Journal Article

A Puzzle about Laws, Symmetries and Measurability

John T. Roberts

in The British Journal for the Philosophy of Science

Published on behalf of British Society for the Philosophy of Science

Volume 59, issue 2, pages 143-168
Published in print June 2008 | ISSN: 0007-0882
Published online June 2008 | e-ISSN: 1464-3537 | DOI:
A Puzzle about Laws, Symmetries and Measurability

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I describe a problem about the relations among symmetries, laws and measurable quantities. I explain why several ways of trying to solve it will not work, and I sketch a solution that might work. I discuss this problem in the context of Newtonian theories, but it also arises for many other physical theories. The problem is that there are two ways of defining the space-time symmetries of a physical theory: as its dynamical symmetries or as its empirical symmetries. The two definitions are not equivalent, yet they pick out the same extension. This coincidence cries out for explanation, and it is not clear what the explanation could be.

The Puzzle: Symmetries, Measurability and Invariance

1.1 The symmetries and the measurable quantities of Newtonian mechanics

1.2 The puzzle

Two Easy Answers

Another Unsuccessful Solution: Appeal to Geometrical Symmetries

Locating the Puzzle

The Relation between Laws and Measurability

A Possible Solution

Journal Article.  12787 words. 

Subjects: Philosophy of Science ; Science and Mathematics

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