The article traces recent political polarization to earlier institutional
reforms opening up the political system to increased electoral competition.
The increased ináuence of the rural majority led new political entrepreneurs
to introduce welfare policies. The new polices were opposed
by urban tax payers, setting o§ a process of policy driven polarization
that drew on underlying cleavages in Thai society. Empirical tests based
on voting patterns in the most recent general election using a seemingly
unrelated regression model provide support for the hypothesis of policy
driven political polarization. The analysis highlights the vulnerability
to increased polarization after introduction of institutional reforms that
alter the balance of power between di§erent parts of the electorate. It
is noted that neither reversals of institutional changes nor policy reversals
are e§ective for stopping negative cycles of increased polarization,
whereas inclusive and policy based public debate can lower polarization