Why Lexington-class carriers carried 8-inch guns

Why discuss Enterprise before Saratoga and her 8-inch guns?

The guns were difficult to justify under the original Washington Treaty, but gained limited logic once later treaty rules capped cruiser numbers.

Under the Washington Naval Treaty, there was no total cap on cruiser numbers. A navy could therefore build a separate 8-inch cruiser instead of burdening an aircraft carrier with heavy guns, saving weight for aviation. The London Naval Treaty later imposed cumulative cruiser limits and gave the carrier guns a temporary logic because they supplied cruiser-like firepower outside the capped cruiser force. That logic faded as carrier warfare matured. By then, any enemy cruiser reaching gun range of a carrier indicated that the carrier screen and the wider operation had already gone badly wrong.