Events

The Approximate Cosmological Principle and Permanent Underdetermination in Cosmology

In this talk, I will discuss the implications of some recent work in observational cosmology and mathematical general relativity (GR) for the epistemology of spacetime. My primary aim is to articulate a non-trivial and physically relevant underdetermination thesis concerning the global, topological structure of models of GR. I will argue that my thesis is philosophically interesting for at least two reasons: (i) it affects “sensible realists,” viz., those who counsel realism only about theoretical claims that are amenable to empirical investigation (Stanford 2006); and (ii) it is “permanent” (in the sense of Pitts 2011). In order to formulate my thesis and to defend my claims, I begin by surveying cosmological research devoted to empirically determining the spatial topology of the universe (e.g., Akrami et al. 2024). This research typically assumes the Cosmological Principle (CP); however, CP is a very strong constraint on our theorizing, and its justification is fraught with difficulties. Indeed, strictly speaking, it is known not to hold, even in the observable universe. As such, it has been suggested that a more accurate reflection of our observational situation would be to assume an “approximate” CP. Drawing on recent mathematical work, I discuss one possible way of making this notion precise (Ringström 2013). Interestingly, when we pass to Ringström’s approximate CP, it appears that one cannot draw any conclusions about the topology of space. I carefully analyze why this occurs, and demonstrate that the resulting underdetermination is permanent. Time permitting, I compare my thesis to related results and sketch how my discussion can serve as a powerful starting point for anti-realist positions in the epistemology of spacetime.

Monday, October 19, 2026 9:30 AM

Inperson
Speaker will be in person – BHI Conference Room

Virtual
Zoom