Revisiting the scientific nature of multiverse theories

Some scientists or philosophers argue that multiverse theories are unfalsifiable and thus not scientific. However, some advocates of multiverse theories have recently argued that although the multiverse is not observable, multiverse theories are indeed falsifiable in principle. Therefore, they share similar features with a conventional scientific theory. On the other hand, the proposals of an epistemic shift and nonempirical theory assessment have possibly revived the discussions of the scientific nature of multiverse theories. In this article, I revisit the falsifiable arguments made by the advocates of multiverse theories and show that these arguments do not justify arguing the scientific nature of such theories. Moreover, even if we accept the proposals of the epistemic shift and the nonempirical theory assessment, I argue that multiverse theories still cannot pass or satisfy the required assessments based on the new theoretical virtues and the nonempirical arguments. Copyright © 2023 The Author(s), under exclusive licence to Springer Nature B.V.