Why I still send holiday cards – and perhaps you should, too

WITH every Christmas card I write, I’m dreaming of a white Christmas, but I’m also pondering The Strength of Weak Ties, a seminal 1973 paper by the sociologist Mark Granovetter, then of Johns Hopkins University, now of Stanford.

Granovetter wrote that weak ties between people have a “cohesive power” that strong ties lack. You have strong ties to a handful of people but you have weak ties to many. It’s those weak ties that expose you to new ideas and facts. If you’re looking for a job, for example, you’re more likely to find one through a weak tie.

“Those to whom we are weakly tied are more likely to move in circles different from our own and will thus have access to information different from that which we receive,” Granovetter wrote. Also, he added, two groups that are isolated from each other can become connected by one person through a tie that is “weak” yet vital.