There is one aspect of the offensive campaign by the Daily Mail against Ralph and Ed Miliband that has particular significance: the implication that socialism can be treated as a dirty word and that its adherents "hate Britain". I would argue both that socialism is of crucial importance and that the future of Britain depends upon its continuing influence. It is true, though, that for much of the population, the connotations of the term are no longer positive. How has this happened?

One important factor has been the successful attempt by its opponents to associate socialism and, still more, Marxism, with the most negative forms it has ever taken: the gulags of the Soviet era have therefore always loomed large in anti-socialist propaganda. It appears to make no difference that numerous Marxists, including Ralph Miliband, have been deeply critical of the Soviet system and passionately committed to democracy.

Ed Miliband is no Marxist and it is difficult to make a credible link between him and Stalin, so his version of socialism is depicted as inefficient, utopian, intent on creating a "big state", indifferent to individuals and controlled by the unions. This negative discourse seeks to hide the many positive aspects of socialist values and to stifle debate about alternatives.

Download the new Independent Premium app Sharing the full story, not just the headlines

An understanding of socialism must start by recognising that it has been extremely diverse, from small-scale "bottom-up", participatory co-operative communities to "top-down" centralised state dictatorships. Any serious attempt to promote the doctrine needs to draw on this diversity, while learning from both its successes and failures. From this can its key values be developed.

The first value is a commitment to the creation of an egalitarian society. Socialists might not all agree about how or how far inequality can be eradicated, but no socialist would defend the current inequalities of wealth and power. And this is related to a critique of capitalism: the belief that it is a system that necessarily leads to massive wealth and power among a relatively small minority at the top and a cycle of deprivation that constrains the lives of a far larger number at the bottom.

Second, socialism believes in an alternative egalitarian system based on greater social solidarity and co-operation. Socialists reject the notion that individual self-interest and competition are the sole motivating factors in human behaviour and hold that other human characteristics may be fostered by a co-operative society. This has implications for how we value the environment, define the public sphere and respect other people.

Finally, socialists are optimistic that it is possible to make significant changes. They accept that inequalities are deeply embedded in structures both within and beyond individual societies, but they do not accept an attitude of passive resignation to the status quo.

Ralph Miliband, following the Italian Marxist Antonio Gramsci, hoped to create a socialist "common sense" to reverse the position where capitalism is seen as the only possible system. He concluded his final book, Socialism for a Sceptical Age (1994):

"In all countries, there are people, in numbers large or small, who are moved by the vision of a new social order in which democracy, egalitarianism and cooperation – the essential values of socialism – would be the prevailing principles of social organization. It is in the growth in their numbers and in the success of their struggles that lies the best hope for humankind."

There is certainly potential to reclaim this kind of vision as an integral part of British life and society.

Michael Newman is emeritus professor of politics, London Metropolitan University and author of 'Ralph Miliband and the Politics of the New Left'