My philosophical work focuses on the epistemic status of empirical evidence in cosmology and astrophysics, with a particular focus on dark matter research. Due to the complexity of the evolution of the universe, and the exponential growth of cosmological and astrophysical observations throughout the 20th century, cosmology raises new questions about empirical evidence for philosophers of science. My work draws on and contributes to insights from general philosophy of science as well as to the nascent fields of philosophy of cosmology and astrophysics.

Evidence Generation: Cosmology as an Integrative Science​
I develop an account of cosmology as an integrative science by investigating the epistemic underpinnings of how empirical methods and lines of evidence can come to bear on cosmological model-building. The common challenges associated with integration are exacerbated in cosmology by the unknown nature of dark matter and dark energy, together 95% of the energy density of the universe. I highlight three challenges to successful integration in cosmology, and how cosmologists can respond to them.

1. How can existing experimental techniques responsibly be applied to genuinely novel physics? I argue that this sometimes requires substantive assumptions about the novel target. This 'method-driven logic' is different from how experiments are usually justified. 
2. Whether or not a line of evidence results from a method-driven experiment affects the warrant that this evidence can provide for conclusions about the target. I highlight an apparent paradox of success: while negative results allow for secure constraints on the theory of the target, the warrant from positive results is less clear. 
3. With accelerator experiments reaching their limits, particle physics has started to exploit the early universe as a new source of evidence. This is a substantive methodological shift. I am interested in what epistemic shift is associated with this methodological shift, if any. 

Evidence Evaluation: Anomalies on Galactic Scales
A second research area is centered on anomalies in cosmology. Anomalies present a recurring challenge for philosophers of science: when does an apparent discrepancy between a theoretical prediction and an empirical observation or between different empirical observations constitute a genuine anomaly (and thus a problem for the theory), and are there contexts where it can temporarily be ignored for the pursuit of other goals? Although many attempts have been made in the past, it seems impossible to formulate universally applicable necessary and sufficient conditions to distinguish the two situations above. Instead, I draw on the history of cosmological practice to make headway on the question of anomalies in context of cosmology and astrophysics.

1. In collaboration with Nora Boyd, I wrote a paper on the small-scale challenges for the cosmological concordance model. We argued that, right now, the small-scale challenges do not constitute genuine anomalies for ΛCDM. We further recommended prioritizing further developments of hydrodynamic simulations, based on the principle of epistemic conservatism and the need to identify contributing causal factors.
2. In an ongoing project with Richard Dawid, I examine how galactic scale phenomenology has been employed by critics of dark matter and ΛCDM, particularly adherents of MOND. We examine why the defense of MOND, over dark matter, fails, despite MONDs apparent success on galactic scales: we show that the only plausible reconstruction of the MOND defense is in terms of meta-empirical confirmation, but, insofar as the MONDian defense instantiates MEC, it does so in an unsatisfactory way.

History of relativistic cosmology: discussions at the BAAS
In collaboration with Mike Schneider
In September 1931, a peculiar event in the history of relativistic cosmology took place. At the Centenary Meeting of the British Association for the Advancement of Science (BAAS), a panel discussion was organized on “The Expanding Universe”. The recorded remarks and press reports of the meeting show a field where multiple foundational questions were far from being settled. We pursue a detailed study of the foundational debates taking place during the early days of the discipline we now call relativistic cosmology and emerging at the BAAS. A first paper focuses on de Sitter and Georges Lemaître’s diverging responses to the timescale problem, that is, that the evolving universe appeared to be younger than the oldest stars in the universe. We argue that their disagreement is symptomatic of an unsettled foundational question about what role considerations of scale should play in relativistic cosmology.

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A visual representation of ΛCDM, the standard model of cosmology. Image credit: ESA / The Planck Collaboration