The Facebook mood experiment was highly unethical. But we all need to remind ourselves that everything we do on Facebook, we do voluntarily. That includes everything we post and everything we read. I look at Facebook as a passive medium that has zero value except to the degree that it facilitates conversation between me and my circle of friends. It fails as a medium if it doesn’t show me what the people I’m interested in are saying. But I doubt it’s deliberately hiding things from me.
It might have found that it could influence people’s moods, and that’s scary when you think of the influence media have had — most vividly in the run-up to the Iraq invasion, where media were complicit in the selling of the lies that justified that conflict. But that kind of influence isn’t unique to social media. Facebook certainly didn’t invent it.
Facebook deserves the kind of shaming we subject people to when they get drunk and do stupid, antisocial things. But I don’t think it’s committed any crimes.