Then there is Twitter’s facility for encouraging tribalism or what is often called the “siloing” of information. People can and do curate their feeds to ensure they hear and interact only with ideas and arguments that reinforce what they already believe, and dismiss anything that might prompt them to question it. Though for many the term “dismiss” is too passive. That’s because they also seek out the most extreme versions of ideas and ideologies they detest in order to reinforce the prejudices that prevail within their own meticulously curated digital world. They band together with allies and then go in search of monsters to destroy.

But what if the causality runs just as much in the other direction — not from tribalism to ideological conflict, but the reverse? What if certain people, at least, are motivated at bottom by a craving for conflict, and they form or join together with groups of the like-minded as a byproduct of that agonistic instinct? In that case, Twitter would have to be understood as an engine of antagonism, augmenting and amplifying a deeply ingrained human predilection for discord and dispute, quite apart from the substance of what anyone is fighting about at any given time.

The obvious example is the figure of Donald Trump, whose every combative, insulting tweet becomes an occasion for his critics on the left, center-left, and center-right to point and shout and hurl invective — and for his abundant defenders on the right to scream in response, “Aw, look at the poor libtards driven mad by the Bad Orange Man and their Trump Derangement Syndrome!”