The propaganda onslaught against Britain's public service workers and their unions is reaching fever pitch. David Cameron says Wednesday's strikes are the "height of irresponsibility" and Francis Maude claims they will inflict "huge damage" on the economy. Their cheerleaders in Rupert Murdoch's Sun insist the walkouts – by care workers, refuse collectors, firefighters, teachers and nurses – to defend their "golden pensions" are "reckless" and "selfish". The Mail calls their leaders "antedeluvian monsters".

Media oligarchs who no one voted for and refuse to recognise unions themselves, along with ministers elected by less than a quarter of the electorate, have the cheek to challenge public service workers' right to strike because some postal ballot turnouts were below 50%. Most of the public, according to the latest Comres poll for the BBC – especially women – disagree and back the strikes. But it's not surprising if some public service workers, with "gold-plated" pensions that average £6,500 a year and £4,000 for women, feel daunted by the scale of official hostility to their exercise of the basic democratic right to withdraw their labour.

So here are five reasons why public service workers are right to strike this week:

Industrial action is the only way left to defend pensions

The government is trying to make most pay more and work longer for less, even after this month's modest concessions. That isn't to fund pensions because people are living longer, but to help pay off the deficit run up to bail out the banks and the crisis they triggered. The 3.2% contributions hike is a tax on a workforce whose living standards have already been heavily squeezed by repeated pay freezes. Pensions aren't a perk, but deferred pay. Protecting pay and conditions is what unions are for.

The strikes are in defence of public services, not just their workers

By driving down pay, pensions and conditions in the public sector, the government will also force down the quality of services it provides. That's the reason the headteacher Cameron praised so effusively for refusing to take industrial action in June plans to strike on Wednesday. As Sue Foster-Agg put it at the weekend: "My concern is that they are not going to attract the best people into the teaching profession." Far from helping workers on worse or non-existent pensions in the private sector (where tax relief is rigged to support the better off), attacking public pensions will simply speed up a race to the bottom for all.

Protection of public pensions will support, not damage, the economy

The biggest problem the economy faces right now is a lack of demand and investment. Tomorrow's forecasts will show the government's cuts programme isn't working and is tipping us towards recession. Boosting public sector pension contributions and reducing pension entitlements, on top of falling real pay, can only make that worse. Far from damaging the economy, the more successful the public service unions are in defending their living standards – and minimising cuts – the better for the economy.

Ministers won't shift because of a good case – but under pressure

The argument about pensions and cuts won't be won by argument alone. The concessions already made on pensions wouldn't have happened had more than two million public service workers not been balloted for industrial action. The larger Wednesday's walkout, the more likely ministers are to shift further. That's why union members on average earn 15% more than the rest. Strikes are also a reminder of who actually does the work that matters most to our lives – and a demonstration of democratic strength in the workplace.

Graphics: with thanks to Alistair Davidson

Walkouts are a direct challenge to the wealth grab of the 1%

The government's pension raid is an attempt to make public service workers pay for the havoc wreaked by wealthiest, whose incomes continue to soar. A crucial factor in accelerating inequality over a generation has been the weakening of trade unions. Between 1975 and 2008 the share of wages and salaries in national income fell from 65% to 53%, while corporate profits swelled. Track the decline in union membership against the slice of the national cake taken by the richest 1% (as the graph above does) and the relationship between the two couldn't be more obvious. A powerful union revival on Wednesday can start to turn that tide.