Far out: Why political parties go to extremes

The established view is that in a two-party representative democracy, political parties should target the average voter if they want to be re-elected. So why do some political systems become polarized, rather than remain in the center?

Economists at the University of Technology Sydney and Goldsmiths, University of London have modeled the social, economic and personal factors that influence voters, and in turn political parties, to see what factors tip the balance towards political extremes.

They identified four key levers that interact to influence political platforms:

• current economic conditions
• the level of inequality in society
• the social tendency of voters to join the "bandwagon"
• individual factors such as personal or religious beliefs.

"Over the last twenty years, the distribution of voters and parties' agendas on specific issues have moved towards relatively extreme positions," says research co-author Dr. Corrado Di Guilmi from the University of Technology Sydney.

"Increasing inequality, low economic growth, and greater use of social media and 'fake news' have all been discussed as possible causes of this shift towards far-right groups whose ideas were previously on the margins," he says.

Of the four key factors, social contagion from peers and external influences, or the "bandwagon" effect, had the greatest impact in driving strong left or right political majorities, the research showed.

"When neither party has enough support to pursue its agenda, parties will converge, but once one side has social momentum, people gravitate towards the likely winner. This can lead to both parties becoming more extreme," says Dr. Di Guilmi.

"Those in power have an advantage because they can control the message and "sell" what they are doing. We see evidence of this in the US where nearly every president in recent times has had two terms.

"It's also likely that social media feeds this bandwagon effect, because it acts as an echo chamber, spreading and reinforcing majority views," he says.

Macro-economic factors such as employment and economic growth also play a role, as voters hold the ruling party accountable for the economic performance of a country.

"This is why political parties in power will go to great lengths to bolster employment growth and avoid a recession prior to an election, to increase their chances of re-election," says Dr. Di Guilmi.

While a strong economic performance can increase the bandwagon effect, a negative economic performance has to be catastrophic before it negates the bandwagon effect, the research shows.

And while a large divide between rich and poor can push voters and political parties to greater extremes, it also depends on how accepting a population is of inequality.

"Over time the socially acceptable level of income inequality tends to adjust to the actual level of inequality. High levels of income inequality increase polarization, so extreme political views are more likely."

The researchers used a dynamic voting model, where voter preferences evolve over time depending on the four key variables. Voter preferences in turn influence political policies around income distribution, generating a feedback effect on preferences.

While the model is theoretical rather than empirical, a greater understanding of how parties converge or diverge depending on broader social and economic conditions can help society implement policies to reduce political instability and extremism.

The paper 'Convergence and divergence in dynamic voting with inequality' was recently published in the Journal of Economic Behavior and Organization.