IN THE Los Angeles Times a few weeks ago, the middlebrow American eclecticist and historian Mark Kurlansky told his readers that a new piece of writing “may be one of the most important books you will ever read”. The work was Human Smoke, by the novelist Nicholson Baker, a factual venture into the origins of the Second World War. Human Smoke, Kurlansky said, demonstrated “that World War II was one of the biggest, most carefully plotted lies in modern history”.

Kurlansky was not talking about Hitler and his various inventions or provocations that permitted him to occupy several neighbouring states. The lies, according to Kurlansky, were told by the leaders of the democracies, especially Roosevelt and Churchill. Baker had shown, “step by step, how an alliance dominated by leaders who were bigoted, far more opposed to communism than to fascism, obsessed with arms sales and itching for a fight coerced the world into war”.

In fact Baker's book does not “show” or “demonstrate” anything in particular about the causes of the war, consisting, as it does, of hundreds of snippets of speech, diary extracts and single lines from newspaper reports, combined into a chronological narrative. He dedicates the book to the memory of US and British pacifists. “They tried to save Jewish refugees, feed Europe, reconcile the United States and Japan and stop the war from happening. They failed, but they were right.”

The opponents of Baker's world view were, primarily, men such as Roosevelt and Churchill, who came to regard armed conflict with fascism as practically inevitable. In Human Smoke Churchill emerges as an all-weather warmonger with a penchant for bombing civilians, his bloodthirstiness made worse by the superb rhetoric in which it was couched. This is exactly the Churchill depicted by Goebbels and Stalinist propagandists. It is, of course, partly true. It is also substantially untrue.

I was slightly surprised that, when he was in London last month, Baker agreed to meet me. I thought that his publishers might have warned him about a possible hostility towards his underlying thesis. But Baker, 6ft4in, florid, white-haired and tweedy, was courteous and brave. I liked him a lot.

Why had he written this book? “We can all agree that Hitler was the worst guy ever born, but I had a puzzlement at the West's response.” He means that he was puzzled at the West's belligerence towards Hitler. He felt that the proximity of war brought the worst leaders - the “sabre-rattlers” - to the fore. “Then I had the Iraq war. I was in Washington when the Pentagon was flown into. I said, ‘I just hope we're not bombing some place any time soon'.”

Baker denies believing that there is a moral equivalence between the Axis and the Allies. But the Second World War was constantly used against modern peace movements as “the grand counter-example, the war that had to be fought”, and he questions whether that is true.

Was he saying that America shouldn't have supported Britain with military aid in 1940? Not with bombers, he replied. There were good opportunities for peace with Hitler that might have avoided the suffering of the war - and even meant no Holocaust. “Let's just go to 1940. We reach agreement and see what happens. It allows the refugees to escape. Potentially things happen in Germany which are more to our liking. There were moderate factions around Hitler who were deeply distressed by his irrational urges. Things could have changed in Germany.

“During the Second World War there's the greatest state-run programme of extermination ever. And I think you just have to look at the fact that those two things are co-terminous.” In other words, Churchill's obduracy and Roosevelt's war hunger gave rise to the conditions in which Hitler could murder the Jews.

“Why the fuck was the war fought? Why? It wasn't a war to help the Jews, it was fought instead of helping the Jews. It was easier to raise massive armies and air forces than to lift quotas.”

I pointed out that Hitler had long been determined to extinguish Bolshevism and occupy large parts of the Soviet Union - with the millions of Jews living there. There was, Baker agreed, “a fantasy” of conquering Russia. “But what turns a megalomaniac's fantasy into something a whole state mechanism supports? The stress and distortions and witnessed ruin of war becomes the umbrella under which radicalism shelters.”

Me: “We couldn't have lived in the Europe that would have been created by not resisting Hitler in that way.”

Baker: “It's easy to think of Hitler as a perpetual motion machine, a man who is not a man, but an evil force that will live for ever. But he was a sick man. He had a tremor. His life span would have been short. But let's say he would have lived till 85, I can't imagine that a Germany at peace, a prosperous Germany, would have tolerated a loutish, hate-filled leader for long.”

Me: “Isn't the truth that the Germany that emerges from the war is better than the Germany that went into it?”

Baker: “The notion that a regime is more democratic than a horrific dictatorial regime is, of course, of interest, but the fact is that millions of people died, cities were laid waste...”

So, taking the case of US opposition to Japanese action in China, I said that I am glad that the Americans helped the Chinese. There was a pause. “I guess we have a fundamental disagreement. The Japanese bombing of the Chinese cities was avoidable.

“The Japanese wanted to occupy Manchuria. If they had simply occupied Manchuria, those people wouldn't have died. What action would have involved the least amount of suffering? The bombing of London was one of the most horrible things that could possibly have happened.”

I told the agreeable Mr Baker that I would far rather have seen St Paul's and every historic church in the country blown up than live for 25 years under fascism. “That's when it gets close to that Churchillian noble-sounding rhetoric,” Baker replied. It was a moment of mutual incomprehension.

You have, I think, to feel very strongly about Iraq and George W.Bush to need to construct a world in which all the Jews would have gone to Madagascar, or Tanganyika, there to dwell in peace; Nazi Germany would have run Europe, mellowing out with prosperity and conquest and somehow avoiding war with Russia; Hitler would have died early to be replaced by some cuddlier transitional figure; and in the Pacific Japan would have enjoyed its dominion over its hemisphere. Which would have been tough for the Chinese, but then, when was it not tough for the Chinese?

Human Smoke by Nicholson Baker
Simon & Schuster, £20; 576pp Buy the book here

Times Recommends

• 10 things you should avoid in hospital (unless there really is no option)
• Exclusive: Philip Pullman's essential reading list
• The White War by Mark Thompson