Conservative Argument


P1. Marriage is a legally-binding long-term relationship

P2. Polyamorous marriage channels romantic groups into marriages 

C. Therefore polyamorous marriage channels romantic groups into legally-binding long-term relationships


This argument is also used for:

Legally-binding long-term relationships are generally good for society but  Sherif Girgis, Robert P. George, & Ryan T. Anderson question what this would mean for marriage. The quote below concerns same-sex marriage but is equally applicable to polyamorous marriage:

[The conservative argument] assumes that the state can effectively encourage adherence to norms in relationships where those norms have no deep rational basis—no reason for partners to stay together and exclusive, even if desire wanders or wanes or attachment erodes. Laws that restrict people’s freedom for no deep purpose are not likely to last, much less to influence behavior. 

But redefining civil marriage would not just be idle in this respect; it would be counterproductive. Over time, people tend to abide less by any given norms, the less those norms make sense. To say it again, if marriage is understood as an essentially emotional union, then marital norms, especially permanence and exclusivity, will make less sense. But whatever the morality of flouting these norms in other relationships, they do, in opposite-sex relationships, serve the interests that hook the state into recognizing and supporting marriages in the first place. So those who champion the conservative objection are right to think that redefining civil marriage would produce a convergence—but it would be a convergence in exactly the wrong direction.

Girgis, S., George, R. and Anderson, R., 2012. What is Marriage?: Man and Woman: A Defense. 1st ed. New York: Encounter Books.