AN ARGUMENT FOR CIVIL UNIONS
P1. Civil unions protect marriage if they allow all ineligible couples many of the benefits of marriage, and are clearly distinct from the institution of marriage
P2. Civil unions allow all ineligible couples many of the benefits of marriage
P3. Civil unions are clearly distinct from the institution of marriage
C. Therefore civil unions protect marriage
This argument follows the typical line of reasoning from policy makers who introduce civil unions.
P2 is not true; other ineligible couples (such as platonic consanguineous couples) also want the benefits of marriage.
P3 is usually untrue because civil unions commonly have the same or similar benefits as marriage, blurring the distinction between civil unions and marriage.