TB, I agree. However, I've never maligned Sonny's intelligence though. On the other hand, I recognize Sonny's emotions as his personal pariah. Remember the scene when Tom tells Sonny that if they go after McCloskey all hell would break loose. Just a minute before Sonny was hell bent to murder Sollozzo and McCloskey. However, Tom appeals to Sonny's sense of logic and Sonny concedes to Tom.

How many times do any of us make decisions based on emotion instead of intelligence? Sonny just seemed to have more emotion than many of us, so that emotion impaired his intelligent action.