Working Paper: CEPR ID: DP13771
Authors: Yann Algan; Nicol Dalvit; Quocanh Do; Alexis Le Chapelain; Yves Zenou
Abstract: We study how social interaction and friendship shape students' political opinions in a natural experiment at Sciences Po, the cradle of top French politicians. We exploit arbitrary assignments of students into short-term integration groups before their scholar cursus, and use the pairwise indicator of same-group membership as instrumental variable for friendship. After six months, friendship causes a reduction of differences in opinions by one third of the standard deviation of opinion gap. The evidence is consistent with a homophily-enforced mechanism, by which friendship causes initially politically-similar students to join political associations together, which reinforces their political similarity, without exercising an effect on initially politically-dissimilar pairs. Friendship affects opinion gaps by reducing divergence, therefore polarization and extremism, without forcing individuals' views to converge. Network characteristics also matter to the friendship effect.
Keywords: Political opinion; Polarization; Friendship effect; Social networks; Homophily; Extremism; Learning; Natural experiment
JEL Codes: C93; D72; Z13
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| friendship (Y92) | reduction in differences in political opinions (D72) |
| integration group assignment (F02) | friendship (Y92) |
| friendship (Y92) | decrease in political polarization and extremism (D72) |
| politically similar students (D72) | more likely to reinforce their views through shared activities and friendships (C92) |
| friendship (Y92) | reduction in divergence of opinions (D79) |
| friendship (Y92) | reduction in overall opinion gaps (I24) |