In Part I, I discussed how the conviviality externality can cause people to issue too many social invitations, which on average makes people worse off. In Part II I argued that the friendship paradox from the theory of social networks exacerbates this pressure to socialize.
As a quick reminder, the friendship paradox is the finding that on average your friends have more friends than you have. I argued that this meant that they are highly gregarious people who issue lots of invitations--more than most of us would like to see. I now consider an objection, and a response: signaling.
A possible objection to all this is that getting more invitation doesn't really hurt anyone; they're always free to say no. However, many people find it awkward to decline invitations, and for a good reason: signaling. Suppose that people tend to accept invitations from people they like, and reject invitations from people they dislike. Then the act of turning down an invitation sends a bad signal to the host. Sure, it's a noisy signal: maybe she really does need to wash her hair. But the signal has some content, so saying no does have a cost.
Signaling incentives on the inviter's side makes the problem of over-conviviality even worse. Suppose that people tend to invite people they like to parties more than people they don't like. Then party planners will be pressured to invite more people than they would really like to, in order to signal to more people that that they like them, and to avoid snubbing those they are not well-acquainted with.
How upset do people get when they are left off your invitation list? Consider the ancient Greek goddess Eris, who was so angry that she was not invited to the wedding of Peleus and Thetis that she showed up with an apple of discord, together with a gift card coyly addressed: "To the fairest." This provoked a bitter argument between Athena, and Aphrodite and Hera, that eventually resulted in the Trojan War.
It's people like Eris who create a temptation, when planning a party, to bloat the invite list. Of course, that means that parties get too large, and include people who don't match the group (or like Eris, are just obnoxious). So to sum up, signaling incentives cause more invitations and more acceptance of these invitations, to parties that are less fun.