Anastasiia Lazutkina

In this paper, the theoretical terms of contemporary cosmology are examined as intellectual artefacts. An ontology and methodology are introduced for this purpose, which includes defining the concept of a hypothetical object. Introducing a hypothetical object is contrasted with the modification of physical laws as alternative ways of explaining the discrepancy between observations and theoretical predictions. Historical examples of theory choice, which involved these alternatives, are discussed. This is followed by a study of theory choice in contemporary cosmology. In particular, the focus is on the case of dark matter and modified gravity as alternative explanations for observed mass discrepancies in galaxies and galaxy clusters. These alternatives are analyzed, and their similarities and differences to the historical examples are pointed out.

In this chapter I will discuss Karl Popper’s notion of metaphysical research programmes (MRPs) and apply it to contemporary cosmology. While Popper was extremely critical of Big Bang cosmology, his work on MRPs provides a potentially fruitful way of understanding the discipline in a different light. I will suggest that while cosmology does fail to meet the criteria Popper sets for a mature science, the standard model of cosmology (also known as ΛCDM) could be seen as an example of a MRP. I will examine the Cosmological Principle as well as the dark matter hypothesis as prospective parts of this MRP. Finally, I will go beyond Popper’s own views and evaluate ΛCDM and its main rival, Modified Newtonian Dynamics (MOND), with the help of two methodological tools: the correspondence principle as formally explicated by E. K. Voishvillo, and Ilkka Niiniluoto’s measures of truthlikeness. The conclusion I will draw from this is that MOND is a viable and in some respects superior alternative to ΛCDM.