KEY POINTS:
There's a tendency to assume that the left occupies the moral high ground.
After all, the progressive side of politics is about change while conservatism, by definition, seeks to preserve the status quo. The left is idealistic, the right sceptical, believing that human beings are flawed, self-interested creatures with limited capacity for improvement. The left is youthful and open-minded, the right prudishly middle-aged.
Historically, the right has been associated with privilege, authoritarianism, bellicose nationalism, and exploitation, and the left with the catchcry of the French revolution: Liberte, egalite, fraternite. The left often appears to be an unruly but passionate mass movement, the right an alliance of hierarchical institutions. The left, it could be said, is entranced by ideas, the right by money. The left believes in the safety net, the right that greed is good.
For the baby boomer generation, this assumption was reinforced by the Vietnam War and Watergate. Images of the last US military helicopter heaving itself off the Saigon embassy roof and Richard Nixon sloping across the White House lawn to chopper into ignominious exile like some ousted banana republic generalissimo evoked a sense of physical and moral exhaustion.
And now history repeats itself with America, under a President who embodies the worst features of contemporary American conservatism, notably blinkered ignorance fortified by evangelical Christianity, once again bogged down in a war of occupation thousands of kilometres from its own borders.
On closer examination, however, the left's hold on the moral high ground is distinctly shaky. For much of the 20th century, the democratic left found it extraordinarily difficult to condemn the despotic, murderous reality of communism in practice in the Soviet Union and China.
Even when Robert Conquest's forensic expose The Great Terror (1968) provided overwhelming evidence to show that Stalin was responsible for the deaths of some 20 million of his compatriots, it was widely disbelieved or dismissed as propaganda.
The consensus among historians who followed in his footsteps was that he had, if anything, underestimated the slaughter. When Conquest was preparing an updated version, novelist Kingsley Amis suggested the new title should be I Told You So, You F******g Fools.
There's a persuasive reason why the Nazis' crimes against humanity should be deemed more monstrous than those of the Communists.
Nazism had no purpose or justification for the destruction of the Jews beyond the gratification of pathological race hatred while its wider purpose was simply blood and empire - building the thousand-year Reich.
The crimes committed in the name of Marxism - and the denial of them - are testimony to the blinding power of the Big Idea, the blueprint for a better world. As Conquest said, "Not even high intelligence and a sensitive spirit are of any help once the facts of the situation are deduced from a political theory, rather than vice versa."
But in the end you keep coming back to the death toll. Shouldn't that speak for itself?
One of the curiosities of this debate is that while sections of the left have resorted to moral relativism to downplay, excuse, or defend reprehensible actions by anti-Western governments and groups, they give the West no such leeway, judging it in strict black and white terms.
Left-wing pin-ups boys like Noam Chomsky, Robert Fisk and John Pilger don't do grey; never have, never will. They operate on the basis that the West, led by America and Israel, is fundamentally venal and responsible for most of the ills in the world and all the ills in the Middle East.
It's a short step from believing that to accepting that Islamist terror is a regrettable but understandable response to intolerable treatment, a step many liberal-minded people have been prepared to take.
This despite the fact that al Qaeda and its affiliates have made it abundantly clear that their cause and objectives are messianic rather than geo-political or economic. They're driven by a desire to impose a fundamentalist form of Islam complete with Sharia law and a hatred of our godless decadence (what we see as secular tolerance) rather than, say, the plight of the Palestinians or anti-globalisation.
The central thesis of English journalist Nick Cohen's recent book What's left: How Liberals Lost Their Way is that the democratic left, for whom anti-fascism was once as natural as breathing, no longer recognises fascism even when it lays its cards on the table or revels in the carnage of a mass murder. And because they won't look the beast in the face, they think - like Neville Chamberlain at Munich - that they can appease that which can't be appeased.
