I begin by developing my conception of the (causal) necessity of genuine laws of nature in a new way. In particular, by emphasizing Kant’s distinction between proper and pure natural science in the Preface to the Metaphysical Foundations of Natural Science, I further explain the sense in which empirical laws of nature like the law of universal gravitation are nonetheless (causally) necessary, and, at the same time, I explain how the synthetic a priori laws of pure natural science acquire their special status in virtue of the way in which they are the conditions for making such (causally) necessary empirical laws possible in the first place. This depends on the characteristic way in which both mathematics and the special metaphysics of (physical) nature—through mathematically precise realization of the categories of substance and causality—work together in pure natural science. It turns out, in particular, that the fundamental Newtonian concepts of quantity of matter and (impressed) force—which are developed non-hypothetically as quantitative mathematical concepts—provide Kant with his basis for explaining how empirical causal laws (governing specifically Newtonian forces) can similarly be established non-hypothetically by what Newton calls “deductions from phenomena.” This emphasis on the Newtonian concept of force as a basis for establishing necessary causal relations non-hypothetically (in contrast to the mechanical natural philosophy that Newton is attempting to replace) then help to further explicate the special status of physical laws in the critical system. In particular, it further explains the sense in which the mechanical perspective on nature, as discussed in the Critique of the Power of Judgement, is privileged over the teleological perspective, and it therefore explains the sense in which there are no characteristically biological causal laws in the critical system. For in the teleological approach to nature the Newtonian mathematical concept of force is simply not applicable. Finally, this new approach, emphasizing the essentially non-hypothetical character of genuine causal laws of nature, also helps us to understand how Kant’s conception of causal necessity can still be maintained in post-Kantian physical science, so long as something like the characteristically mathematical conception of force and physical law first developed by Newton in the context of his particular formulation of mechanics is still maintained in later formulations—including in relativistic and quantum mechanics.