When academic philosophers achieve wider public renown it is, more often than not, because their work generates a certain amount of outraged controversy. Richard Rorty was no exception here, though this was one of the few ways in which he bowed to convention.

Rorty described his career as a decades-long search to find out “what, if anything, philosophy was good for”. His answer was uncompromising: any effort to discover truth was wasted. “There is no basis for deciding what counts as knowledge and truth other than what one’s peers will let one get away with.” Philosophy should instead concern itself only with what was helpful to everyday life, such as supporting modern liberal democracy.

In this he took forward the American philosophical tradition of pragmatism – developed around the turn of the last century by John Dewey, William James and others – pushing it towards postmodernism.

But his notoriety rested on the casual way in which he dismissed millennia of philosophical heritage, as well as on his denial of objective truth. He took his iconoclasm beyond the academy in an array of smartly phrased newspaper and magazine articles.

This made him hugely influential in philosophy, literary theory and beyond, but made him enemies on both the political Right, who saw him as antirational, and the Left, who were irked by his cheerful dismissal of radicalism.

Richard McKay Rorty was born in 1931 in New York to two writers, communists whose support for Trotsky was so deep that they sheltered one of his secretaries.

The effect that his parents’ politics had on Rorty was profound. To him, Trotskyism was the faith of his parents’ household in the same way that Christianity might be for another. He later reflected that by the age of 12 he knew “that the point of being human was to spend one’s life fighting social injustice”. The Russian Revolution and its betrayal by Stalin were “what the Incarnation and its betrayal by Catholics had been to the precocious little Lutherans four hundred years before”.

Rorty also remembered having “private, weird, snobbish, incommunicable interests” as a boy, saying that he sent the newly enthroned Dalai Lama a present. He had an obsessive fascination with the wild orchids of northwest New Jersey and he remained a lover of the outdoors, particularly bird-watching, throughout his life.

Rorty’s eccentric intelligence was quickly recognised and he entered the University of Chicago at the extraordinarily young age of 15. “I escaped from the bullies who regularly beat me up on the playground of my high school, bullies who, I assumed, would somehow wither away once capitalism had been overcome.”

Rorty initially turned to Christianity to find absolute truth but found his “prideful inability” to believe anything he was saying in confession led him back to philosophy. In his first summer at university he began to read Plato, whose concept that “virtue was knowledge” seemed to be exactly what Rorty was looking for. It appeared to celebrate academic prowess “without the humility that Christianity demanded and of which I was apparently incapable”. Furthermore it seemed to offer total argumentative power over others and a mental state in which all doubts would be stilled.

From the age of 15 until 20, when Rorty began his PhD at Yale, he tried to follow this route. However, he gave up the quest because he did not find it coherent without the existence of a God that he could not believe in.

After receiving his doctorate in 1956, he was drafted and spent two years in the US Army. In 1961, after two years teaching at Wellesley College, he moved to Princeton where he spent the next 20 years. Building on the concepts of pragmatism set out by his hero, Dewey, he argued that instead of seeking ideas which correspond to some fundamental reality, we should settle for ones which help us carry out practical tasks and create a fairer and more democratic society. In 1981 he won one of the first MacArthur Foundation “genius grants”.

In his most famous book, Philosophy and the Mirror of Nature (1979), he contended that theoretical systems only provide descriptions of human behaviour in a given historical period. The book, along with others such as Contingency, Irony and Solidarity (1989), proved to be enormously influential. Rorty noted that his initial hope of achieving a single vision of an historical truth by becoming a philosopher had ultimately proved to be “a self-deceptive atheist’s way out”.

Rorty did not regret becoming a philosopher though. It prevented him, he thought, from imagining that there was “a luminous synoptic vision” of the truth. His own vision of the truth, like Dewey’s, was of a community in which everyone thinks that it is human solidarity, rather than knowledge of something not really human, that mattered.

Happily he noted that “the actually existing approximations to such a fully democratic, fully secular community now seem to me the greatest achievements of our species”.

Rorty’s dismissal of analytic philosophy and other main-stream schools drew the ire of fellow academics, whom Rorty could delight in teasing – he once defined an academic philosopher as “someone with the ability to take seriously the opinions of Immanuel Kant”.

But his attacks on the concept of knowable truth drew more serious criticism from those who argued that it ignored the obvious achievements of science, downgraded the status of human rights and left the philosopher with no answer to the Holocaust-denier.

Rorty did not back away from these charges, and his public defence of his stance earned him a global reputation. “There are no transcendent answers,” he insisted. “Each of us must reach our own conclusions about life, and try to respect the differences among us.”

He was a major influence on postmodern thought and in 2005 he was named as one of the world’s top 100 public intellectuals by Prospect magazine.

Despite his epistemological radicalism, Rorty’s own political views were never extreme, and some suggested he did not take himself entirely seriously. Rorty himself held up the philosophical “ironist” as a model of philosophical discourse.

Characteristically, Rorty took a close interest in conflict. He thought that when groups found themselves at odds with each other, philosophical discussion would usually not help in resolving their differences. It would never “convince bullies not to beat him up” or “capitalists to cede their power to a co-operative, egalitarian commonwealth”.

Groups had very different vocabularies, he suggested, and the best one could do was to show the other side how it looked from your point of view while at the same time imaginatively identifying with the other’s pain.

It was, then, the artist and the poet who could best elicit peace between groups by demonstrating that there was vulnerability to which all human beings can relate. Rorty’s written style evolved as a result. He moved increasingly from the philosophical and argumentative to a narrative mode, and in 1982, frustrated by discipinary constraints, left his tenured position at Princeton to become a professor of humanities at the less presitigious University of Virginia. In 1998 he became Professor of Comparative Literature at Stanford University.

Rorty’s later works showed an irritation with the academic Left, which had refused, as he saw it, to take part in day-to-day political life. Instead, it had adopted a sneering, spectatorial position, offering radical critiques of society without practical proposals as to how to improve it.

Furthermore, while still maintaining his socialist ideology, he felt forced to admit that ultimately Lenin and Trotsky did more harm than good.

Rorty was also unashamedly patriotic and saw national pride in America as a good thing, so long as it was not turned into self-aggrandisement or brutal enthusiasm for military might.

He contended that “despite its past and present atrocities and vices”, America was “an example of the best kind of society so far invented” and that “welfare-state capitalism” was the “best we can hope for”. For many on the Left in America, his views were anathema.

However much Rorty criticised aspects of the Left, his most scathing attacks were always reserved for the Right. He made frequent gibes at the “orthodox”, those who thought that “hounding gays out of the army promotes traditional values”. To Rorty these were “the same honest, decent, blinkered, disastrous people who voted for Hitler in 1933.”

The progressive Left then remained for Rorty the only “party of hope”. In his book Achieving our Country, he hailed the Left as the key element in the reduction of “sadism” in society, arguing that the casual infliction of humiliation had become much less socially acceptable.

He praised, too, the adoption of the “politically correct”, believing it had been a civilising force on America, noting that the tone in which “educated men” talked of blacks and women was very different from what it had been before the Sixties.

Rorty is survived by his wife, Mary, their son and daughter, and a son from his first marriage.

Richard Rorty, philosopher, was born on October 4, 1931. He died of pancreatic cancer on June 8, 2007, aged 75