In 1973, sociologist Mark Granovetter published a paper with a counterintuitive finding. He surveyed people who had recently changed jobs through personal contacts and asked how closely they communicated with the person who helped them. The expectation was obvious: close ones help. The reality turned out to be the opposite—most learned about the job opening from acquaintances they saw rarely.
Granovetter's explanation is elegant. Close friends, colleagues, and family form a dense circle where everyone roughly knows each other and moves in the same environment.
Information within such a circle quickly becomes shared: if your best friend knows about a job opening, you likely already know about it yourself. A weak tie, however—a former classmate, a colleague from a past job, someone from an adjacent industry—lives in a different circle. That is precisely why they bring information that does not exist in your circle.
Granovetter called such ties bridges: they connect dense clusters of the network that would otherwise not intersect at all. The value here lies not in the strength of the relationship, but in the novelty of access.
For HR, several practical takeaways follow from this. Referral programs focused only on the immediate circle of employees operate in a narrow field: they bring in candidates similar to those already working there, from the same companies and schools. This is convenient for cultural fit and bad for diversity of experience. A broader phrasing—"whom do you know, even if only superficially"—opens up a noticeably wider pool.
For a career, the conclusion is the same and non-obvious: it is more beneficial to maintain many weak ties than to deepen a few strong ones. Not "making friends with the right people," but simply keeping naturally occurring connections alive: former colleagues, conference attendees, people from related fields. This is not about networking in its unpleasant sense—rather about not cutting off contacts by default.
And separately: if cross-functional connections in a company are weak or non-existent, the organization loses not communication, but information. Bridges between departments are what non-standard knowledge travels across.