Sorry I am being late on the reply, I have unfortunately been preoccupied with a rather ridiculous debate with Lincoln100, which is something I am not particularly proud of.
1) I am very intrigued! So I just read the blurb on Amazon, but I must say that what I read at the very least sounded plausible and worth taking seriously. Here was my main and initial reaction. a) Insofar as their approach is a priori - to define marriage given what it has traditionally been and argue from the basis of that definition - I suspect I would be very sympathetic to their argument (it seems to me uncontroversial that marriage has traditionally been between a man and a woman and a religious practice at that). One concern: do they argue that same-sex couples should not be allowed to "marry," given how they have defined it and think it ought to be defined, or do they make the further (and more difficult) argument that same-sex couples should not enjoy civil-union and the same privileges/rights of those who get to marry (e.g., tax incentives)? I've often thought it might be a worthwhile compromise to allow same-sex couples the same rights/privileges that come with marriage while not actually calling it "marriage," since that idea has the religious tradition and history it does (one complication, though, is that it clearly has become a secularized idea too).
2) As you suspected, I was not using "yet" in that sense. I suspect that homosexuality is not merely genetic, that's one reason. Secondly, and more importantly, my use of "yet" was to maintain logical consistency, as just because no gene has been discovered yet, does not mean that one will not. That is why I put the argument in those terms, as I thought that was the most charitable way to do so and preserve what I thought TT was getting at.
Sorry for taking so long to reply. Like I said, I have a lot going on, plus I wanted to step away so as not to get drawn into a fruitless argument with someone who evidently thinks it is a productive debating technique to belittle, insult, and attempt to bully someone who disagrees with him. The ignore function is a wonderful thing, but I digress . . . . .
To answer your question: the authors contend that one cannot have a clear thinking and reasoned debate about gay marriage unless there is an understanding on both sides of what marriage really is. They therefore seek to define what marriage is historically (their contention is that it is a monogamous, life long, comprehensive union between one man and one woman), why that is important to a healthy society (which is why governments have always done things to promote traditional marriage - ie. tax breaks, etc.), and how "changing" that definition results in all kinds of problems on all kinds of different levels. I would note that marriage has already largely been redefined from its historical understanding with the advent of no fault divorce, etc., etc., and that changed understanding has resulted in societal ills such as much higher divorce rates, a higher number of illegitimate births and children living in one parent homes, and all the negative impacts those things have on graduation rates, levels of drug and alcohol abuse, incarceration rates, mental health and on and on.
They do contend that opposite gender couples are a vital aspect of what marriage really is and therefore do not believe same sex couples should be allowed to marry because that's not what marriage is. However, they do believe that there are things that can be done in order to assure that property rights, hospital visitation rights, etc. can be afforded to same sex couples.
In regards to my previous posts on the whole "gay gene" contention: from the author's perspective, it is irrelevant to whether or not a marriage between two people of the same sex is truly a marriage or not. It's really more or less irrelevant to me, too. Just don't like it when people say that there has been a study that definitively proves the "gay gene" when there hasn't. But, again, I digress.. . . . .
I would really encourage you to read their work. They obviously do a much better job laying out their arguments than I could ever hope to. It is availble on Kindle for about $9 and isn't a very long read. If you do read it, I'd be interested to hear your thoughts.
Thanks again for the cordial exhange. Wish I had more time for it and wish I ran into more people willing to conduct themselves with the charity that is necessary for a fruitful exchange of ideas.
Oh, and I love Hemingway.
God bless.