D: A democracy in which a majority of people believe they make themselves better off by voting themselves money through the public trough.

Pork barreling is rife in social democracies, as everyone tries to live at everyone else's expense.

Governments realize that the electoral cost of increasing taxes is lower than than the benefit from spending the money to pork barrel, and taxes slowly spiral upwards.

A favorite analogy is with frogs in hot water. If you put a frog into boiling water it will hop out immediately, but if you put it in cool water and slowly heat it, you can boil it alive.

A century ago, democratic governments would not have survived the imposition of a tax regime in which 40% of GDP was taken in government taxes - they would have been thrown out of office at the following election. At the start of the 21st century, 40% is a low figure for many democracies.

Is there a limit to how much governments will tax their citizens? Will taxes spiral forever to the point of economic collapse? No. Taxes reach the maximum point on the Laffer curve and governments, wanting to maximize their pork barreling funds will not go beyond that.

See