ARGUMENT 1: THE US KNEW
The popular myth of Pearl Harbor goes like this. In 1941, the United States was keeping well out of World War Two, and basically minding its own business, when Japan mounted a shocking surprise attack on the American naval base at Pearl Harbor. Thousands died, President Franklin D. Roosevelt declared it a "date which will live in infamy", and America was reluctantly forced to enter the war.
But the real story isn't as simple as that. The United States was by no means a neutral observer of WW2. Roosevelt was already working as a firm ally of Britain against the Nazis, pushing through legislation that allowed his ostensibly neutral nation to supply the British with munitions and other war materials.
On top of that, the Roosevelt administration had taken a firm stance against Japanese aggression in the Far East, and had essentially waged a form of economic war by placing strict trade embargoes on Japan.
Roosevelt knew war was inevitable, and that - given the scale of the evil being unleashed by the Axis powers - war was necessary. As US Rear Admiral Frank E. Beatty recounted, "it was the desire of President Roosevelt [...] that we get into the war, as the Allies could not win without us." A reason, or pretext, was needed to join the global battle against fascism. That pretext was Pearl Harbor.
Early in 1941, in an episode straight out of something from spy fiction, a US embassy staffer in Tokyo was standing in line at a bank when he was approached by the Peruvian envoy to Japan, who told him he had it on good authority an attack on Pearl Harbor was being planned. The staffer passed the warning onto his superiors at the US. Later, a spy codenamed "Tricycle" also passed on information about an attack on Pearl Harbor.
Even more damning is a written account by Henry L. Stimson, the US Secretary of War, who described how Roosevelt pondered "how we should manoeuvre [the Japanese] into the position of firing the first shot without allowing too much danger to ourselves."
If by these means Japan could be led to commit an overt act of war, so much the better.
That's right: the US president literally discussed provoking Japan into a first strike. There was even an official document detailing a plan along these lines. Known as the McCollum memo, it was written a year before Pearl Harbor and outlined a strategy for dealing with the problem of Japanese expansion, and included the shocking statement: "If by these means Japan could be led to commit an overt act of war, so much the better."
When you consider the sheer weight of circumstantial evidence - the specific warnings about the attack, the pro-war political imperative of Roosevelt, and the planning that went into the imminent war against the Axis - it seems far more likely than not that the US allowed the attack on Pearl Harbor to take place.
ARGUMENT 2: IT WAS A SURPRISE ATTACK
There are two giant problems with the pro-advance-knowledge argument. First, it's all circumstantial evidence, none of which would stand up in a court of law. Second, all of this circumstantial evidence can be decisively refuted or explained.
Take the issue of the McCollum memo, the "smoking gun" of Pearl Harbor by conspiracy theorists. Eugene Jarecki, author of The American Way of War, puts it best: "No single memo by a mid-level functionary should be given too large a role in the shaping of a president's policy." Indeed, there's no evidence the memo was even seen by Roosevelt.
Plus, conspiracy theorists fail to understand that, in the words of military historian Dr Conrad Crane, "the McCollum proposal itself was designed to prevent war, not provoke it. A close reading shows that its recommendations were supposed to deter and contain Japan. There is an offhand remark that an overt Japanese act of war would make it easier to garner public support for actions against Japan, but the document's intent was not to ensure that event happened."
It should also be said that there were plenty of other competing plans and strategies flying around at the time. In 1941, a certain senior official named Brigadier Leonard T. Gerow stated, "one of our present major objectives [is] the avoidance of war with Japan". Clearly nobody told him about the vast sinister conspiracy to trick the public into supporting just such a war.
As for the apparent warnings of an attack in Hawaii... well, we're talking about the opening year of World War Two, a time of rumours and uncertainty, when all kinds of intelligence was flying back and forth. What's more likely - that some warnings were fumbled and ignored, or that President Roosevelt orchestrated a vast, sprawling conspiracy to let thousands of Americans perish in a fiery onslaught?
Yes, Roosevelt was pro-war. And yes, he regarded the Axis powers as an existential threat to democratic civilisation. But we enter the realm of paranoid fantasy if we think that he or his senior advisors believed sacrificing a major naval base was the best way to join the Allies.
If they were not surprised by the news from Pearl Harbor, then that group of elderly men were putting on a performance which would have excited the admiration of any experienced actor
The legendary crusading journalist Edward R. Murrow saw first-hand how stunned the top officials were by the attack. "If they were not surprised by the news from Pearl Harbor, then that group of elderly men were putting on a performance which would have excited the admiration of any experienced actor," he reported. "There was amazement and anger written large on most of the faces."
And with good reason. They may have known SOMETHING was coming, but they did not foresee an attack as audacious and bloody as the one on Pearl Harbor.