The empirical content of the modern definition of relativity given in the Andersonian approach to spacetime theory has been overestimated. It does not imply the empirical relativity Galileo illustrated in his famous ship thought experiment. I offer a number of arguments—some of which are in essential agreement with a recent analysis of Brown and Sypel [1995]—which make this plausible. Then I go on to present example spacetime theories which are modern relativistic but violate Galileo's relativity. I end by briefly discussing (...) the prospects for improving on modern relativity. (shrink)

A class of theories which satisfy the Relativity Principle has been overlooked. The kinematics for these theories is derived by relaxing the 'boost isotropy' symmetry normally invoked, and the role the dynamical fields play in determining the inertial coordinate systems is emphasised, leading to a criticism of Friedman's (1983) practice of identifying them via the absolute objects of a spacetime theory alone. Some theories complete with 'boost anisotropic' dynamics are given.