 There are many ways in which one can attempt to block the argument. However, the key feature related to our discussion is the following. Several versions of the indispensability argument rely on a holistic conception of scientific theories according to which the ontological commitments of the theory is determined by looking at all the existential claims implied by the theory. However, no attention is paid to how the different parts of the theory might be responsible for different posits and to the different roles that the latter might play. Baker 2005 offers a version of the indispensability argument that does not depend on holism. Baker starts from a debate between Colyvan (2001, 2002) and Melia (2000, 2002) that saw both authors agreeing that the prospects for a successful platonist use of the indispensability argument rests on examples from scientific practice in which the postulation of mathematical objects results in an increase of those theoretical virtues which are provided by the postulation of theoretical entities. Both authors agree that among such theoretical virtues is explanatory power. Baker believes that such explanations exist but also argues that the cases presented in Colyvan 2001 fail to be genuine cases of mathematical explanations of physical phenomena. Most of his article is devoted to the specific case study from evolutionary biology concerning the life-cycle of the so-called ‘periodical’ cicada, which was described in section 1. Recall that the question of interest was why the life cycle periods of such cicadas are prime numbers and that the answer appealed to evolutionary facts and mathematical properties of prime numbers. After the reconstruction of the explanation, Baker concludes that: