 Friedman's interpretation (1992) of the Phenomenology deserves special mention. According to him, in light of Kant's rejection of Newton's absolute space and time, he must give an account of the concept of true motion – as change of true place over time – presupposed by classical mechanics. To this end, Kant “views the laws of motion as definitive or constitutive of the spatio-temporal framework of Newtonian theory,” hence these laws “count as a priori” for him (p. 143). The reason Kant takes them as constitutive is the following. In Kant's Phenomenology, the three Newtonian laws define a concept of true motion: the true motions of bodies just are those that obey the dynamical laws. Moreover, the concept must be given “objective meaning in experience,” viz. measured empirically. To do so, Kant views Newton's three laws as holding primarily in a privileged system of reference, namely the center-of-mass (CM) frame of the system of the world, which the CM-frame of our Solar System approximates to a very good degree. Thus, by measuring the motions of bodies relative to this frame, we produce objective experience of these motions. However, this frame must first be located. To do so, Kant thinks, we must likewise count the law of universal gravitation as a priori, not empirical-inductive. If we know a priori that all bodies in the Solar System necessarily attract each other, from their observable, mutually-induced accelerations we can infer their masses. In turn, knowing their masses will enable us to locate the CM-frame of the system. (In a system of bodies, the center of mass is the point relative to which the bodies' distances are in inverse proportion to their masses.) With respect to this distinguished frame, the motions of bodies count as their true motions, Friedman claims. Hence, immediate and essential gravitation “cannot be straightforwardly obtained from our experience of matter and its motions – by some sort of inductive argument, say” – because universal gravitation is “necessarily presupposed in making an objective experience of matter and its motions possible in the first place” (pp.  157–158). However, the CM-frame of the Solar System is just approximately an inertial frame. Scientific inquiry must ultimately look beyond it, to better and better approximations of an inertial frame. And, Kant's absolute space is just the concept that directs our search for such approximations. More recently, Friedman updated and expanded his interpretation in (2013). In view of recent scholarship, Friedman has now made a convincing case that it is Kant's laws of mechanics – not Newton's three laws, as claimed in (1992) – that define the privileged frame (Kantian absolute space) relative to which bodies have true motions, in the Phenomenology.  