The radical reform of welfare provision led by Work and Pensions Secretary Iain Duncan Smith is intended to redress anomalies in the system and "make work pay".
But, as others who have embarked on the mission for social justice have discovered, it is impossible to reduce overall the cost without replacing one form of unfairness with another.
Cuts to housing benefit, which will start to be replaced by a single Universal Credit payment from April next year, and fitness for work assessments for long-term claimants are but the latest examples.
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