 Moreover, Kant has no qualms at all about action at a distance, and he even attempts to demonstrate a priori (in the Metaphysical Foundations) that universal gravitation, as a manifestation of what he calls the “original” or “fundamental” force of attraction, must be conceived as an immediate action at a distance through empty  space.[31]  Kant also attempts to demonstrate his three “laws of mechanics” corresponding to Newton’s three laws of motion as synthetic a priori truths, especially the crucially important third law (the equality of action and  reaction).[32]  Whereas Newton had devoted considerable effort to producing experimental evidence for this law (see  note 14  above), Kant here ventures a rare criticism of Newton for not having the courage to prove it a  priori.[33]  Indeed, regarding this particular law as a synthetic a priori truth is central to Kant’s reinterpretation of the Newtonian concepts of (absolute) space, time, and motion; for it is in virtue of his understanding of the equality of action and reaction that Kant is now able simply to define the center of gravity of the solar system (in which this principle necessarily holds) as an empirically determinable (provisional) surrogate for Newtonian absolute  space.[34]  Moreover, and for closely related reasons, Kant takes the universality of what he calls the “original” or “fundamental” force of attraction—that it proceeds from every part of matter to every other part to infinity—as another synthetic a priori truth demonstrable in “pure natural  science”.[35]