The More Parties, the Greater Policy Stability
The outcome of the United Kingdom election in 2010 overturned long sustained beliefs about the virtues of Westminster-style governance. At least for a while, the country has moved to the kind of multiparty coalition politics that is more common in other parliamentary democracies. The new Prime Minister, David Cameron, said that the new Conservative-Liberal coalition government ‘marks a clean break from the past and a new start for the country’. He may have meant a break with not only the previous period of Labour party governments, but with several decades of single-party governments and significant instability of major public policies.
The attached article discusses, models and quantifies the relationship between the number of parties in government and the degree of policy change or instability. Single-party governments, such as those formed in the United Kingdom for several decades, tend to produce very high levels of policy changes and reversals, whereas multiparty coalition governments, such as the ones in Switzerland or Israel, tend to produce a high degree of stability and little policy change. This relationship is studied for 295 elections and the subsequent governments in twenty-four countries since the Second World War. According to the study, there is a strong negative correlation between the number of parties in government (NPG) and the degree of policy change (Ch), according to the formula:
30% / NPG = Ch
The fewer parties in government the more changes, and vice versa.
For the article, as published in the journal European Political Science: