Carey told the New York Times the PEN American Centre had stepped beyond its traditional role, which he said was protecting freedom of expression against oppressive governments. In doing so, it had rewarded France's "cultural arrogance" towards its Muslim underclass.
"A hideous crime was committed, but was it a freedom-of-speech issue for PEN America to be self-righteous about?" asked Carey.
"All this is complicated by PEN's seeming blindness to the cultural arrogance of the French nation, which does not recognise its moral obligation to a large and disempowered segment of their population."
Michael Ondaatje, Francine Prose, Teju Cole, Rachel Kushner and Taiye Selasi are the other boycotters.
The letter signed by Oates condemned the murders but blamed the magazine for attacking a "section of the French population that is already marginalised, embattled, and victimised". To parts of French society - "a population that is shaped by the legacy of France's various colonial enterprises, and that contains a large percentage of devout Muslims" - Charlie Hebdo's cartoons of the Prophet "must be seen as being intended to cause further humiliation and suffering", it said.
"This PEN award is merely the latest instance in the now-rampant free expression of gentlemanly Islamophobia," wrote American essayist Eliot Weinberger in a blog on the leftwing London Review of Books.
PEN said it would press ahead with the ceremonies, which will see its Freedom of Expression Courage Award handed to Gerard Biard, Charlie Hebdo's editor-in-chief, and essayist Jean-Baptiste Thoret.
"Only a handful of people are willing to put themselves in peril to build a world in which we are all free to say what we believe," PEN said.
"The 'assassin's veto' over speech has become a global phenomenon in recent years and, even more vividly, in recent months, when we've seen killings not just in Paris but also in Copenhagen and Bangladesh."
Carey, Oates and the others have drawn fire from other intellectuals, led by British author Salman Rushdie, who spent years under police protection over death threats for his novel The Satanic Verses. The boycotters are "just six pussies, six authors in search of a bit of character", Rushdie said.
He accused them of being "fellow travellers" of jihadists who wanted to impose theocracy at gunpoint - an argument shared by Nick Cohen in Britain's Spectator magazine.
"They not only go along with the terrorists from the religious ultra-right but with every state that uses Islam to maintain its power," wrote Cohen. "They can show no solidarity with gays in Iran, bloggers in Saudi Arabia and persecuted women and religious minorities across the Middle East, who must fight theocracy." Cohen added: "They have no understanding that the enemies of Charlie Hebdo are also the enemies of liberal Muslims and ex-Muslims in the West. In the battle between the two, they have in their stupidity and malice allied with the wrong side."
In France, some wonder if Carey and the others have failed to cross a cultural barrier. Charlie Hebdo styles itself as the inheritor of a French satirical tradition dating back to Voltaire, when courageous writers let rip at anyone powerful, pompous or tyrannical, regardless of faith, politics or social status.
According to a count of 523 front pages published by Charlie from 2005 to 2015, just 38 satirised religion, of which 21 targeted Christianity, 10 attacked two or more religions but only seven took aim at Islam, Le Monde reported on Thursday. Of the rest, 336 had politicians in their sights, while business chiefs, celebrities or intellectuals were the other targets.
"French satire is deeply rooted in a political model based on verbal violence against every form of domination. It is crude, rude and rough but it has been a part of the French political system for the last three centuries," Cyrille Bret, a professor at the Sciences Po university in Paris, told the Weekend Herald.
The Charlie killings, noted Bret, had revived French defence in freedom of speech and secularism - the policy of state neutrality in matters of religion which includes a ban on religious symbols and proselytising in schools, courts and public offices.
