From The Secret War: Spies, Cyphers, and Guerrillas, 1939-1945, by Max Hastings:
“The first requirement for successful use of secret data is that commanders should be willing to analyze it honestly. Herbert Meyers, a veteran of Washington’s National Intelligence Council, defined his business as the presentation of ‘organized information’; He argued that ideally intelligence departments should provide a service for commanders resembling that of ship and aircraft navigation systems. Donald McLachlan, a British naval practitioner, observed: ‘Intelligence has much in common with scholarship, and the standards which one demanded in scholarship are those which should be applied to intelligence.’ “
Hastings goes on to reference German commanders after the war blaming their intelligence failures on Hitler’s “refusal to countenance objective assessment of evidence” – especially if the reports were unfavorable [to his views].’
Useful lessons here even outside the military and national security domains, but seems especially timely these days. Bad enough to try to fool others. Fooling yourself is especially dangerous.