The Government's plan to use the benefits system to punish low-paid workers for striking is more than just an astonishing attack on the right of the lowest-paid workers in Britain to strike. It is also a false economy.

The aim is ostensibly to reduce the benefit bill by not "subsidising" strikers who earn under £13,000, or whose strikes take their income below that level. Yet the only reason those strikers cost the benefit system anything is because we as a society understand that, to have an acceptable quality of life, you need to earn more than many jobs pay. As a result, we have a welfare state designed to top up the incomes of the poorest in society.

There are two ways to reduce that benefit bill. The first is to lower our standards when it comes to how we can accept the poorest living. In many other actions, the government have pursued this course – that's why we saw, for example, a cap on total benefits, which has the the effect of lowing the standard of living for anyone on benefits in central London with "too many" children. And its sort of what the government are doing in this case, telling strikers that they are prepared to countenance them having a worse standard of living than non-strikers.

But the other way to reduce the benefit bill is to make sure that people earn more. The higher someone's wage, the fewer benefits they can claim. And one of the best ways to do that is by encouraging strong unionisation.

The TUC reports (pdf) that unionised workers earn, on average, 12.5 per cent more than non-unionised ones. Clearly some causality goes both ways – many of the poorest workers are temps, for example, who find it extremely difficult to unionise – but it is inarguable that the union movement has resulted, in its hundreds of years of history, in massive material improvements to the living standards of the worst paid. And all of their success comes down, in the end, to the power of the strike.

Fewer strikers means weaker unions, and weaker unions means, eventually, worse paid workers. Which all plays back into a higher benefits bill for this and future Governments.

So if Iain Duncan Smith wants to attack the very concept of unions, he's going the right way about it, but if he wants to save his Government money, it's just another false economy.