Relativity: The Theory and Its Philosophy

Relativity: The Theory and Its Philosophy

Author	Roger B Angel
Published	1980
Publisher	Pergamon Press
Pages	xi + 259
ISBN	0080251978

Relativity: The Theory and Its Philosophy is a 1980 book by the Canadian philosopher of science Roger B Angel, published by Pergamon Press in the Foundations & Philosophy of Science & Technology series under the general editorship of Mario Bunge. It is a self-contained treatment of the philosophical foundations of special and general relativity, complete with a compressed course in the mathematics required to follow the argument, from elementary trigonometry to the classical tensor calculus.

It is worth being clear at the outset about what this book is, because its title and its presence in this catalogue can both mislead. It is a defence of relativity, not a criticism of it — a work of mainstream philosophy of science in the scientific-realist tradition of Angel's teacher Mario Bunge. Its polemical energy is directed not at Einstein but at other philosophers: at Adolf Grünbaum's conventionalism, at Kuhn's and Feyerabend's incommensurability, and at the operationalism of Bridgman and the a priorism of Eddington.

Angel was candid about the mixture. "The purpose of a textbook is to open intellectual doors," he wrote in the preface — before adding that "I, too, have axes to grind."

Argument

Against the conventionality of simultaneity

The longest sustained argument in the book is against the thesis, associated with Reichenbach and developed at length by Grünbaum, that the one-way speed of light — and therefore distant simultaneity — is a matter of convention rather than of fact.

Angel's objection is that the thesis is either trivial or covertly verificationist. He asks whether it is "not strange, therefore, that he should put the alleged conventionality of one-way light velocities on all fours with the trivial type of convention involved in the choice of units", and argues that Grünbaum's position depends on the view "that the content of a theory is exhausted by its empirical consequences" — a doctrine Grünbaum elsewhere explicitly rejects. He presses the point that Grünbaum "seems to classify as conventional any item which is not empirically determined", which if correct makes it hard to accept the claim that the conventionality thesis is non-trivial.

Against the ε-generalised formulations of special relativity developed by Winnie and others, Angel argues that abandoning standard synchrony carries a cost usually left unstated: "if we abandon standard synchrony we must also abandon reciprocity" — the mutual symmetry of the relation between two frames in relative motion. He also argues, as a matter of exegesis, that the conventionality thesis is not to be found in Einstein's 1905 paper at all, since Einstein presents his stipulation as leading to "the factual consequence that the relationship of simultaneity is transitive".

This places Angel on the anti-conventionalist side of one of the central debates in twentieth-century philosophy of physics, alongside David Malament, whose 1977 result he cites approvingly. It is worth noting for readers of this wiki that the conventionality question is genuinely open in the philosophical literature and is taken seriously on both sides; W. Farrell Edwards's 1963 transformation, catalogued here, works the opposite side of the same street.

Against incommensurability

Chapter 6 responds directly to Thomas Kuhn and Paul Feyerabend on the incommensurability of successive scientific theories, and it does so in defence of scientific realism.

Angel concedes more than one might expect. He accepts that "Feyerabend correctly claims that the symbol 'm' which occurs in classical mechanics should not be identified with its counterpart which refers to relativistic mass", and agrees that classical and relativistic mechanics are better treated as distinct theories than as one reducible to the other. What he denies is the conclusion drawn from this. To say two theories are literally incommensurable is, he writes, an "astonishingly strong" claim, for "if two theories are literally incommensurable, it makes no sense to regard them as agreeing in respect to any empirical data". His own verdict is that the two mechanics stand "in the relationship of contrariety" — genuine rivals, and therefore decidable between "on the basis of experiment".

General covariance: half a concession to Kretschmann

The most delicate chapter concerns the principle of general covariance and Erich Kretschmann's celebrated objection that it is physically empty, since any theory — Newtonian mechanics included — can be written in generally covariant form.

Angel sets out two rival responses: J. L. Anderson's argument that covariance principles do have factual content, resting on the distinction between absolute and dynamical objects, and Bunge's argument that all covariance principles are devoid of factual content. He then takes a position that agrees with neither wholly. He accepts that general covariance is metatheoretical rather than factual — conceding Kretschmann's point — but rejects his own teacher's further step of identifying general covariance with general relativity, writing that Bunge "asserts, we believe erroneously, the equation: 'general covariance = general relativity'".

Presented with the dilemma that either covariance is factual or the relativity principle is empty, Angel replies: "we accept neither horn of this dilemma." His conclusion is that "covariance is neither necessary nor sufficient for the principle of general relativity" — the principle survives as a separate and contentful claim, even though, he adds, "Einstein sought to justify it on the basis of an incorrect heuristic argument".

This chapter is the one place where a critic of relativity might quote Angel as conceding that general covariance is vacuous. The concession is real, but the conclusion drawn from it is the opposite of a criticism of general relativity.

The clock paradox

Angel treats time dilation as physically real rather than apparent, and rejects both of the escape routes most often taken in the dissident literature. The first — "that since special relativity yields a contradiction, it is simply a false theory that one would do well to abandon" — he dismisses as radical; of the second, the neo-Lorentzian reinstatement of the aether to supply "a genuine asymmetry between the two brothers, which derives from their being in different states of motion relative to the aether", he writes that it "amounts to both praising and violating the theory at the same time".

His own resolution is the standard one: the travelling twin changes inertial frames, and in the general-relativistic setting the geodesic is a maximum interval.

Reception

The book has been cited steadily if modestly for four decades — on the order of two dozen citations — and is generally used as a clear secondary exposition rather than as a canonical source. The most substantial engagements are A. A. Ungar's 1986 paper in Philosophy of Science, which takes up Angel's argument that non-standard synchrony destroys reciprocity and expressly contrasts his position with Roberto Torretti's, and Peter Havas's 1987 paper in General Relativity and Gravitation on simultaneity, conventionalism and general covariance. Harvey Brown and Roland Sypel cite it in their 1995 work on the meaning of the relativity principle.

No review in a philosophy-of-science journal has been located, though the negative result rests on partial indexing of early-1980s book reviews and should not be taken as settled.

Why it appears on this wiki

The honest answer is that it appears here because it is a book about relativity. The page's original description was the Pergamon jacket copy, and the author page carried nothing but an institutional affiliation — the signature of a bulk metadata import rather than of a considered inclusion. Angel has no heterodox thesis about relativity and no connection to the dissident community.

There is nonetheless one genuine point of contact, and it is instructive. In The Ideology of Relativity: The Case of the Clock Paradox, catalogued on this wiki, Peter Hayes cites Angel twice — precisely because he is an orthodox defender of relativity who nonetheless treats the clock paradox as a problem still requiring resolution, and who offers his own account of how to clear it up. Angel is cited there as a hostile witness rather than as an ally: the argument is that even sympathisers concede the paradox has remained contested for a century.

Readers using this wiki to build a case against relativity should therefore treat this book as an opponent's statement of the strongest version of the orthodox position — which is, for that purpose, considerably more useful than another book agreeing with them.

Contents

1. Mathematical Preliminaries
2. Relativity and Newtonian Mechanics
3. The Principle of Special Relativity
4. Empiricism, Rationalism and Special Relativity
5. Special Relativity and Conventionalism
6. The Commensurability of Classical and Relativistic Mechanics
7. More Mathematics
8. The Path to General Relativity
9. An Outline of General Relativity
10. Relativity and Covariance
11. Spacetime and Geometry

Publication details

• Pergamon Press, Oxford, 1980; Foundations & Philosophy of Science & Technology series, general editor Mario Bunge; Pergamon International Library.
• xi + 259 pp. ISBN 0-08-025197-8 (hardcover), 0-08-025196-X (flexicover).
• Reissued by Elsevier in 2014 as a print-on-demand and electronic edition.
• The preface is dated Montreal, June 1979.

Note on dating: this page previously gave "1972 / 1980". There was no 1972 edition — the book's own copyright page reads "First edition 1980". The spurious date appears to come from a faulty Open Library record, and may have been reinforced by Angel's separate 1973 chapter "Relativity and Covariance" in Bunge's The Methodological Unity of Science.

See also

• Roger B Angel
• Special Relativity
• General Relativity
• Twin Paradox
• Adolf Grünbaum
• The Ideology of Relativity: The Case of the Clock Paradox

Links to Purchase Book

• Relativity: The Theory and Its Philosophy at Amazon.

External links

• Full text at the Internet Archive (borrowable).
• Publisher's page at Elsevier.