|Some dare call it|
The Pearl Harbor conspiracy theory states that US President Franklin Delano Roosevelt had foreknowledge of the attack on Pearl Harbor and deliberately allowed the Hawaiian base to be attacked. No scholarly historical research supports the theory (though much pseudo-scholarship does). This is similar to the idea of a false flag operation in motive, but the attack is orchestrated by a real enemy and just allowed to happen.
These are the points generally brought up by the Pearl Harbor theorists:
 Lead-up to the attack
 FDR wanted war with Japan/Germany. He had been planning it all along
This point is actually a recycled criticism of FDR from the days he was actually in office. There was a strongly isolationist atmosphere in the US due to disillusionment with World War I and the Great Depression. Young adults of the Roaring Twenties were referred to as the "Lost Generation." With the economic collapse in 1929, people were far more worried about the state of their own country than international affairs. The Old Right, "Taft Republicans," and the GOP in general were hard-line isolationists (seriously). Conspiracy theorists often like to throw out quotes by FDR's opposition painting him as a warmonger.
However, FDR's arms build-up enjoyed bi-partisan support. The Army was so poor it was training its soldiers with wooden guns during the Depression. FDR was a Wilsonian and supporter of free trade, and so clearly came down on the side of the Allies with policies such as the Lend-Lease Act and the Four Freedoms. However, his stated policy was "all aid short of war" and had issued memos to the military making it known that they should not attempt to engage in any offensive action. Furthermore, FDR was far more concerned with Germany than Japan. This is similar to Truthers who cite Project for a New American Century documents. (It's merely circumstantial evidence, not definitive proof.)
 There were clear signs in radio transmissions intercepted by intelligence
This ignores the signal-to-noise ratio in the intelligence. Most messages were vague or not fully decoded and the ones that were more explicit were awash in a much larger sea of intelligence stating the opposite or having nothing to do with Pearl Harbor. There were also similar problems in intelligence collection to the ones that happened pre-9/11: Oftentimes, low-level intelligence officers would decode reports and then file them away in some dusty cabinet, never to be seen again. Communication between agencies wasn't perfect, or even that good, so a full picture of what the intelligence suggested never emerged. If anything, these conspiracy theories are a good argument for streamlining intelligence rather than arguments for a real conspiracy.
There is also the fact that intelligence gathered the week of the attack suggested that Japanese forces were most likely moving toward Thailand or Malaysia in that time frame. The Navy's phone taps in the Japanese consulate were found and removed about a week before the attack as well. Overall, the United States' military intelligence agencies had built up, by late November 1941, convincing intelligence that Japan was getting ready for a massive assault into Southeast Asia to seize the crucial natural resources it needed to continue its imperial ambitions, and the War and Navy Departments even sent out war-warning messages to major commands at the end of November. The problem was that nobody seemed to anticipate that Japan might want to take out a potential major obstacle to this operation — namely, the U.S. Pacific Fleet — first.
 The McCollum memo, outlining a strategy in the Pacific, proves war was the goal
More circumstantial evidence. Again, FDR, as well as his military advisors and naval officers in the Pacific, were wary of the growing Japanese empire and the possibility that it could strike the US. Every country draws up war plans for preparation for vast numbers of situations that may never occur. This sort of thing isn't unique to the run-up to Pearl Harbor. The memo itself, however, was not a blueprint for all-out war, but aimed at containment of Japan (though it does make a brief mention of provocation). In addition, it never went all the way up the chain of command to Roosevelt himself.
This assertion, by the way, still leaves open the question of what sort of incredibly clever and competent conspiratorial leadership would sacrifice a large portion of the Pacific Ocean fleet, at enormous military and economic cost, in order to begin a naval war with an already-aggressive Pacific power.
 December 7
 A Japanese midget submarine was sunk before the bombing began
This is an argument for incompetence rather than conspiracy. If FDR knew the attack was coming but the Navy didn't, this tells us nothing. If FDR knew it and had informed Navy higher-ups to ignore it, then we're getting into vast conspiratorial territory and assume that none of the informed Naval officers ever squealed, even in memoirs later in life. If everyone knew about it, it's an even more vast conspiracy and it wouldn't make much sense to fire on the sub if they wanted Pearl Harbor to be attacked. What actually happened was that one of the officers was informed of the incident and took his men off their posts to breakfast. In addition, the ship that reported the incident sent a message saying it had attacked a sub, not sunk it.
 Three aircraft carriers were out of port on war games. They obviously did this to save the carriers
The thing is, battleships were considered of primary importance in those days as carriers were untested weapons of war up to that point. If this were a conspiracy, letting the enemy take out such a huge portion of your fleet, even sans the three carriers, ranks as a massive failure at best and batshit crazy at worst. In addition — if it were a conspiracy — wouldn't it have been better to launch a counter-attack just as Japanese forces were about to hit Pearl Harbor? That way, it would still look like an attack on the US but the fighters and warships could be saved while the Japanese would be handed a defeat in the first battle of the war. What's more is that one of the carriers, the USS Enterprise was actually scheduled to be in port on Dec. 7 but was delayed in getting back, making this point even more nonsensical.
 The planes were sitting ducks outside of their hangars. They left them out in the open intentionally
The fighters were actually sitting on the tarmac outside the hangars to prevent an attack. Some of the Naval commanders were afraid of saboteurs breaking into the hangars and messing with the planes, so they left them out in the open where guards could watch them better.
 Japanese planes picked up on radar were ignored.
The enlisted men who were stationed at Opana Point, where the Japanese squadrons were detected, were fresh recruits who had never used the equipment before, which itself was still under construction. Conspiracy theorists claim that the admiral in charge, Husband E. Kimmel, ignored the transmission. In reality, it reached a lieutenant at Pearl Harbor, who mistook them for a squadron of B-17 bombers scheduled to arrive in the morning. Even if the lieutenant had been worried enough, the Army Air Force's early warning organization on Oahu was so skeletal that there was nobody in authority he could actually report to.
Kimmel was never made aware of this, and neither was his Army equivalent General Short. In addition, even if they were identified correctly, it's unclear if the naval base would have had sufficient time for preparations to fully fight off the attack.
 Listen to the Wolf!
In June 2001 then-Deputy Secretary of Defense Paul Wolfowitz made a Commencement Address at Michie Stadium in West Point. In this address, he states:
“”This year marks the sixtieth anniversary of a military disaster whose name has become synonymous with surprise — the attack on Pearl Harbor. Interestingly, that 'surprise attack' was preceded by an astonishing number of unheeded warnings and missed signals. Intelligence reports warned of 'a surprise move in any direction,' but this made the Army commander in Honolulu think of sabotage, not attack. People were reading newspapers in Hawaii that cited promising reports about intensive Japanese diplomatic efforts, unaware that these were merely a charade. An ultra-secret code-breaking operation, one of the most remarkable achievements in American intelligence history, an operation called 'Magic,' had unlocked the most private Japanese communications, but the operation was considered so secret and so vulnerable to compromise that the distribution of its product was restricted to the point that our field commanders didn’t make the 'need-to-know' list. And at 7 a.m. on December 7th, at Opana radar station, two privates detected what they called 'something completely out of the ordinary.' In fact, it was so out of the ordinary that the inexperienced watch officer assumed it must be friendly airplanes and told them to just forget about it.
This speech is archived by the United States Department of Defense, lending it more credibility. However, this doesn't conflict with the established facts behind the attack: a bunch of intelligence failures that never got its way up to high command in time. (And why would the DoD website have it widely available if it suggests something else?)
 Vastness of the conspiracy
As aforementioned, most versions of the theory would implicate a good chunk of the Pacific fleet's chain of command, up to and including, of course, FDR himself. The higher-ups stationed at Pearl Harbor would not only have to put their men's lives on the line, but also their own. And all without any of them letting anything leak, speaking up about it later, or objecting that the idea would be completely bonkers. This would be truly impressive considering the biggest conspiracy committed by the executive in American history was foiled by some fools who failed to tape over a door lock the right way.
The conspiracy theory originated during WWII among members of the America First Committee, something of an alliance of mostly far-left pacifists and far-right isolationists. The first work to posit the theory was a 1944 pamphlet by John T. Flynn, a paleoconservative journalist and head of the New York Chapter of America First. It has seen a revival in recent years by Truthers attempting to use the "FDR knew!" canard as precedent for 9/11 being a false flag operation.
- Skeptoid on Pearl Harbor conspiracy theories
- History of the Pearl Harbor conspiracy, Spinning Clio
- The Myths of Pearl Harbor, Pearl Harbor History Associates
- Records of the nine Pearl Harbor investigations
- Report Debunks Theory That the U.S. Heard a Coded Warning About Pearl Harbor, New York Times
- Pearl Harbor 'Winds Message' Controversy: A New Critical Evaluation, Committee for Skeptical Inquiry
- Debunking at Bartcop
- Dive-bombing FDR, Salon
- Pearl Harbor and the "back door to war" theory, Encyclopedia Britannica
- What Every Cryptologist Should Know About Pearl Harbor, NSA
- Day of Deceit by Robert B. Stinnett is probably the most popular work espousing this theory:
- ↑ See the memo here
- ↑ Indeed, during the interwar period the United States had drawn up plans for war with the British Empire, including an invasion of Canada. (It seems nobody remembered 1812.) Or Winston Churchill's fittingly-titled "Operation Unthinkable."
- ↑ A CV-6 fansite
- ↑ 2001 Commencement Address at the U.S. Military Academy, West Point, Defence.gov
- ↑ Transcript of "The Truth About Pearl Harbor" at — guess where — lewrockwell.com.