Fifty years ago, Martin Luther King Jr was shot dead in Memphis by a white segregationist and fugitive, James Earl Ray. Three years earlier, on 21 February 1965, the same fate had befallen Malcolm X, assassinated by members of the Nation of Islam.

In the decades since their deaths, they have come to symbolise polarised approaches to the question of racial equality. We can understand neither man, however, without recognising how their outlooks changed during their lives.

King’s insistence on non-violence is well known but his radicalism is often forgotten. In the mid-1960s, he took a decisive, and politically brave, stance against the Vietnam war, describing America as “the greatest purveyor of violence in the world today”. He became an advocate, too, of working-class struggles. In the weeks before his death, King was deeply involved in the Memphis sanitation workers’ strike, when rubbish collectors had taken industrial action for union recognition, better conditions and equal pay. To question poverty, he observed, is “to question the capitalistic economy”.

Malcolm X reinvented himself to an even greater degree. A petty criminal in his youth, it was in prison that he discovered the Nation of Islam and became a Muslim. By the 1950s, he had become became the NoI’s most effective public advocate, a searing voice against racism, but also, like all NoI members, deeply inflected with bigotry and misogyny.

He eventually broke away from the organisation in 1964. “There will ultimately be a clash between the oppressed and those that do the oppressing,” he told the Canadian TV host Pierre Berton, “but I don’t think that it will be based upon the colour of the skin.”

By the end of their lives, the two men had drawn closer to each other’s views. Their differences were, however, real and spoke to an inherent tension within the struggle for racial equality. King expressed a universalist ethos – that racism was intimately bound with the social structures of America and that challenging it required the creation of broader social movements.

Malcolm X was sceptical both about the possibilities of such movements and about King’s call for moderation to win wider support. He insisted that blacks had first to organise on their own and to protect themselves “by any means necessary”. It was a vision that inspired the radicalism of the Black Panthers and the Black Power movement. But there was also something deeply conservative in his stress on moral reform and individual uplift as the route to a more just world.

Fifty years on, the racial landscape in America is very different. The White House has been home to an African American president. Yet in many ways little has changed. Median white family income in 1963 was seven times that of non-whites; in 2016, it was 6.6 times that of African Americans. Much has got worse. The proportion of the prison population that is black has nearly doubled since 1968; mass incarceration of African Americans now constitutes, in the words of civil rights lawyer Michelle Alexander, the “new Jim Crow”.

What has most regressed, perhaps, lies in the terrain of politics. The tension between King and Malcolm X remains, though is expressed differently. On the one side stand liberal universalists, espousing a “colour blind” philosophy, on the other, those who cleave to a politics of identity.

In the 1960s, the tension between the two approaches was fruitful. It created a dialogue about how to change social structures and people’s minds that shaped the political journeys of both King and Malcolm X. They were a fusion of conservative and radical. In the context of wider social ferment, it was radicalism that came to the fore.

Today, though, both sides have been shorn of radical aspirations. The “colour blind” approach is too often an excuse to ignore the social and economic realities of black people’s lives. The politics of identity expresses a pessimism about social change, advocating instead a retreat into sectional silos. The result is an acceptance, in the sardonic words of African American academic and activist Adolph Reed Jr, that “a society in which 1% of the population controlled 90% of the resources could be just, provided that roughly 12% of the 1% were black, 12% were Latino” and so on.

Detached from wider movements for social change, the radical legacies of King and of Malcolm X have largely been interred. The conservatism lives on.

• Kenan Malik is an Observer columnist