I am sick to the teeth of reposting this every few weeks, so I am going to put it here now that I have a blog and just link to it.
In early 2011, Robert P. George, a prominent social conservative from Princeton, plus some colleagues of his, published “What Is Marriage?”, which is generally considered the definitive case against same-sex marriage from a non-religious perspective. (Note that “definitive” is not the same as “conclusive.” Many conservatives I know would quibble with George on a number of points both minor and major.)
Here is “What Is Marriage“: https://www.harvard-jlpp.com/wp-content/uploads/2011/08/GeorgeFinal.pdf
That paper kicked off an EPIC marriage debate among online intellectuals. It is ALL worth reading — both sides make serious arguments. If you want to actually have a conversation about gay marriage, rather than just resorting to your Bible or to calling all your opponents hateful bigots, this is a great place to start. Although I have sorted them, I have tried to keep the conversation in chronological order, since the various critiques build on each other at times:
Kenji Yoshino’s critique (I): https://www.slate.com/id/2277781/
Robert George’s reply: https://www.thepublicdiscourse.com/2010/12/2217
Andrew Koppelman’s critique (I): https://balkin.blogspot.com/2010/12/what-marriage-isnt.html
Robert George’s reply: https://www.thepublicdiscourse.com/2010/12/2263
Barry Deutch’s critique: https://familyscholars.org/2010/12/21/what-is-bodily-union-a-response-to-what-is-marriage/
Robert George’s reply: https://www.thepublicdiscourse.com/2010/12/2277
Kenji Yoshino’s critique (II): https://www.slate.com/id/2278794/
Robert George’s reply: https://www.thepublicdiscourse.com/2011/01/2295
Andrew Koppelman’s critique [of Yoshino]: https://balkin.blogspot.com/2010/12/that-elusive-timeless-essence-of.html
Robert George’s additional comments: https://www.thepublicdiscourse.com/2011/01/2350
That’s the basic discussion that took place at the time. I also recently found an earlier, tangentially-connected exchange from about a year earlier:
Andrew Koppelman’s paper: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1544478
Robert George’s critique: https://mirrorofjustice.blogs.com/mirrorofjustice/2010/02/more-on-koppelmans-paper.htm
Andrew Koppelman’s defense: https://balkin.blogspot.com/2010/02/koppelman-vs-george-on-same-sex.html
George later posted two further articles on the subject of marriage at Public Discourse:
“Marriage and Procreation: Avoiding Bad Arguments“: https://www.thepublicdiscourse.com/2011/03/2637
“Marriage and Procreation: The Intrinsic Connection“: https://www.thepublicdiscourse.com/2011/03/2638
It’ll take a smart person the best part of a day to do all this reading, but it’s crucial to do this or something like it if you’re on *either* side of the debate and want to have a serious conversation.
I should note that I don’t think George is 100% right. His defense of marriage for knowingly infertile couples doesn’t really add up from a civil standpoint, in my opinion. But, like I said at the outset, this is a starting point for intelligent discourse, not a conclusion.
And, yeah, this is kinda the Robert P. George show. If you want an introduction to the issue from a secular pro-natural marriage perspective, that’s where you go. You want more complexity, or to deal with specific objections within the two broad camps, you dig deeper. But this is an overview.
Enjoy!