Testability and viability: is inflationary cosmology “Scientific”?

Abstract

We provide a philosophical reconstruction and analysis of the debate on the scientific status of cosmic inflation that has played out in recent years. In a series of critical papers, Ijjas, Steinhardt, and Loeb have questioned the scientificality of current views on cosmic inflation. Proponents of cosmic inflation, such as Guth and Linde, have in turn defended the scientific credentials of their approach. We argue that, while this defense, narrowly construed, is successful against Ijjas, Steinhardt, and Loeb, the latters’ reasoning does point to a significant epistemic issue that arises with respect to inflationary theory. We claim that a broadening of the concept of theory assessment to include meta-empirical considerations is needed to address that issue in an adequate way.