This chapter focuses on contractarian arguments to bring PSID into our political community. The most obvious argument is by showing that it is advantageous for other members of the community to include them in their ‘cooperative venture.’ This inclusion can be done either directly – by thinking of PSID’s social input differently – or indirectly – by showing that their integration into our community indirectly benefits us, even if they were mostly passive beneficiaries. This first kind of justification, I argue, seems empirically dubious and the latter offers a problematically derivative or contingent status to PSID. I conclude that taking a collectivist, multipartite stance on reciprocal relations to elaborate a kind of rule-contractarianism remains a promising avenue. However, for this argument to be convincing, the contingency objection ought to be met by rendering the inclusion of PSID as less of an opportunistic happenstance and more of a necessity based on their traits and on the nature of the contribution they can provide.