Where's My 'dislike' Facebook Button Already?

This morning I opened up facebook, skimmed my feed, and saw that a friend from high school had posted a video that made an argument that was (in my estimate) intellectually dishonest — and a bit offensive to boot. So I did what any argumentative liberal arts major would do: I challenged the argument. I made sure that the post was polite, but at its core it was deep disagreement. Was I out of line?

I’m not sure, but I think the answer is contigent on whether facebook profiles are public or private spaces — the problem is that there seem to be a lot of ways to define if it is. Facebook is public if you don’t know how to set your privacy settings (or if you don’t care to). It’s also public in that everything said is part of a record over which you don’t have much control (people can easily screenshot, quote, save or remember anything said or done).

At the same time, privacy settings do exist for a reason, so maybe calling a profile “public” is too strong in some regards — these settings exist so that only friends (or at least people you never talked to in highschool) can see what you’re up to and interact with you. At best, facebook is a semi-public (does that equate with semi-private?) space, so how do we decide how we behave in this new space?

In real life (or meatspace, as the kids today call it), the division between public and private space is pretty well defined, something is public if you’re broadcasting it outwardly in a public space. Canadian free speech/hate speech laws are a good example, you can say any number of distateful and hateful things to your friends sitting around a table in a bar, but if you stand up on the table and say those same things a little more loudly, you’re no longer in your own private world, and there very well could be some consequences for “sharing your views.”

How does this situation play out on facebook (or other social networks)? Where’s the line between public and private with regards to what constitutes a public statement? It seems that just to be safe, you have to regard everything as public. But how does this apply to etiquette?

If someone posts something, is it considered fair game for debate or disagreement? Or are the rules the same as at a nice dinner party, where you bite your tongue in favor of social graces? If the space is shared, have you got an obligation to make your dissenting opinion known when someone says something objectionable? What are some possible best practices if you decide to do so?

What do you think?