 The group mind hypothesis thus seems to explain or account for the rationality exhibited by the group, both in what it does and what it represents. This explanatory role, if indispensable, would give us a reason for admitting into our ontology groups with genuine minds of their own. The point might be put in traditional Quinean terms: if a regimentation in first order logic of our best empirical theory quantifies over such groups, then such groups exist. But this sort of explanatory commitment needn’t be quite as explicitly quantificational as Quine would have it, and Pettit himself never mentions Quine. The ontological commitment might be more implied in the content of our theory than a matter of logical form.