When sharing or retweeting, we like to think of ourselves as engaging in what philosophers would call an act of testimony — trying to convey or endorse knowledge. Not always, of course; happily, irony still exists. Yet insincere sharing or retweeting is not the norm — as evidenced by the fact that most people feel obligated to signal that retweets aren’t endorsements. That wouldn’t make sense if the default wasn’t that shares and retweets are endorsements.

But what if we are just confused about the way communication actually functions online? Clues can be found in both what we do and don’t do when sharing content online.

Let’s start with what we don’t do. Current research estimates that at least 60 percent of news stories shared online have not even been read by the person sharing them. As an author of one study summed up the matter, “People are more willing to share an article than read it.” On the other hand, what we do is share content that gets people riled up. Research has found that the best predictor of sharing is strong emotions — both emotions like affection (think posts about cute kittens) and emotions like moral outrage. Studies suggest that morally laden emotions are particularly effective: every moral sentiment in a tweet increases by 20 percent its chances of being shared. And social media may just pump up our feelings. Acts that don’t elicit as much outrage offline, for example, elicit more online, perhaps because the social benefits of outrage still exist without the normal risks.

This should tell us that conveying knowledge isn’t the primary reason news stories are shared. As the influential contemporary philosopher Ruth Millikan puts it, the stabilizing function of a communicative act is whatever explains why that act continues to persist. The stabilizing function of yelling “Air ball!” at a basketball player trying to make a free throw is to distract him. It may do other things too — amuse people, or even describe what, in fact, turns out to be an air ball. But the reason people continue to yell “Air ball!” it is that it is distracting. Someone new to the game could conceivably get this backward. They might think that people are warning the player or predicting how the shot is going to fall. Such interpretations would be a misunderstanding the act’s stabilizing function.

Something like this is happening on a massive scale on social media. We are like the person just described, new to the game of basketball. We think we are sharing news stories in order to do one thing, like transfer knowledge, but much of the time aren’t really trying to do that at all — whatever we may consciously think. If we were, we would presumably have read the piece that we’re sharing. But most of us don’t. So, what are we doing?