Solozzo made a fatal mistake in underestimating Michael. But Sol sealed his own fate by making a bigger mistake earlier: letting Sonny’s show of greed convince him that Sonny would make a deal even if he killed Vito:

The drugs proposition was between Vito and Sol. But, Vito had Tess, Clem, Sonny, Fredo and Tom present. Why? I believe it was because Vito knew how drugs profits would stimulate greed, and tempt even his own most loyal people (N.B: the novel says Sonny wanted the deal to get out from under his father’s thumb and get some action on his own; and Sol knew Tom wanted the deal). Vito wanted all of them to hear his “no” at the same time—and he wanted Sol to see all of them hearing his “no”—so that none of them would be tempted to try to circumvent Vito’s will, and to preclude Sol from approaching them individually.

Sure enough, Sonny betrayed his greed at the meeting, encouraging Sol to kill Vito. But, Sol should have realized that shooting Vito backed Sonny into a corner: With all those witnesses to Vito’s “no,” he could never forego vengeance and go along with the deal without looking to the others that he betrayed his father for money. Sonny instinctively (and correctly) knew that he had no choice but to forego drug profits and to kill Sol to avenge his father.

In II, Michael tells Pentangeli that his father taught him to “think as others around you think.” If Sol had followed that advice, he would have realized that killing Vito would be the one thing to assure that Sonny, despite his show of greed, would never go along with his deal.

Your thoughts?