 This episode can be viewed as the replacement of an empirically adequate theory (the Lorentz-Poincaré theory) by a more ontologically parsimonious alternative (Special Relativity). Hence it is often taken to be an example of Occam’s Razor in action. The problem with using this example as evidence for Occam’s Razor is that Special Relativity (SR) has several other theoretical advantages over the Lorentz-Poincaré (LP) theory in addition to being more ontologically parsimonious. Firstly, SR is a simpler and more unified theory than LP, since in order to ‘save the phenomena’ a number of ad hoc and physically unmotivated patches had been added to LP. Secondly, LP raises doubts about the physical meaning of distance measurements. According to LP, a rod moving with velocity, \(v\), contracts by a factor of \((1 - v^2 /c^2)^{1/2}\). Thus only distance measurements that are made in a frame at rest relative to the ether are valid without modification by a correction factor. However, LP also implies that motion relative to the ether is in principle undetectable. So how is distance to be measured? In other words, the issue here is complicated by the fact that—according to LP—the ether is not just an extra piece of ontology but an undetectable extra piece. Given these advantages of SR over LP, it seems clear that the ether example is not merely a case of ontological parsimony making up for an otherwise inferior theory.