Marius Stan

Newton's Principia begins with eight formal definitions and a scholium, the so-called scholium on space and time. Despite a history of misinterpretation, scholars now largely agree that the purpose of the scholium is to establish and defend the de fi nitions of key concepts. There is no consensus, however, on how those definitions differ in kind from the Principia's formal definitions and why they are set-off in a scholium. The purpose of the present essay is to shed light on the scholium by focusing on Newton's notion and use of de fi nition. The resulting view is developmental. I argue that when Newton first wrote the Principia, he viewed the scholium's definitions as items of “natural philosophy.” By the time of the third edition, however, he came to view their methodological status differently; he viewed them as belonging to the more qualified “manner of geometers.” I explicate the two methods of natural inquiry and draw out their implications for Newton's account of space.

Kant's Metaphysical Foundations of Natural Science is one of the most difficult but also most important of Kant's works. Published in 1786 between the first and second editions of the Critique of Pure Reason, the Metaphysical Foundations occupies a central place in the development of Kant's philosophy, but has so far attracted relatively little attention compared with other works of Kant's critical period. Michael Friedman's book develops a new and complete reading of this work and reconstructs Kant's main argument clearly and in great detail, explaining its relationship to both Newton's Principia and eighteenth-century scientific thinkers such as Euler and Lambert. By situating Kant's text relative to his pre-critical writings on metaphysics and natural philosophy and, in particular, to the changes Kant made in the second edition of the Critique, Friedman articulates a radically new perspective on the meaning and development of the critical philosophy as a whole.

We examine the contrast between the “Newtonian style” and the Cartesian, hypothetico-deductive method in order to expand on George Smith's account of working hypotheses and theory-mediation. We stress the pivotal role of theory-mediation in turning experience into well-defined phenomena and introduce the complementary notions of conditional and independent evidence. Conditional evidence is evidence in favor of an hypothesis that is based on phenomena that would not be constituted as phenomena without the hypothesis in question. Direct evidence is evidence based on phenomena that are independently available. We use the distinction to interrogate the role of mathematical representation as the most basic constitutive posit of the Newtonian style, as the working hypothesis that enables all further theory-mediation. Our primary examples are Newton's struggles with motion in fluids and his defense of the Laws of Motion.

I argue that Isaac Newton's De Gravitatione should not be considered an authoritative expression of his thought about the metaphysics of space and its relation to physical inquiry. I establish the following narrative: In De Gravitatione (circa 1668–84), Newton claimed he had direct experimental evidence for the work's central thesis: that space had "its own manner of existing" as an affection or emanative effect. In the 1710s, however, through the prodding of Roger Cotes and G. W. Leibniz, he came to see that this evidence relied on assumptions that his own Principia rendered unjustifiable. Consequently, he (i) revised the conclusions he explicitly drew from the experimental evidence, (ii) rejected the idea that his spatial metaphysics was grounded in experimental evidence, and (iii) reassessed the epistemic status of key concepts in his metaphysics and natural philosophy. The narrative I explore shows not only that De Gravitatione did not constitute the metaphysical backdrop of the Principia as Newton ultimately understood it, but that it was the Principia itself that ultimately lead to the demise of key elements of De Gravitatione. I explore the implications of this narrative for Andrew Janiak's and Howards Stein's interpretations of Newton's metaphysics.

We argue that a conflict between two conceptions of “quantity of matter” employed in a corollary to proposition 6 of Book III of the Principia illustrates a deeper conflict between Newton’s view of the nature of extended bodies and the concept of mass appropriate for the theoretical framework of the Principia. We trace Newton’s failure to recognize the conflict to the fact that he allowed for the justification of natural philosophical claims by two types of a posteriori, empiricist methodologies. Newton's thoughts on these methodologies demonstrate that his natural philosophy continued to develop after the publication of the first edition of Principia and that De Grav should be understood as an early, and not necessarily representative, text.

In his Metaphysische Anfangsgründe der Naturwissenschaft, Kant claims that chemistry is a science, but not a proper science (like physics), because it does not adequately allow for the application of mathematics to its objects. This paper argues that the application of mathematics to a proper science is best thought of as depending upon a coordination between mathematically constructible concepts and those of the science. In physics, the proper science that exhausts the a priori knowledge of objects of the outer sense, only motions and concepts reducible to motions can be legitimately coordinated with mathematical constructions. Since chemistry can neither achieve its own a priori principles of coordination nor be reduced to the coordinated doctrine of motion, it is a merely improper science.

Kant’s denial that psychology is a properly so-called natural science, owing to the lack of application of mathematics to inner sense, has garnered a great deal of attention from scholars. Although the interpretations of this claim are diverse, commentators by and large fail to ground their views on an account of Kant’s conception of applied mathematics. In this article, I develop such an account, according to which the application of mathematics to a natural science requires both a mathematical representation and a metaphysical validation for the positive use of this representation to achieve a priori knowledge about nature. The second condition—that of metaphysical validation—has been overlooked in the literature. I show that psychology’s falling short of natural scientific propriety consists not in our lacking sufficient mathematical tools for the representation of inner states, according to Kant. After all, we can represent the mere temporality of inner states with the line and their intensities with numbers. Rather, the problem is that metaphysics does not validate the further use of such mathematical entities for the achievement of a priori knowledge about inner phenomena.

Kant’s preoccupation with architectonics is a characteristic and noteworthy aspect of his thought. Various features of Kant’s argumentation and philosophical system are founded on the precise definitions of the various subdomains of human knowledge and the derivative borders among them. One science conspicuously absent from Kant’s routine discussions of the organization of knowledge is chemistry. Whereas sciences such as physics, psychology, and anthropology are all explicitly located in the architectonic, chemistry finds no such place. In this paper, I examine neglected passages from Kant’s corpus as well as texts regarding chemistry that Kant himself read in order to unveil his views on the definition of chemistry and its relations with the other sciences. These considerations reveal chemistry to be the science that studies the changes of matter into new kinds. Yet Kant idiosyncratically believes that such a change requires an infinite division of matter, effected by chemical forces. Although this understanding of chemical change dovetails with Kant’s dynamical, continualist theory of matter, it implies that chemistry cannot be reduced to physics. Thus, although chemistry stands alongside empirical physics as an applied natural science in Kant’s architectonic, it remains a distinct, independent science.

A popular method for comparing the structures of mathematical objects, which I call the ‘subset approach’, says that X has more structure than Y just in case X’s automorphisms form a proper subset of Y’s automorphisms. This approach is attractive, in part, because it seems to yield the right results in some comparisons of spacetime structure. But as I show, it yields the wrong results in a number of other cases. The problem is that the subset approach compares structure using automorphism sets. So a different approach is needed: structure should be compared using automorphism groups.

At the time of Heinrich Hertz's premature death in 1894, he was regarded as one of the leading scientists of his generation. However, the posthumous publication of his treatise in the foundations of physics, "Principles of Mechanics", presents a curious historical situation. Although Hertz's book was widely praised and admired, it was also met with a general sense of dissatisfaction. Almost all of Hertz's contemporaries criticized "Principles" for the lack of any plausible way to construct a mechanism from the hidden masses that are particularly characteristic of Hertz's framework. This issue seemed especially glaring given the expectation that Hertz's work might lead to a model of the underlying workings of the ether. In this paper I seek an explanation for why Hertz seemed so unperturbed by the difficulties of constructing such a mechanism. In arriving at this explanation, I explore how the development of Hertz's image-theory of representation framed the project of "Principles". The image-theory brings with it an austere view of the essential content of mechanics, only requiring a kind of structural isomorphism between symbolic representations and target phenomena. I argue that bringing this into view makes clear why Hertz felt no need to work out the kinds of mechanisms that many of his readers looked for. Furthermore, I argue that a crucial role of Hertz's hypothesis of hidden masses has been widely overlooked. Far from acting as a proposal for the underlying structure of the ether, I show that Hertz's hypothesis ruled out knowledge of such underlying structure.

The standard view is that the Lagrangian and Hamiltonian formulations of classical mechanics are theoretically equivalent. Jill North, however, argues that they are not. In particular, she argues that the state-space of Hamiltonian mechanics has less structure than the state-space of Lagrangian mechanics. I will isolate two arguments that North puts forward for this conclusion and argue that neither yet succeeds. 1 Introduction2 Hamiltonian State-space Has less Structure than Lagrangian State-space2.1 Lagrangian state-space is metrical2.2 Hamiltonian state-space is symplectic2.3 Metric > symplectic3 Hamiltonian State-space Does Not Have Less Structure than Lagrangian State-space3.1 Lagrangian state-space has less than metric structure3.1.1 A potential worry3.1.2 General Lagrangians3.2 Hamiltonian state-space has more than symplectic structure3.2.1 A dual structure on the Hamiltonian state-space3.2.2 Simple Hamiltonians3.3 Comparing Lagrangian and Hamiltonian structures3.3.1 Counting mathematical structure3.3.2 Symplectic and metric structure are incomparable4 An Alternative Argument for LS4.1 The argument for P3*4.2 Symplectic manifold vs. tangent bundle structure4.3 Trying to patch up the argument for P3*5 Interpreting Mathematical Structure5.1 State-space realism5.2 Model isomorphism and theoretical equivalence6 Conclusion.

In this article, I examine whether or not the Hamiltonian and Lagrangian formulations of classical mechanics are equivalent theories. I do so by applying a standard for equivalence that was recently introduced into philosophy of science by Halvorson and Weatherall. This case study yields three general philosophical payoffs. The first concerns what a theory is, while the second and third concern how we should interpret what our physical theories say about the world. 1Introduction 2When Are Two Theories Equivalent? 3Preliminaries on Classical Mechanics 3.1Hamiltonian mechanics 3.2Lagrangian mechanics 4Are Hamiltonian and Lagrangian Mechanics Equivalent Theories? 4.1Tangent bundle versus cotangent bundle 4.2Tangent bundle versus symplectic manifold 4.3Lagrangian vector field versus Hamiltonian vector field 5Conclusion Appendix.