If the US carriers had been at Pearl Harbor

What if the US carriers had been present at Pearl Harbor?

They would likely be heavily attacked or sunk, removing the basis for early carrier raids and sharply worsening the opening balance in the Pacific.

The answer treats the carrier presence as a major worsening of the attack rather than a minor variation. Japanese aircraft would prioritize the carriers, and their loss would remove the platforms used for the early American carrier raids and the Doolittle Raid. The Pacific war would therefore begin with a much weaker American ability to strike back or contest distant waters. The speakers also argue that the shock would make Britain's earlier pause in carrier capital-ship construction look still more costly. Their leadership lesson is that decisions based on the expectation of repeating the last war can fail when the next conflict has a different geographic and operational shape.