Political Polarisation I

I have been struggling to understand what happened to British politics between 2016 and 2019. A fissure opened up following the referendum which grew in time to a chasm. The country did not just divide, as time went on each tribe moved more towards the extremes. As part of my investigation I have come up with this simple model. It looks at polarisation without reaching for any psychological or behavioural explanations, which is why I refer to it as "rational".

A Rational Model of Political Polarisation

Policymakers make choices. The essence of decision is to choose between alternatives, at least in a rational model. To simplify, suppose a policymaker has to decide between option A and option B. Both advance the policy towards its goal. Option A has certain advantages, but also some downsides. Option B has some disadvantages and certain benefits. The rational decisionmaker then chooses, trading off benefits and costs of the different options

Policymaker
Option A	Option B
Advantages of option A	Disadvantages of option B
Disadvantages of option A	Advantages of option B

 

The policymaker operates in a political environment where lobbyists and campaigners will advocate for their preferred solution. From this perspective the information which matters to their case will be the advantages of their favoured option and the disadvantages of the alternative. The Lobby for A will emphasise the benefits of A and the problems of B. The campaign for B will do the reverse.

This can be summarised in the table below. While the rational policymaker must assess the trade-offs of the decision, campaigners have a simpler time highlighting the factors which suit their viewpoint.

	Policymaker
	Option A	Option B
Campaigner for option A	Advantages of option A	Disadvantages of option B
Campaigner for option B	Disadvantages of option A	Advantages of option B

 

The model demonstrates that even a rational decision process, under political conditions, has within it the seeds of polarisation. To give concrete examples, replace option A with Scottish independence and option B with retaining the union. Campaigners for Yes (independence) set out a vision of how a self-governing Scotland would operate and of the problems of union, such as the times when the UK is governed by a party rejected by Scots voters. No campaigners focused mostly on the costs of independence, particularly the economic impact. The benefits were fiscal and social, such as ties of family across national identity.

In the aftermath of the referendum, when voters have picked a side, they are caught up in the campaigner perspective rather than the policymaker viewpoint. They can explain their choice by reference to the advantages of A plus disadvantages of B (or vice versa). This explains the different distribution of viewpoints across the range of possible positions.