Schlick applied these insights to the fact that no physical means suffice to distinguish inertial frames or, in other words, no (uniform, rectilinear) motion can be detected relative to the ether. There are two alternative responses to this situation. The first alternative, due to Lorentz and Fitzgerald, accommodates experimental findings through the postulation of compensating contractions of moving bodies in the direction of motion. Buttressed by additional auxiliary hypotheses, the Lorentz-Fi