Please email me for a copy of any of the papers below in case you don’t have access to the respective journal.

Papers in peer-reviewed journals

A common adage runs that, given a theory manifesting symmetries, the syntax of that theory should be modified in order to construct a new theory, from which symmetry-variant structure of the original theory has been excised. Call this strategy for explicating the underlying ontology of symmetry-related models reduction. Recently, Dewar has proposed an alternative to reduction as a means of articulating the ontology of symmetry-related models—what he calls (external) sophistication, in which the semantics of the original theory is modified, and symmetry-related models of that theory are treated as if they are isomorphic. In this paper, we undertake a critical evaluation of sophistication about symmetries—we find the programme underdeveloped in a number of regards. In addition, we clarify the interplay between sophistication about symmetries, and a separate debate to which Dewar has contributed—viz., that between interpretational versus motivational approaches to symmetry transformations.

Absolutism about mass within Newtonian Gravity claims that mass ratios obtain in virtue of absolute masses. Comparativism denies this. Defenders of comparativism promise to recover all the empirical and theoretical virtues of absolutism, but at a lower ‘metaphysical cost’. This paper develops a Machian form of comparativism about mass in Newtonian Gravity, obtained by replacing Newton’s constant in the law of Universal Gravitation by another constant divided by the sum over all masses. Although this form of comparativism is indeed empirically equivalent to the absolutist version of Newtonian Gravity—thereby meeting the challenge posed by the comparativist’s bucket argument—it is argued that the explanatory power and metaphysical parsimony of comparativism (and especially its Machian form) are highly questionable.

  • Martens, N.C.M. (2019), “The Metaphysics of Emergent Spacetime Theories”, Philosophy Compass 14(7) e12596 [ Published version (Paywall) ]

The debate concerning the ontological status of spacetime is standardly construed as a dilemma between substantivalism and relationalism. I argue that a trilemma is more appropriate, emergent spacetime theories being the third category. Traditional philosophical arguments do not distinguish between emergent spacetime and substantivalism. It is arguments from physics that suggest giving up substantivalism in favour of emergent spacetime theories. The remaining new dilemma is between emergent spacetime and relationalism. I provide a list of questions which one should consider when discussing emergent spacetime theories and apply them to a quantum superfluid toy model of emergent spacetime.

Absolutism about mass claims that mass ratios obtain in virtue of absolute masses. Comparativism denies this. Dasgupta (2013) argues for comparativism about mass, in the context of Newtonian Gravity. Such an argument requires proving that comparativism is empirically adequate. Dasgupta equates this to showing that absolute masses are undetectable, and attempts to do so. This paper develops an argument by Baker to the contrary: absolute masses are in fact empirically meaningful, that is detectable (in some weak sense). Additionally, it is argued that the requirement of empirical adequacy should not be cashed out in terms of undetectability in the first place. The paper closes by sketching the possible strategies that remain for the comparativist. Along the way a framework is developed that is useful for thinking about these issues: Ozma games—how could one explain to an alien civilisation what an absolute mass is?

Laplace wondered about the minimal choice of initial variables and parameters corresponding to a well-posed initial value problem. Discussions of Laplace’s problem in the literature have focused on choosing between spatiotemporal variables relative to absolute space (i.e. substantivalism) or merely relative to other material bodies (i.e. relationalism) and between absolute masses (i.e. absolutism) or merely mass ratios (i.e. comparativism). This paper extends these discussions of Laplace’s problem, in the context of Newtonian Gravity, by asking whether mass needs to be included in the initial state at all, or whether a purely spatiotemporal initial state suffices. It is argued that mass indeed needs to be included; removing mass from the initial state drastically reduces the predictive and explanatory power of Newtonian Gravity.

  • Martens, N.C.M. (2017), “Regularity Comparativism about Mass in Newtonian Gravity”, Philosophy of Science 84(5): 1226-1238 [ Postprint | Published Version ]

Comparativism—the view that mass ratios are not grounded in absolute masses—faces a challenge by Baker which suggests that absolute masses are empirically meaningful. Regularity comparativism uses a liberalised version of the Mill-Ramsey-Lewis Best Systems Account to have both the Laws of Newtonian Gravity and the absolute mass scale supervene on a comparativist Humean mosaic as a package deal. I discuss three objections to this view, and conclude that it is untenable. The most severe problem is that once we have reduced away the absolute masses, there is nothing that stops us from also reducing the mass ratios.

Special issues (Editor)

Conference proceedings (peer-reviewed)

Conference reports

  • Chall, C. & Martens, N.C.M. (2020), “Simplicity in the Sciences and Humanities: Report on the Bonn “Simplicities and Complexities” Conference”, forthcoming in Journal for General Philosophy of Science [ Published version (open access) ]

Work in progress

  • Dark Matter = Modified Gravity? Scrutinising the spacetime-matter distinction via the modified gravity/ dark matter lens, with Dennis Lehmkuhl, draft available upon request
  • A roadmap to interpreting fields that are both (dark) matter and (an aspect of) spacetime, with Dennis Lehmkuhl, draft available upon request
  • The Aharonov-Bohm Effect as a Case Study for Motivational Realism
  • Dark Matter Realism
  • Explanatory power of Dark Matter vs Modified Gravity
  • The Trading Zone between Dark Matter and Modified Gravity