Infectious diseases, says the World Health Organization, "are caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi; the diseases can be spread, directly or indirectly, from one person to another." Quite so. Just like Facebook addiction, which also spreads from person to person and has now reached pandemic proportions, with more than a billion sufferers worldwide.

The Facebook pathogen doesn't kill people, of course, for the good reason that dead people don't buy stuff. But it does seem to affect victims' brains. For example, it reduces normally articulate people to gibbering in the online equivalent of grunts. Likewise, it obliges them to coalesce all the varieties of human relationships into a simply binary pair: "friends" vs. everyone else. I have some real friends — as opposed to "friends" — on Facebook and every so often one of them posts a comment on something I've written. I've just looked at one such observation. It's thoughtful, subtle and nicely written. But beneath it is a button simply labeled "Like." If I click on it, my friend will doubtless receive a message from Facebook telling him that I "Like" his comment. Big deal.

What's interesting about this is the way a software system has been designed to strip all of the nuances and complexities that characterize human interaction and compress them into a channel with the bandwidth of Morse code. Actually, the bandwidth is even more attenuated than that. At least with Morse, something can be either a dot or a dash, but Facebook lacks even that binary sophistication. It only has a "Like" button, possibly because a "Dislike" one might facilitate a higher level of discourse than that deemed desirable by the system's architect.