I've been reading Lundstrom's The First Team. I'm almost halfway through, but there is a definite trend emerging. Yes, the American aviators over-estimated their kills, but they usually involved one plane engaging the same plane as another had already engaged and both claimed a plane. So only one Japanese plane went down, but there were 2 claims.
However, there is definite over-estimation of hits and kill by Japanese fighters and carrier attackers--sometimes by a factor of 10. They will claim 8 hits on a carrier and only actually get 1 with a handful of near misses. They will claim ships sunk when they didn't even hit them or only did minor damage. They will fly out against a division of planes and claim fighter kills when they didn't even do noticeable damage.
With a few exceptions, there are no mentions of how these kills were reported. Only several times did Lundstrom note that the Japanese pilot radioed in a kill. Usually, he just summarizes what the claims were.
My question is as the title says. What is the cause of this? Was it the honor system in Japan? Was it the fear of failing their commanders? Were the over-estimations made by wing commanders or ship commanders also fearing the wrath of the Japanese High Command?
During World War II, different nations had different ways of tallying aerial kills. In the United States and Britain, the pilot was the one who accrued the kills. If two or more planes contributed to a kill, that kill was divided among them, creating fractional kills.
Germany, on the other hand, did not award fractional kills. If two pilots contributed shot down a plane together, they generally were awarded one kill each.
In Romania, there was a "bonus" system. Down a four-engine bomber, and you're awarded three kills. Down a two-engine aircraft, and you get two kills. A single-engine aircraft is worth one kill.
In Japan, Italy and the Soviet Union, kills tended to be awarded under a "collective" principle. The actual implementation of this varies by nation, but in general, the kill of an enemy aircraft is awarded to the group a pilot belongs to, not the individual pilot himself.
Adding to the difficulty of analyzing kills, each nation had different standards for confirmation. In the United States, the standard was very high. In Japan, it was extremely low. This meant there was no disincentive to prevent the natural inflation that takes place when a group is awarded a prize collectively.
My question is as the title says. What is the cause of this? Was it the honor system in Japan? Was it the fear of failing their commanders? Were the over-estimations made by wing commanders or ship commanders also fearing the wrath of the Japanese High Command?
I think this is where the question gets a little questionable as that goes too much towards speculation. As to the kill system in the IJN/IJA air force, as to my knowledge and rather poor memory, singular kills and group kills were counted separately leading to higher counts. But as to why the counts were inflated, the heat of battle and battle fatigue are reasons why many people up until after the Korean War (where dogfighting became less prevalent with heat seeking missiles and much more advanced optics and range finding) misreported or overreported kills. It's just simply far too difficult and chaotic to remember clearly whether or not the plane that was just shot down was truly finished.
As to the performance of Japanese pilots, attrition rates were rather severe, especially after 1943 where the tide of the Pacific Front started to turn against the Japanese. It also didn't help that the Japanese doctrine like the Germans and Russians revolved heavily around repeated missions for experienced aces and pilots. While this would mean that the pilots would rack up many kills (purported or confirmed), the pilots themselves were exposed to a much higher degree of risk.
Furthermore I'll have to add that this would be the crucial difference in disparity between German, Russian, and Japanese pilot kill counts. Part of it was indeed due to "over-reporting" but doctrines that the aforementioned three parties exposed pilots to the front lines far more than American Aces who were taken back to the rear lines to train and prepare new pilots. As the war dragged on, this doctrine would cause noticeable drops in the quality of pilots for the Japanese and Germans, notably after 1944. At any rate, It's less that pilots were purposefully over-reporting than the fact that accurately gauging the damage done is very difficult in the heat of battle. Couple it with battle fatigue, the higher amount of combat missions Japanese pilots would have due to being on the front lines constantly, and the variability of both ship and airplane damage that can be seen with the naked eye in battle and your answer lies within that area.
Sources:
I haven't read Lundstrom's book, but what you're describing here is apples and oranges. I.e. multiple US pilots claiming the same downed Japanese plane as a kill, vs Japanese pilots overestimating the number of bomb or torpedo hits they got on Allied ships.
AFAIK, US flyers were also prone to wildly overestimating the hits they got on enemy ships. Maybe because bomb splashes and smoke screens looked like successful hits?
So, I'd try to distinguish between air-to-air combat kills, vs hits on ships.