## 4.2 Reading two seminal papers

### 4.2.1The Strength of Weak Ties by Granovetter (1973)

Granovetter, M. S. (1973). The strength of weak ties. American journal of sociology, 78(6), 1360-1380.

This is a highly influential paper: more than 58K as of Nov. 2020.

• Overlap in friendship circles: Suppose there are two individuals, A & B, and a group of people, S = C, D, E. The stronger the tie between A and B, the more people in Group S will be tied to both A and B.

• If there is a strong tie between $$A$$ and $$B$$, and between $$A$$ and $$C$$. It’s very likely that $$B$$ and $$C$$ also are friends, because

1. A common contact will bring $$B$$ and $$C$$ into interaction;
2. The stronger the tie, the more similar are individuals to each other. $$A$$ is similar to $$B$$, and $$A$$ is similar to $$C$$, and thus $$B$$ is similar to $$C$$, making it more likely for them to be friends; and
3. If $$B$$ and $$C$$ are aware of each other but are not friends, they might have a “psychological strain” since their feelings are not consistent with $$A$$.

Therefore, this tried in Figure 4.4 is very unlikely to occur:

• A bridge is a link connecting two otherwise disconnected groups. “No strong tie is a bridge.” All bridges are weak ties.

• A local bridge of $$n$$: if this bridge does not exist, what is the shortest path between these two points?

• No strong tie is a local bridge.

• Whatever is is to be diffused can reach a larger number of people if passed through weak rather than strong ties2.

• People are more likely to find jobs through weak ties rather than strong.

Something I do not understand yet in this paper: “Thus, network fragmentation, by reducing drastically the number of paths from any leader to his potential followers, would inhibit trust in such leaders.”