## Notes to Structuralism in Physics

1.
Einstein's
resolution of this conundrum is celebrated. He took the practical
indistinguishability to betoken a deeper identity and, in his Principle
of Equivalence, asserted that the two cases are the same. In effect
acceleration produces a gravitational field. The theoretical
underdetermination is eliminated by declaring that the inertial force
*-m A* is really a gravitational force after
all. The two

*T*-theoretical terms are really just the same; and an inertial system with a homogeneous gravitational field just is the same thing as a uniformly accelerated system without a gravitational field.