While $$\Lambda $$ Λ CDM has emerged as the standard model of cosmology, a small group of physicists defends modified newtonian dynamics (MOND) as an alternative view on cosmology. Exponents of MOND have employed a broad, at times explicitly philosophical, conceptual perspective in arguing their case. This paper offers reasons why that MONDian defense has been ineffective. First, we argue that the defense is ineffective according to Popperian or Lakatosian views–ostensibly the preferred philosophical views on theory assessment of proponents of (...) MOND. Second, we argue that the defense of MOND can instead best be reconstructed as an instance of meta-empirical theory assessment. The formal employment of meta-empirical assessment by MONDians is unconvincing, however, because it lacks a sufficient epistemic foundation. Specifically, the MONDian No Alternatives Argument relies on falsifiability or explanation conditions that lack epistemic relevance, while the argument from Unexpected Explanatory Success fails since there is a known alternative to MOND. In the last part of the paper, we draw some lessons for applications of meta-empirical assessment more generally. (shrink)

Peter Kosso discusses the weak gravitational lensing observations of the Bullet Cluster and argues that dark matter can be detected in this system solely through the equivalence principle without the need to specify a full theory of gravity. This paper argues that Kosso gets some of the details wrong in his analysis of the implications of the Bullet Cluster observations for the Dark Matter Double Bind and the possibility of constructing robust tests of theories of gravity at galactic and greater (...) scales. Even the Bullet Cluster evidence is not sufficiently detailed to allow precision tests of General Relativity that would distinguish it from its rivals at galactic and greater scales. Taking into account the total evidence available, we cannot rule out “ugly” solutions to the dynamical discrepancy in astrophysics that involve both a large quantity of dark matter and a theory of gravity whose predictions differ significantly from those of General Relativity for interactions taking place at galactic and greater scales. (shrink)

Baker argues that quantitative parsimony—the principle that hypotheses requiring fewer entities are to be preferred over their empirically equivalent rivals—is a rational methodological criterion because it maximizes explanatory power. Baker lends plausibility to his account by confronting it with the example of postulating of the neutrino in order to resolve a discrepancy in Beta decay experiments. Baker’s account is initially attractive, but I argue that its details are problematic and that it yields undesirable consequences when applied to the case of (...) astrophysical dark matter. Baker has not succeeded in showing why quantitative parsimony is a theoretical virtue. (shrink)