debate is in progress at the presentmoment between Sir Arthur Eddington and Dr Harold Jeffreys ofCambridge, Professor Milne of Oxford, Sir James Jeans, and ProfessorDingle of the Imperial College, the subject being the respective sharesof reason and observation in the discovery of the laws of nature.(Whittaker 1941, p. 160)But lively debate is far too gentlemanly a description for what nowoccurred. After holding his ire somewhat in check for—as he sawit—already far too long, Dingle finally erupted. 6. Dingle's DenoumentControversy over Milne and his philosophy reached a crescendo inmid-1937. Dingle, his stew having finally boiled over, wrote privatelyto the editor of Nature, first castigating the rampantcosmological ‘mysticism’ passing itself off for science,and then offering to produce an article taking the sword to the mysticsthemselves. His offer was immediately accepted. The result was Dingle'snotorious “Modern Aristotelianism”, a polemical diatribechiefly against Milne, but aimed as well at Eddington and Dirac onaccount of their “betrayal” of the scientific method ofNewton and his fellow members of the Royal Society. (Dingle 1937)6.1 Modern Aristotles?The article is remarkable both for its style and for its content.Dingle's style in the article is vituperative. Thus, emotionally-loadedterms such as “paralysis of reason,” “intoxication ofthe fancy,” “‘Universe’ mania”, and thelike frequently appear, these to be topped only by references to“delusions,” “traitors,” and, of course,“treachery,” each associated with one or more of the guiltyparties. (Dingle 1937, p. 786)Above and beyond his extreme language, Dingle makes certainsubstantive claims bearing directly upon central philosophicalquestions. The issue, as he sees it, is nothing more than the question“Whether the foundation of science shall be observationor invention” (Dingle 1937, p. 786). As always, talk about‘foundations’ is philosophical talk. The two opposingpositions Dingle here calls “foundational” involve views onboth method and epistemology, suitably tangled together. Dingledelineates the opposed alternatives as follows. The way of truescience, he claims, shows that “the first step in the study ofNature should be sense observation, no general principles beingadmitted which are not derived by induction therefrom.” (Dingle1937, p. 784) Stated more explicitly, Dingle here argues that authenticscience is empiricist in epistemology (scientificknowledge is founded in sensory observation), andinductivist in method (general principles are reachedvia inductive logic). Opposed to this view, he argues, is “thedoctrine that Nature is the visible working-out of general principlesknown to the human mind apart from sense perception.” (Dingle1937, p.787) As representative of this latter view Dingle cites Milne,and refers in particular to Milne's claim that “it is, in fact,possible to derive the laws of dynamics rationally…withoutrecourse to experience.” (Milne 1937, p. 329) Obviously, Dingleis here arguing against the view, Milne's view, that authentic sciencemay be rationalist in epistemology (scientificknowledge is founded in pure theoretical reasoning apart from senseperception), and hypothetico-deductive in method(general principles are justified by their deductively implying correctobservations).Along with Milne, Dingle indicts Eddington, and, by implication,Dirac, all three of whom, Dingle believes, are guilty of inventingscientific hypotheses by free mental imaginings rather than by strictimmersion in observations and observational data.6.2 Dingle as ‘True Believer’What is going on here? Put bluntly, Dingle is an old-fashionedempiricist and inductivist. He believes that the only way to do truescience is to first collect data, then, and only then, to hypothesizeon the basis of that data. Observation, then hypothesis. As he sees it,Eddington, Milne and Dirac have got it exactly backwards. They first(as he terms it) assume an hypothesis, then, and only then, go aboutcollecting data. Except, according to his lights, the data isn't evercollected: “to [the Aristotelians'] modern representatives itseems as though a fancy is no sooner in the head than it is on paperand sent for publication.” (Dingle 1937, p. 785) Obviously Dingleis simply wrong; it never occurred to his opponents that hypotheseswould not be followed immediately by attempts atdeductive prediction of observational consequences. But it was enough,in Dingle's mind, that they didn't use induction, for them to comeunder blame.6.3 Wrong from the Very StartBut there is something else at work here as well. Dingle doesn'tobject solely to his opponents' lack of inductive logic. Of equalimportance is the fact that they find the source of their hypotheses infairly general principles, wide-ranging rational proposals about thestructure of the universe at large. These principles Dingle takes to bea priori, in the most pejorative sense of that term. They arephantasms, “chimeras” he calls them, which seduce theimaginations of his opponents, and lead them and their dumb-struckadmirers away from the genuine, authentic method of science.This is what really sticks in Dingle's craw. In turn,Eddington, Milne and Dirac are chastised, each for something slightlydifferent, but at bottom the same, namely, they one and all“appear as a victim of the great ‘Universe’mania.” (Dingle 1937, p. 786) In the end, Dingle believes, thedanger of this new ‘methodology’ is real, and serious. Ashe notes in conclusion:Nor are we dealing with a mere skin disease which timeitself will heal. Such ailments are familiar enough; every age has itsdelusions and every cause its traitors. But the danger here is radical.Our leaders themselves are bemused, so that treachery can passunnoticed and even think itself fidelity. It is the noblest minds thatare o'erthrown…the very council of the elect can violate itscharter and think it is doing science service. (Dingle 1937, p.786)Here Dingle obviously goes over the top. Yet overblown as it is,there is no doubting his sincerity: Milne and the other cosmologistshave betrayed the true science bequeathed them by their ancestors inthe Royal Society.How could Dingle be answered?6.4 The Debate Goes Very PublicThe response arrived three months later, on 12 June. On thisparticular Saturday in June, Nature published a fifteen-pagespecial supplement as No. 3528. Contained within were contributionsfrom sixteen “representative investigators”, as the editorreferred to them, each responding to “ModernAristotelianism” Nature's Editor, R.A. Gregory,introduces the occasion by noting that “in Nature of May8, we published an article by Dr. Herbert Dingle entitled ‘ModernAristotelianism’”. Because the article, as Gregory goes onto say, “created considerable interest”, Nature“decided to invite further contributions on the subject from anumber of representative investigators.”“Created considerable interest” is, to understate theissue, an understatement. Some of the contributors were quite obviouslylivid with rage and other volatile emotions. Others, such as Milnehimself, who had come in for particularly scathing criticism inDingle's article, were patient and careful in rebuttal. Each of thesixteen contributors to the special article chose a side in thecontroversy, either pro Dingle's inductive empiricism, and con Milne etal.'s rationalist hypothetico-deductivism, or vice versa. Remarks madeby the participants exhibit the full diversity of philosophy of sciencein their contemporary community. Dingle's views, in particular, werenot without favor.Harold Jeffreys, F.R.S., noted geologist and astronomer, and authorof a well-regarded philosophy of science book ScientificInference (1957), led off with a nice ad hominem: “Withoutusing induction, Milne and Eddington could not order their lives for aday, and what they are really asserting is that they are entitled touse special axioms in physics, for which no need has been shown.”Jeffreys' criticism here of course ignores the role of deductiveobservations in justifying the “special” axioms. Theproblem, as Jeffreys sees it, originates in the perpetrators'“belief that there is some special virtue in mathematics.”L.N.G. Filon, F.R.S., vice-chancellor of the University of Londonagrees on this point, noting that “some men of science appear tothink that they can solve the whole problem of Nature by someall-inclusive mathematical intuition.” R.A. Sampson, theAstronomer Royal, focusses upon the rationalistic aspects of the‘modern Aristotelians’, to wit, for their “framing atheory independent of experience, such as is denounced in Dr. Dingle'sarticle”, which produces work not unlike that “of a poet orother humanist, who gives us at most a number of illustrativecases.”6.5 The CounterattackBut Milne, Eddington, and Dirac had their supporters as well. N.R.Campbell, whose theory of science was already well-known, makes anuncontroversial interpretation of the affair. “Science” hebegins, “(or at least physics) has long consisted of two distinctbut complementary activities”, one of which is experimental andempirical; “its procedure is induction.” The other activityattempts to provide explanations of scientific laws, which explanationshave the “pecularity” that “they often (not always)predict new laws in addition to explaining old ones.” Campbellcannot resist ending on an ad hominem of his own: “If he [Dingle]does not deem it important to observe the distinction between what isand what is not demonstrable experiment, surely he should welcome amovement to amalgamate the Royal with the Aristotelian Society.”Indeed.G.J. Whitrow, then a young lecturer at Christ Church, Oxford,returns to the mathematical theme. Dingle, he argues, “not onlyattacks the particular methods adopted by contemporary mathematicalinvestigators in relativistic cosmology, but even refuses to admit thatthis subject is worthy of scientific investigation as it is based notonly on experience but also on reason.” Hypotheses, by thislight, may originate rationalistically as well as any other way,certainly there is no problem with this.6.6 The Coolest VoiceThe clearest, most temperate discription of the issues at hand isgiven by young cosmologist William McCrea, then professor ofmathematics at Queen's, Belfast, and editor of the R.A.S.'sObservatory. Not to be outdone by Jeffreys, McCrea begins withan ad hominem of his own: “Dr. H. Dingle's objection to‘modern Aristotelianism’ seems to be itself what he wouldcall Aristotelian rather than Galilean.” In other words, Dingleraises a non-empirical objection about Milne et al.'s non-empiricism!But McCrea soon gets to the heart of the matter, the role ofhypothetico-deductivism in mathematical physics:What Dr. Dingle has done is to reopen the question of therelation of mathematical physics to experimental physics, since heclaims to detect a new and perverted point of view in the former. Now asystem of mathematical physics, apart from the alleged perversion, isthe working out of the mathematical consequences of certain hypotheses.The worth of the theory is judged…by the closeness of theagreement of its predictions with the results of observation, and alsothe number of phenomena which it can so predict from the one set ofhypotheses. The scientific attitude is, not to cavil at the attempt,but to see if it is successful.This is an absolutely standard interpretation of how the H-D methodworks. Throughout his own writings, beginning right from his inaugurallecture in Oxford (Milne 1929), Milne had subscribed to precisely thesame interpretation of the Hypothetico-Deductive (H-D) method. Whateverthe controversy is about, the issue is not how to interprethypothetico-deductivism. That much is evident.Moreover, it is quite clear that Dingle et al. are not mountingopposition to something we, today, would consider philosophicallyradical; rather, they are objecting to what, today, would be consideredcompletely unobjectionable. Given today's acceptance of the H-D method,yet its rejection by otherwise well-regarded scientists at that time,it seems to follow that it was, at least in part, this debate and itsfollowup which settled the issue. In any case, Dingle and hissupporters generally went silent, restricting their activities for themost part to books, or relatively positive statements of their ownpositions. (A.D.R. 1938, Dingle 1938) Things settled down, just in timefor the War.7. The Calm Between the StormsDuring the next several years, it became evident that Milne'smethods, and kinematic relativity as well, had reached respectability.One important sign of this progress was exhibited at an early 1939joint meeting between the Royal Astronomical Society and the PhysicalSociety of London, The meeting had as its goal a thorough review of thesituation in cosmology. McVittie was chosen to present theobservational situation; his report was soon published. (McVittie,1939) Reviewing the theoretical situation was George Temple, one of themost highly respected mathematicians of the time. Temple's report sawprint almost immediately. (Temple 1939) Within a short time, Temple'spaper took on the role of successor to Robertson's definitive 1933“Relativistic Cosmology.” (Robertson 1933b)7.1 Two Equal CompetitorsBoth McVittie and Temple presented kinematic relativity andrelativistic cosmology as equal competitors in accounting for thecosmological observations. Unfortunately, as McVittie noted,observations could not, at that time, discriminate between the twotheories. Temple's analysis of Milne's work praises its simplicity andelegance, and refers in particular to its operationalism andaxiomatization, which “start from a completely novel discussionof the correlation of measurements made by different observers in termsof light signals only.” (Temple 1939, p. 468) Throughout the restof his discussion of the two theories, Temple utilizes Milne'slight-signal correlation method, explicitly rejecting rigid-rodtransport for distance measurement. Milne's methods have triumphed.Later that year McCrea publishes an important paper inPhilosophy of Science. (McCrea 1939) Put most simply, thepaper starts out to defend Milne's methods, but ends up by presenting afull-blown and interesting, although quite unhistorical, account of theevolution and structure of physical theories.7.2 The Origin and Evolution of TheoriesMcCrea's overall view is that theories are set up to behypothetico-deductive in structure. His account is based on his view ofthe evolution of theories of space-time and mechanics, beginning withNewton, through the General Theory of Relativity and ending inkinematic relativity. His argument reduces to the claim that, insofaras Milne and e.g., Newton, can be shown to follow the same procedure,any attack upon Milne is also an attack upon Newton. First, he stateshis goals in the paper.The first goal is to emphasise how each theory leaves us in aposition in which the succeeding one appears as a perfectly naturalnext step in the development of ideas. (McCrea 1939, p. 137) McCreaembeds this argument in an account of how analogue models (à laCampbell) are used to set up new theories—this is essentially anaccount of how discovery might proceed in linking an older theory withits successor.The second goal is to show how, in spite of superficialdifferences in character, the theories in question all necessarilypossess the same general structure constituted by the presence ofhypotheses, from which certain general mathematical relations arededuced, which in their turn are used to predict relations betweenobservable quantities. As McCrea notes, “this study may claim aninterest of its own, but it is presented also for a furtherreason” namely, thatit has been contended [by Dingle, most especially] thattheories like Milne's represent a fundamentally new outlook on the partof some theorists, in that such theories are purely mental constructsdivorced from experince of the physical world. We shall see that on thecontrary Milne's theory is easily brought into line with the others insuch a way that this criticism is neither more nor less true of it thanof the rest. (McCrea 1939, p. 138)In McCrea's discussion of the theories he asserts that “theconsituents [of the theories themselves] which are of physicalsignificance are sets of mathematical relations, coupled with sets ofrules of interpretation” which yield, “after observationaltest, descriptions rather than explanations of physicalphenomena.” According to McCrea, one real advantage of his viewis that it “leads to simple criteria for comparing the merits ofdifferent theories.” Finally, on the metaphysics of the originalhypotheses, McCrea claims that “the initial hypotheses from whichthe mathematical relations are deduced do not ultimately have anydirect physical significance.”McCrea's paper, published in the leading philosophy of sciencejournal of the time, is the final imprimateur on Milne's views.7.3 Milne's Ultimate SuccessThree years later, Milne was awarded the James Scott prize, the mostprestigious award for ‘natural philosophy’ in theAnglophone world. Milne's lecture title is telling: “FundamentalConcepts of Natural Philosophy.” (Milne 1943) Although Milne doesconcede to Dingle that he no longer believes that it is possible todeduce physics completely in the absence of reference to phenomena, forthe most part his award lecture is a long reiteration of his previoustwelve years' work in cosmology.One year later, Milne received his ultimate accolade, election aspresident of the Royal Astronomical Society. In his inaugural lecture,Milne again reviews his work, but adds two remarks of interest. First,he modifies his earlier view that theories are acceptable solely on thebasis of their successful predictive power; to this, he now adds that atheory cannot be accepted as satisfactory unless it is philosophicallysatisfying. (Milne 1943, p. 120) Secondly, on a personal note, headmits that he is still amazed at the outcry that his theory and itsphilosophy caused. Milne here is being a bit disingenuous. In manyplaces in his letters he not only recognizes the outcry, he delights init, and seeks to provoke it even more. (Milne 1932-37, 12 May 35; 28Jul 36)From this point onward, cosmology's philosophy is no longer directlyinfluenced by Milne himself. Moreover, kinematic relativity began tostagnate as a research programme; except for Whitrow, Milne had no newstudents, and failed to attract any new converts to the theory. Hiswork was done. But his philosophical influence didn't end, in fact itwasn't to crest until the end of the 40s in the work of another man,Hermann Bondi. Again, however, a storm was generated by Milne'smethods, even though they were now in the hands of another.8. Steady-state CosmologyIn 1948, a young mathematician, Herman Bondi, in concert with twoclose friends Thomas Gold and Fred Hoyle, proposed a radical newcosmological theory, the Steady State theory. This theorydiffers from the basic picture shared by both kinematic relativity andrelativistic cosmology, namely, that of a universe with a definiteorigin in a small, dense knot, followed by evolution into the universewe have today. According to Bondi's theory, the universe as far backinto the past as we might look would always look the same; there was noevolution, there could be no “fossils”, as Bondi calledputative evidence of a universe different in the past from our presentone. What we observe today is the same state of a universe that hasbeen and always will be steady. Bondi came to his notion of the steadystate primarily from his commitment to the philosophical components ofMilne's work, most especially the methodology of rationalism plushypothetico-deductivism; additionally, Bondi coupled to these Milneannotions some ideas taken directly from the philosophy of KarlPopper.8.1 Bondi's Philosophical OriginsBondi reveals his philosophical commitments in several ways. First,he argues against induction and extrapolation from small-scaleexperiment, that is, against the inductive empiricism of Dingle et al.Secondly, he argues in favor of hypothesis and deduction, that is, infavor of Milne et al. Finally, he specifically remarks the excellenceof Milne's Methods, and the theory—kinematicrelativity—created therefrom, and remarks the significance ofthese elements in the creation of his version of the new steady-statecosmology.From the very beginning Bondi admits the validity of both positionsin the methodological debate:In particular, there are two important approaches to thesubject [cosmology] so different from each other that it is hardlysurprising that they lead to different answers...The contrast betweenthe ‘extrapolating’ and the ‘deductive’ attitudes to cosmology is verygreat indeed. (Bondi 1960), p. 3-5)The extrapolating approach, which Bondi sometimes calls theempirical school, is represented by Dingle, McVittie, andtheir colleagues. Opposed to the extrapolative approach is thedeductive approach, which “is reached frominvestigations in the borderland between physics and philosophy.”Milne is obviously the major proponent of this view. Although Bondifinds good points in both approaches, he also finds problems in bothapproaches. In the end, cosmology is the worse for excesses fromeither end of the spectrum: Just as some adherents of the ‘empirical’school tend to regard cosmology as a testing ground for theirextrapolations and as a legitimate playground for the geometers, sosome adherents of the deductive approach appear to regard cosmology asa purely logical subject. (Bondi 1960, p. 7)In this latter case, the deductive extremists, in their mathematicalzeal, seem to forget that cosmology, after all, shouldhave some relation to observation: “To them all that is ofinterest in a theory is its logical character, not its relevance to theinterpretation of observational data.” Obviously, this dangermust be avoided: according to Bondi, deductivism can be ascientific approach in cosmology only if itspostulates (or axioms) are candidates for disproof. 8.2 Enter PopperClearly, with this reference to the connection between science anddisproof, Bondi has added a distinctly Poppererian element to thedeductivist methodology, one which had not previously appeared in theworks of any of the earlier members of the hypothetico-deductiveschool. According to Popper's philosophy of science, a theory canlegitimately be called “scientific” only if that theorymakes a prediction that, in principle, can be shown to be false, orfalsified, to use Popper's own term. Thus astrology, forexample, fails to be a scientific theory because it cannot befalsified: although astrology seems to make predictions, thesestatements about the future are so vague, so general and abstract, thatthey cannot be tied down to definite claims about observations to bemade at a definite time and place. Hence there is no explicitobservation to be made in falsification. Astronomy, in comparison,makes explicit, specific predictions about what will occur in the skyon such-and-such a date, in such-and-such a place. If the predictionfails, then we know that the element of astronomical theory which madethe prediction is deficient, maybe even false.Cosmology is a borderline case: since observations of cosmologicalsignificance are so rare and hard-won—Hubble's observation of thered shift was one of the first solid ones—it is very difficult,not to mention brave, to tie one's cosmological theory to Popper'sfalsificationist principle as a guarantee of scientific acceptability.But this is exactly what Bondi did.Much later Bondi was to make explicit his debt to Popper:I think the person from whom we had most help on thephilosophical side was Popper. His analysis of science encouraged oneto be imaginative, and encouraged one to go for something that was veryrigid and therefore empirically disprovable. (Bondi 1990, p.194)8.3 But It's Milne In the EndYet Bondi's major philosophical debt was to Milne. According toBondi, Milne's theory was through and through deductive, which wasreason enough for some of his colleagues to condemn it:The aim of this discipline [= kinematic relativity] is todeduce as much as possible merely from the cosmological principle andthe basic properties of space, time and the propagation of light. Thebeauty of this, as indeed of any deductive theory, rests on the rigourof the arguments and the small number of the axioms required...When thetheory was first developed it met with great hostility and wascriticized very severely, often unjustly, and sometimes frivolously.(Bondi 1960), p. 123)In addition to his admiration of Milne's H-D methodology, Bondi hashigh praise as well for Milne's operationalism, particularly its use indefining distance: Imperfect as Milne's definition of distance may be, it isvery much better than the ‘rigid ruler’ one used in mostother theories…Milne's definition of distance, by no meansperfect as it is, is probably the best yet devised. (Bondi 1960, p.126-9)In the end, Bondi sums up Milne's contributions with no uncertainpraise: The foregoing brief description will have indicated theremarkable success of kinematic relativity in attempting to use thecosmological principle not only for the construction of the substratumbut as chief guide in formulating ordinary physics. In this respect itdiffers greatly from all other cosmologies which either rely on aconventionally obtained body of physics or have not yet succeeded indrawing conclusions of local interest from the cosmological principle.(Bondi 1960, p. 136)8.4 Return of the Cosmological PrincipleHere Bondi speaks of Milne's cosmological principle. According toMilne's principle, every observer in the universe should get the sameworld picture, that is, should make precisely the same observations ofthe universe at the same moment as any other observer. (Milne 1934b)Uniformity over spatial slices is guaranted by Milne's invoking of theprinciple. Yet Milne's universe evolves, it changes its form over time.Hence it has no temporal uniformity. Bondi felt that this raised thepossibility that physics itself might change over time. Because of thisrisk, Bondi generalized Milne's cosmological principle into what hecalled the perfect cosmological principle [=PCP]. According tothis principle, all observers at all places and at alltimes will look out upon the same unchanging, unevolving,universe. Such a universe is a universe in a steady-state—hencethe name.Clearly, PCP is a daring, indeed heroic, interpretation of amethodological necessity. Forty years after the fact, Bondi describedthe “philosophical attitude” which underlay his“implausible” PCP:But the essential point of the philosophy was and is thatif the universe was evolving and changing, then there is no reason totrust what we call the laws of physics, established by experimentsperformed here and now, to have permanent validity. (Bondi 1990, p.192)Hence, or so Bondi's argument goes, since there is reasonnot to trust the laws of physics if the universe isevolving, let us presume that the universe is notevolving and changing; that is, let us presume PCP. Although theprinciple (and the theory which results from it—steady statecosmology) is, as McVittie remarked, “much more restrictive thangeneral relativity”; (McVittie 1990, p. 45) it is this veryrestrictiveness which satisfies Bondi's Popperian wishes: For the correct argument has always been that the steadystate model was the one that could be disproved most easily byobservation, Therefore, it should take precedence over other lessdisprovable ones until it has been disproved. (Bondi and Kilmister1959, p. 55-6)In another place, Bondi makes a similar point: “Comparison withobservation becomes then possible and renders the PCP liable toobservational disproof. This possibility of a clear-cut disproofestablishes the scientific status of PCP.” (Bondi 1957, p. 198)Comments such as this make clear Bondi's committment to a Popperianaddition to the basic deductive methodology he inherited from Milne. 8.5 A Popperian ConclusionIn the end, the philosophical purity of Bondi's steady state theoryserved him, and cosmology, well. Of course, the usual suspect, Dingle,and others of his ilk, such as McVittie in particular, were outraged,and loudly, at Bondi's extension of Milne's methods. A passage fromDingle's R.A.S. Presidential Address suffices to show the tenor of thedebate's declining days:Even idle speculation may not be quite valueless if it isrecognized for what it is. If the new cosmologists would observe thisproviso, calling a spade a spade and not a perfect agriculturalprinciple, one's only cause for regret would be that such great talentswere spent for so little profit. (Dingle 1953, p. 404)But PCP and the theory which it engendered were exactly asdescribed: eminently falsifiable. No matter the extent of Dingle etal's disdain, Steady State theory stayed right out in front, readyfor whatever empirical observations might be slung at it. As Bondi said“Show me some fossils from an evolving universe, and I'll give itup.” In 1965, the fossils arrived, courtesy of the observationsof the 3° K remnant microwave radiation.And Bondi, true to his philosophy, gave it up.BibliographyA.D.R. [initials of the semi-anonymous reviewer], 1938, “APhilosophy of Science,” Nature (London) 141: 95-96.Bondi, H., 1957, “Some Philosophical Problems inCosmology”, In British Philosophy in the Mid-Century.Edited by C. A. Mace. London: George Allen and Unwin.Bondi, H., 1960, Cosmology, 2 ed. Cambridge: CambridgeUniversity Press.Bondi, H., 1990, “The Cosmological Scene 1945-1952”, InModern Cosmology in Retrospect. Edited by B. Bertotti, etal. Cambridge: Cambridge University Press.Bondi, H. and C. W. Kilmister, 1959, “The Impact of Logikder Forschung,” Brit.J.Phil.Sci. 10: 55-57.Crowther, J. G. 1970, Fifty Years with Science, London:Barrie & Jenkins.deSitter, W., 1934, “On the Foundations of the theory ofRelativity, with Special reference to the Theory of the ExpandingUniverse,” Proceedings,Royal Academy Amsterdam 37:597-601.Dingle, H. 1931, The Evolution of the Universe, London:Nature.Dingle, H., 1933, “On E.A. Milne's theory of world structureand the expansion of the Universe,” Z.Astrophysik 6:173-179.Dingle, H., 1937, “Modern Aristotelianism,” Nature(London) 139: 784-786.Dingle, H., 1938, “Science and the Unobservable,”Nature (London) 141: 21-28.Dingle, H., 1953, “The President's Address,”Mon.Not.R .astron.Soc.: 113: 393-407.Eddington, A. S., 1932, The Expanding Universe, Ann Arbor:Ann Arbor Paperbacks-U.Mich Press.Eddington, A. S., 1935, “Review of Relativity Gravitationand World-Structure,” Nature (London) 135:635-636.Eddington, A. S. 1939, The Philosophy of Physical Science,New York: Macmillan .. Gale, G., Urani, J., 1994, “ Philosophical Midwifery andthe Birth Pangs of Modern Cosmology,” American Journal ofPhysics 61:66:73.Gale, G., Urani, J., 1999, “Milne, Bondi, and the‘Second Way’ to Cosmology,” in H. Goenner (ed.),The Expanding Worlds of General Relativity, Boston:Birkhauser, pp.343-77.Kermack, W. O. and W. H. McCrea, 1933, “On Milne's Theory ofWorld Structure,” Mon.Not.R.astron.Soc. 93:519-529.McCrea, W. H., 1935, “Observable Relations in relativisticCosmology,” Z.Astrophysik 9: 290-314.McCrea, W. H., 1939, “The Evolution of Theories of Space-Timeand Mechanics,” Phil.Sci. 6: 137-162.McVittie, G. C., 1931, “The Problem of n Bodies andthe Expansion of the Universe,” Mon.Not.R.astron.Soc.91: 274-283.McVittie, G. C., 1933a, “The Mass-particle in an ExpandingUniverse,” Mon.Not.R.astron.Soc. 93: 325-339.McVittie, G. C., 1933b, “Milne's Theory of the Expansion ofthe Universe,” Nature (London) 131: 533-534.McVittie, G. C., 1934, “The Spiral Nebulae and the Expansionof the Universe,” Phys.Soc.(Lond.)Reports 1: 24-29.McVittie, G.C., 1939, “Observation and Theory inCosmology,” Proc.Phys.Soc.Lond 51: 529-537.McVittie, G. C. 1990, Interview, 21 Mar 78, In Interviews withAstrophysicists, Edited by American Institute of Physics, NewYork: American Institute of Physics.Milne, E. A., 1929, The Aims of Mathematical Physics,Oxford: Oxford University Press.Milne, E. A., 1933, “World-structure and the Expansion of theUniverse,” Z.Astrophysik 6: 1-35.Milne, E. A., 1934a, “Some Points in the Philosophy ofPhysics: Time, Evolution and Creation,” Philos. 9:19-38.Milne, E. A., 1934b, “World-models and theWorld-picture,” Observatory, 57: 24-27.Milne, E. A. 1935, Relativity Gravitation andWorld-Structure. Oxford: Clarendon Press.Milne, E. A., 1937, “Kinematics, Dynamics, and the Scale ofTime,” Proc.Roy.Soc.(Lond.) A158: 324-329.Milne, E. A., 1943, “The Fundamental Concepts of NaturalPhilosophy,” ProcRoySoc(Edin) 63: 10-24.Milne, E. A., 1932-37, Correspondence with Geoffrey Milne. Thiscorrespondence is in Modern Manuscripts, Bodelian Library, Oxford, andis used with permission. .Robertson, H. P., 1933a, “On E.A. Milne's Theory of WorldStructure,” Z.Astrophysik 7: 152-162.Robertson, H. P., 1933b, “Relativistic Cosmology,”Rev.Mod.Phys. 5: 62-90.Robertson, H. P., 1935, “Kinematics andWorld-structure,” Ap.J. 82: 284-301.Robertson, H. P., 1936, “Review of Milne's RelativityGravitation and World-Structure,” Ap.J. 83:61-66.Temple, G., 1939, “Relativistic Cosmology,”PhysSoc.(London), 51: 465-478.Walker, A. G., 1934, “The Principle of Least Action inMilne's Kinematical Relativity,” Proc.Roy.Soc.(Lond.)147A: 478-490.Walker, A. G., 1935, “On the formal comparison of Milne'skinematical system with the systems of general relativity,”Mon.Not.R.Astr.Soc. 95: 263-269.Whittaker, E. T., 1935, “Review of Relativity Gravitationand World-Structure,” Observ. 58: 179-188.Whittaker, E. T., 1941, “Some Disputed Questions in thePhilosophy of the Physical Sciences,” ProcRoySoc(Edin)61: 160-175.Other Internet ResourcesAt this time there are few if any internet sites devoted to thehistory and philosophy of modern cosmology. What is typically availableis information relating to cosmology within the history of astronomy,or presentations about contemporary cosmology. The URLs given below arethe best sources for history of cosmology; there are no known sitesrelating to the philosophy of modern cosmology.The Shapley-Curtis Debate in 1920 (maintained byRobert J. Nemiroff, Michigan Technological University and NASAGoddard)History of Astronomy (maintained by Prof. Dr.Wolfgang Dick, Astronomische Institute, Universität Bonn)Cosmology Books and Links (compiled by Joseph S.Tenn, Physics and Astronomy, Sonoma State University)Cosmology Since 1900 (by Joseph S. Tenn, Physicsand Astronomy, Sonoma State University)Related Entries epistemology | general relativity: early philosophical interpretations of | induction: new problem of | induction: problem of | metaphysics | Popper, Karl | rationalism vs. empiricism | science, philosophy of | scientific method | space and time: inertial frames Copyright © 2007 byGeorge Gale<galeg@umkc.edu> |
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