Any reductive moral framework that abstracts every possible political position into interchangeable spherical cows in a vacuum does a disservice to its users.
The two scenarios are precisely symmetrical. The only difference is that the cause on one side is one that you agree with, and on the other side is one that you disagree with.
You cannot decide moral questions by couching them in terms of “rights” and assuming that whichever side “advances rights” must be the correct side. Why? Because you can do that arbitrarily either way and for anything. e.g. “admitting gay marriage denies people the right to live in a society where traditional marriage is protected”.
Now what do you do? Both sides can say their cause is “advancing rights”.
Yep! That's pretty much what agreeing or disagreeing with something means.
But the reasoning you seem to be proposing is "here is something you agree with and something you disagree with, therefore those two things are interchangeable and you should not favor one over the other."
> Now what do you do? Both sides can say their cause is “advancing rights”.
I exercise human discretion and decide which of those rights is better, more valuable, more important.
In this case, that's not a tough call. Marriage provides a bunch of very concrete mechanical effects, from inheritance to medical decision making to finances to immigration. Whereas some people feeling happy about the fact that some other people can't access those rights is, at best, abstract and intangible.
And you'll also note that some of my previous references were to the uniformity of rights. Generally speaking, making rights more uniformly accessible to all people is better than having rights be selectively, arbitrarily limited to some people.
>Yep! That's pretty much what agreeing or disagreeing with something means.
Not to me. The difference between us is that I am perfectly happy to work with people who do not share my political viewpoints.