AN ARGUMENT FOR PLATONIC CONSANGUINEOUS MARRIAGE
P1. Romantic same-sex couples and non-romantic same-sex couples (such as sisters) should have equal rights
P2. Romantic same-sex couples have the right to marry
C. Therefore non-romantic same-sex couples (such as sisters) should have the right to marry
CONSERVATIVE COMMENTARY
Judge Vaughn Walker, who overturned California’s Proposition 8, said in the ruling:
Marriage is the state recognition and approval of a couple’s choice to live with each other, to remain committed to one another and to form a household based on their own feelings about one another and to join in an economic partnership and support one another and any dependents.
http://www.casavaria.com/cafesentido/wp-content/uploads/2010/08/35374462-Prop-8-Ruling-FINAL.pdf
On this understanding of marriage it is difficult to argue that non-romantic same-sex couples (such as siblings) should not have the same rights as romantic same-sex couples.
In the words of Sherif Girgis, Robert P. George, & Ryan T. Anderson:
Assuming a general policy of recognizing committed dyads, should the benefits that Oscar and Alfred receive depend on whether their relationship is or can be presumed to be sexual?
Girgis, Sherif and George, Robert and Anderson, Ryan T., What is Marriage? (November 23, 2012). Harvard Journal of Law and Public Policy, Vol. 34, No. 1, pp. 245-287, Winter 2010, Available at SSRN: https://ssrn.com/abstract=1722155