Democrats and Republicans clearly dislike one another, but scholars disagree about why. Some prior work argues this animus is spurious—driven entirely by inferred policy preferences. This study contends that policy preferences often act as signals of partisan identity when party stances are well-known, and it tests how much interpersonal dislike comes from identity versus policy disagreement itself.

🔎 Data & Design: A nationally representative survey plus four preregistered experiments were used to untangle policy effects from identity effects. The research strategy isolates interpersonal affect driven directly by policy disagreement from affect driven by signals of partisan identity.

📌 Key Findings:

• Partisan identity emerges as the principal mechanism behind affective polarization.
• Policy preferences shape interpersonal affect largely by signaling partisan identity when parties’ stances on an issue are well-known.
• Policy disagreement also has an independent effect on interpersonal affect, confirming that substantive disagreement matters in its own right.

💡 Why It Matters: The results provide evidence that partisanship reflects an emotional attachment to a political party, not merely a running tally of rational considerations. This distinction matters for theory and for designing interventions: addressing affective polarization requires attention to identity-based attachments in addition to substantive policy debates.