Over the long-term, the importance of national borders will invariably decline. For those with a rudimentary understanding of economics, their importance is already negligible. Capital is highly mobile in today's world and therefore in order to deal with everything from tax avoidance to organised financial crime, governments must act globally.

Even for those who don't have to worry about monetary policy, the writing should be on the wall. Who can look at the European migrant crisis and pretend mass migration due to war or famine is more effectively dealt with by individual nation states bellowing at each other?

If not a borderless world, then a world in which borders mean something very different is around the corner. But the left is in big trouble if it forgets that for most voters the nation state remains central to how they think about things such as welfare and public services.

Labour leader Jeremy Corbyn will this week make a foray into the debate over the right of European migrants to claim benefits in Britain. He is expected to attack David Cameron's negotiation of an "emergency brake" on benefits for new migrants as potentially discriminatory. The proposed emergency break is a four-year benefits freeze for incomers but largely centres on restricting migrants' access to in-work tax credits (new migrants are already banned from claiming out-of-work benefits such as Jobseekers' Allowance).

'Scrounger' or claiming Working Tax Credits - not both

Introduced by Gordon Brown in 1999, Working Tax Credits are available to working people on low pay to help make ends meet. The basic amount goes up to £1,960 a year. Their recipients are a million miles away from the right-wing caricature of layabouts who scrounge off the state. Working Tax Credits are, as the name suggests, only available to those in employment. A person is either a scrounger or they are claiming Working Tax Credits. They cannot be both.

As far as migrants go, it is also important to recognise the net contribution they make to the British exchequer. According to a recent study by University College London, European migrants paid in £20bn to UK public finances between 2000 and 2011. The tabloid headlines about EU migrants flocking to Britain to sign on for £57.90 in Jobseekers' Allowance are invariably fictitious or atypical.

As for the problem of migrants from Europe sending child benefit to their families back home, in the grand scheme of things the amount involved is a drop in the ocean. The annual figure is around £30m – a tiny sum when set against the Department for Work and Pensions' annual budget of over £150bn.

Cameron's emergency brake was probably conceived as a piece of red meat to appease the immigration-loathing Tory backbenches. But to paraphrase George Orwell, just because Tory MPs like the policy it does not mean that it is wrong.

Discrimination issues

Let's start with the basics. The welfare state in this country is paid for out of the taxes of around 40 million British people. It is thus not unreasonable to argue that British citizens should stand at the front of the queue ahead of the 503 million residents of the European Union.

'But is it not wrong to discriminate against migrants in the welfare system?' you might ask.

This word is being thrown around by opponents of Cameron's proposal as if it were necessarily a bad thing. Yet states "discriminate" in favour of their own citizens in one way or another every day.

You will be discriminated against if you try to claim a British passport and are from another country. You will be discriminated against if, as a British citizen, you travel to Spain and try to vote in that country's parliamentary elections. You will be discriminated against if you roll up in France and try to sign on for unemployment benefit.

Distinguishing between those who should and should not have the right to draw on the welfare state – a welfare state built up by British workers (yes, with the help of economic migrants) – is the only way progressives will ever maintain public support for it. This does not mean engaging in the anti-migrant rhetorical baggage beloved by the tabloids.

Migrants living and working in Britain should for the most part expect the same benefits as British citizens. But it does not seem unreasonable to suggest that, if you are unable to get a job in Britain that pays enough money to live on, then perhaps this country is not the place for you.

Vote to leave

An unwillingness on Labour's part to accept that there should be limits on what new migrants can draw in benefits risks jeopardising Britain's future in Europe. The European referendum is not like a general election where Labour votes pile up pointlessly in safe seats. Every vote in the referendum has equal weight.

A significant number of Conservative voters will invariably vote to leave. Ensuring Labour voters turn out on referendum day will therefore take on a new importance. On the back of an election defeat in which voters decided Labour was too soft on welfare and immigration, opposing Cameron's emergency brake would be a suicide strategy.

Immigration is one of the biggest issues fuelling resentment of the EU among the electorate. Much of this is sadly down to the misinformation spread about immigration by sections of the media. A significant number of the answers to public concerns about immigration are also found on recognisably progressive territory.

The Tories have failed to take on employers who pay poverty wages and buy-to-let landlords who cram migrants into shoddy accommodation. Labour has another easy hit on the Tories for talking about "integration" while simultaneously cutting public expenditure on English classes.

With ongoing Conservative attempts to chip away at the European Social Chapter, there are therefore a whole number of important things Labour must fight for in Europe. Unfortunately for Corbyn, asking struggling British workers to top up the wages of EU citizens who have come to Britain of their own volition isn't one of them.