Should We Legalize Polygamy?

Although I fancy myself a man of passions -- even strong passions -- loyal, experienced readers of this blog are sure to know that few issues -- no matter how controversial -- are likely to give me the vapours (except, of course, egregious mistakes in the noble field of epistemology).  Therefore, it might come as something of a shock when I confess that the issue of legalizing polygamy has all but reduced me to my smelling salts.

The problem, you see, is I can't make up my mind whether I am for or against the legalization.

On the one hand, I can think of at least two powerful arguments for the legalization:

1. As a general principle, I favor allowing informed, consenting adults to choose whatever marriage arrangements they deem best for themselves.  By the same token, I believe that the marriage arrangements of informed, consenting adults should not be restricted -- unless a weight of reason and evidence demonstrates those arrangements to be injurious to others.
2. It has been my experience that a person can have more than one great love in his or her life.  But to restrict marriage to two people would seem to force some people to cruelly reject or deny at least one of their loves.  Consequently, I believe restricting marriage to only two people should never be done for light and transient reasons -- but only for the soundest of reasons.

Either one of those reasons alone would be enough to satisfy me that we should legalize polygamy -- except for the fact there seem to be several reasons not to legalize it.  The best summary I've found of the reasons against legalization comes from a Canadian court case.

In 2010, the Supreme Court of British Columbia was asked to reconsider a ban on plural marriage. The core issue was whether polygamy was bad for society.  That is, whether anyone besides the partners to a polygamous marriage were harmed by it.

As part of its deliberations, the Supreme Court called upon the expertise of Joseph Henrich, an inter-disciplinary professor whose scientific credentials are so extensive they require 17 pages to list and are of such quality as would be lightly dismissed only by a madman or a Republican candidate for the presidency.  That's not to say Henrich is above being wrong -- for who among us is -- but only to suggest his findings might be worth some consideration by reasonable folk.

Before being called upon by the Court, Henrich had never published on polygamy nor formed any reasoned and evidenced opinion of it.  However, after reviewing a large body of evidence from several fields -- including psychology, anthropology, sociology, and economics -- he reached several provisional conclusions. His conclusions, however, dealt with only one aspect of polygamy -- polygyny, or the marriage of a man to multiple wives (.pdf pp. 25):

• A non-trivial increase in the incidence of polygyny, which is quite possible if polygyny were legalized given what we know about both male and female mating preferences, would result in increased crime and antisocial behavior by the pool of unmarried males it would create.
• Greater degrees of polygyny drive down the age of first marriage for (all) females on average, and increase the age gap between husbands and wives.  This generally leads to females marrying before age 18, or being "promised" in marriage before age 18.
• Greater degrees of polygyny are associated with increased inequality between the sexes, and the relationship may be causal as men seek more control over women when women become scarce.
• Polygynous men invest less in their offspring both because they have more offspring and because they continue to invest in seeking additional wives.  This implies that, on average, children in a more polygynous society will receive less parental investment.
• Greater degrees of polygynous marriage may reduce national wealth (GDP) per capita both because of the manner in which male efforts are shifted to obtaining more wives and because of the increase in female fertility.

Henrich then offers the Court what seems to me substantial evidence for his provisional conclusions.  But, perhaps even more striking than his conclusions, he goes further to offer the Court "a speculation".

That is, he suggests that monogamy -- which is historically much rarer among our societies than polygyny -- might be linked to democracy and gender equality (.pdf pp. 64): "Historically, we know that universal monogamous marriage preceded the emergence of democratic institutions in Europe, and the rise of notions of equality between the sexes."  The idea there might be a relationship between monogamy and social and political equality is intriguing, although I gather much more work would need to be done for the claim to be reasonably evidenced.

Now, I myself am a polyamorous individual.  I have experienced at least three great loves in my life -- women I have been inordinately passionate about -- women who, at times, I have even loved more deeply and truly than ever I loved a well-formulated operational definition.  Consequently, I'm conflicted by Henrich's findings.

Fortunately, I never had to choose between one of those loves and another since several years separated each from the other.  But I can imagine how cruel it would have been had I been forced to choose. Yet -- if Henrich is right -- the consequences of legalizing polygyny seem to me dire enough to warrant the ban of it.

What do you think?  Should we legalize polygyny?  Why or why not? And, just out of curiosity, have you ever found yourself profoundly in love with two people at once?