A Bad Argument Against Same-Sex Marriage

I would have scarcely believed it possible, but a few short hours after teaching the naturalistic fallacy in my Philosophy of Biology class, I was exposed to an argument–from a professional philosopher–that, roughly, same-sex marriage is problematic because a) marriage is all about procreation and the raising of children and because b) evolution tell us that reproductive success is important, therefore: Gay marriage should be frowned upon. This resistance then, has nothing to do with religion, God, or the divine sanctification. Rather, it is the scientific thing to do: resist gay marriage because it is against evolutionary demands made on us as a species. This means that active disapproval of homosexuality–societal and legal discrimination for instance–is an expression of a biological instinct and should not be condemned as a moral failing.

The outlines of this argument should be familiar to most folks. It has been made time and again and despite having been spectacularly debunked, it rises again and again, like a zombie, or your favorite refusing-to-die cinematic ghoul.

What this argument attempts–and fails–to do is derive a proposition with normative import from a set of propositions that are purely descriptive. This–as David Hume pointed out a long time ago in his A Treatise of Human Natureis an instance of the naturalistic fallacy, an attempt to bridge the is-ought gap:

In every system of morality, which I have hitherto met with, I have always remarked, that the author proceeds for some time in the ordinary ways of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when all of a sudden I am surprised to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is however, of the last consequence. For as this ought, or ought not, expresses some new relation or affirmation, ’tis necessary that it should be observed and explained; and at the same time that a reason should be given; for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it.

This fallacy manifests itself in the current situation as follows. There are biological facts about us: We reproduce, we pass on our genes, various reproductive strategies are adopted, some work better than the others (in securing more offspring to whom we can pass on our genes). This much can be ascertained by observation and measurement. But what should  we do on noting these observations? The proponent of the argument noted above, wants to derive the following: Those reproductive strategies that work ‘better’ are ‘good’, and therefore should be encouraged, should be praised. The rest should be condemned. (Marriage, it will be noted, has been admitted as a successful reproductive strategy; this is a matter of empirical assessment and could well turn out to be false.)

But whence ‘better’, whence ‘good’? Why is ‘reproductive success’ a moral good to be sought? What is the source of that valuation and why is it allowed to override other values in the derivation above? Might we be allowed to admit other values in arriving at an alternative conclusion? Like, for instance, a more tolerant society is a ‘better’ society than one that isn’t? But then, we would be opening up a debate–conducted within some broad ethical and moral frameworks–on valuation, which is precisely what our protagonist didn’t want. He merely wanted the straightforward elevation of reproductive success to the preeminent moral value without further debate.

The tireless proponents of the so-called evolutionary arguments against same-sex marriage forget that efforts to read normative judgments off the historical workings out of the evolutionary process have as much difficulty in bridging the is-ought gap as any other species of argument. Calling upon biology here is not the scientifically sophisticated thing to do; it is merely to reveal one’s ignorance of the limitations of evolutionary explanation.

13 thoughts on “A Bad Argument Against Same-Sex Marriage

  1. The truth is of course that people like this just don’t like gays and don’t want them to have the same rights and privileges that straight people have. They should just come out about it.

    1. David,

      Yup; it’d be way more honest. Instead, we get so much sophistry dished out – from people who should know much, much better.

      In any case, I really think this is one area of human rights where advance seems guaranteed (and indeed, has been rapid.)

      1. Guaranteed, eh? Maybe it looks that way in Brooklyn. A number of years ago, here, in Missouri, a state constitutional amendment banning gay marriage passed with 70% of the vote. North Carolina just passed one of the most draconian measures yet. For a comprehensive list of the states that have passed such measures:


        You need to get out of the New York alternative universe, as it is in no way representative of American opinion. Gay hating is alive and well and shows little sign of abating. The only people who’ve been convinced are the ones who already were. And given that Mitt Romney has a very good chance of getting elected–and given that the evangelicals who will have put him there will be emboldened even further as a result–and the quest for gay equality may still be decades off. A long time—even a lifetime—if you are a gay person, now, trying to live and love and be treated with respect by your nation.

        I am on your side on this, but I find this triumphalism premature and a bit distasteful. No victory dances going on here in the American heartland…or the South.

        –Dan K,

      2. Dan,

        I didn’t mean to sound triumphalist. My only claim is that some important substantive advances have been made which appear to be part of a trend. The measures you mention are reactionary responses to this; they are entirely expected given this trend. But even the Republican Party, troglodytic as it is, cannot be overly homophobic (to an extent); that’s saying something. The ever-increasing visibility of gay life, not just in NYC, but in many different parts of the world, and even the US, gives me cause for hope.

  2. Samir:

    Forget the term “triumphalist.” My point is that what you are describing as “assured” is hardly so, anywhere outside of New York and a few other liberal enclaves. And Republicans in state houses in places like Missouri are overtly, rabidly homophobic. Indeed, it’s a vote-getter.

    I would say that nationwide-gay rights is about as “assured” today, as nationwide civil rights for blacks was after the Civil War. Official emancipation was followed by a century of Jim Crow. The same is likely to be true here. For those gay people who can afford to live in New York or California, things are great. But for those who live in the lower Midwest and South…things are no better than they were thirty years ago. They may even be worse, given that thirty years ago, there was not so much exposure of the issue and thus, so long as you kept your head down, you might actually have been left alone.

    –Dan K.

  3. Follow up: In Colorado, a bill that would have legalized Civil Unions just went down. The deciding vote? A Republican with a *gay son*.


  4. I like your thoughts, but I always prefer to take down the “reproductive” argument against same-sex marriage with a simple question. If marriage is only for raising children, why do we allow men and women who can’t have children or don’t want to have children to marry?

    This doesn’t penetrate the true believers, of course. But you do occasionally see a psychological “flinch” cross their faces. It’s not much progress. But it’s a start.

    1. Peter,

      That’s a good one as well. Seems like the state should conduct fertility tests then before allowing people to marry! This is the problem with coming up with ludicrous justifications for prejudice.

  5. http://www.scottlively.net/2013/03/04/the-bi-sexual-td-in-the-gay-wedding-punchbowl/
    “Marriages based on various forms of sodomy are unclean counterfeits that destroy true marriage by invalidating its central purpose, which is to enclose the procreative natural family in a socially unique protective cocoon. Once marriage stops being unique to the “one flesh” male/female procreative union, the concept of marriage loses all meaning.” And how does that stop reproduction? You confuse an ought for an is… This is an argument from uniqueness.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: