MMDad
Lem Putt
There are good societal reasons for incentivising marriage as it exists today.
According to one of our pointless government arms (HHS):(Lack of traditional marriage has) caused a great deal, perhaps all, of the increases in child poverty between the early 1970s and the 1990s (Lerman 1996; Sawhill 1999). In addition, the shift toward single-parent families may have contributed to a higher incidence of other social problems, such as higher rates of school dropouts, of alcohol and drug use, of adolescent pregnancy and childbearing, and of juvenile delinquency (Lang and Zagorsky 2000; McLanahan and Sandefur 1994). Family structure has become so important to the well-being of American children that some observers now argue that marriage is replacing race, class, or neighborhood as the greatest source of division in the U.S. (Rector, Johnson, and Fagan 2001; Rauch 2001).So, why should we incentivise marriage? Because it lowers poverty, increases education and the benefits to society thereof, lowers drug use and other juvenile crimes, lowers adolescent pregnancy......
In short, it has profound effects - all by itself - on society at large.
Again, when same-gendered relationships can show the same benefit to society, they will deserve the same breaks and benefits.
Is marriage the cause or the symptom? Is it that decreased traditional marriage caused all of societies ills? Or did a morally bankrupt society affect marriage?
Polygamy laws preceded this moral decline. The laws were forced onto people who took their vows "for time and all eternity" far more seriously than most "traditional" marriages.
Since you say that the decrease in the number of marriages is the cause, maybe polygamist marriage will fix all of our problems! Imagine that, a more moral society, but they just don't conform to your myopic world view. Hmmmm... Wouldn't that just be awful?