  On either interpretation of the identity and structure of the relevant regress, it is as yet unclear why Parmenides finds the regress problematic. It is reasonable to assume that Parmenides’ reason for finding the likeness regress problematic is the same as his reason for finding the largeness regress problematic in the Third Man argument. The same three options canvassed in section 4.3 are available. Some contend that the regress is epistemic and vicious by its very nature, others that the regress conflicts with Uniqueness, and yet others that the regress leads to the claim that each form in the relevant infinite hierarchy is many, and hence, by Oneness and Purity-F, both one and not one.