This paper examines Plato’s hesitation in the Timaeus concerning the number of worlds—whether the cosmos is unique, multiple, or even quintuple—and focuses on the argument traditionally invoked to justify cosmic uniqueness. After reconstructing the so-called Argument from the Uniqueness of the Model (AUM), the paper shows that the singularity of the intelligible Model (the Form of the Living Being) can indeed be established without appeal to an infinite regress, on the basis of its required completeness. However, the further inference that the sensible cosmos must itself be unique proves more problematic.
By distinguishing between eidetic properties proper to Forms and the essential properties that can be translated into the sensible realm, the paper argues that cosmic uniqueness is not strictly required by the logic of image–model relations. Rather, uniqueness is best understood as a choice guided by the Demiurge’s aim to produce the most complete, ordered, and beautiful realization of a pre-cosmic chaotic substrate. This interpretation sheds new light on the practical–theoretical character of the Demiurge’s reasoning and on the status of the eikôs muthos.
Finally, the paper takes seriously Timaeus’ explicit admission (55c–d) of the possible existence of five worlds, arguing that Platonic cosmology leaves room for alternative, non-empirically verifiable cosmic configurations. The resulting picture is one in which Platonic cosmology functions as a sophisticated thought experiment, combining deductive argumentation with counterfactual reasoning to explore the limits of human understanding of the cosmos
