(It seems a bit meta to be writing a blog post about another blog post. I hope you can forgive me.)
Reading this fine example of careful reasoning has me thinking about the issue of marriage. I am pleased with how this argument was made. To summarize, the linked post addresses the argument that allowing homosexual marriage will create a snowball effect that will ultimately end with polygamist marriages becoming legal,* so for the sake of avoiding polygamy, we should not legalize gay marriage. This slippery slope argument (from gay marriage to polygamy) does not hold water, in large part because the arguments for and against each of these things use completely different reasoning. Demonstrating the legal necessity of one does not establish the necessity of the other.
The issue of polygamy isn’t receiving much attention in the media, but how about it? Is it okay for people to marry more than one person? I have to confess that I see little reason this should be universally forbidden.
After all, what’s the difference between an adulterer and a polygamist? And if it’s not illegal for a married man to support a girlfriend or two and father children out of wedlock with them, how can it be illegal for him to bind himself to them according to the laws of his church? Why is a practicing Mormon with two wives a criminal while [a politician, publicly] embarrassed by the discovery of his second family, is simply a punchline?
(Source.)