Originally Posted by Red Harvest
I don't think people realize how slow communications were at the time. Even had Japan declared war slightly in advance, it is unlikely that Pearl Harbor would have been able to react sufficiently. Even the radar that picked up the attack wave was a problem, because it did not yet have any direct communication link with the base (as I understand.) So even had the officer in charge recognized the threat, he might have been unable to do anything about it.
To appreciate just how bad US preparedness was, the Japanese attacked the Philippines the day after Pearl Harbor and caught many of the aircraft on the ground in nice orderly arrangement. The Japanese were shocked at the ease of the attack since they expected serious resistance from an alerted enemy.
I don't think naval policy would have been different if the carriers had been caught. There still would have been no doubt that carriers were needed, not battleships. It would have slowed the U.S. response down and it would have left Japan on the offensive longer since Midway would not have happened. Even had the carriers been hit, they would most likely have been refloated (at least some.)