In " The Cask of Amontillado" how does Fortunato's love of wine contribute to his down fall?
Fortunato's love of wine contributes to his downfall in a couple different ways: first, he takes such pride in his knowledge of wine that he jumps at the chance to gloat over what he believes is Montresor's mistaken purchase (Fortunato does not believe Montresor could have bought a whole pipe of amontillado at this time of year but that he has likely overpaid for something else). Montresor says, "He had a weak point — this Fortunato [...]. He prided himself on his connoisseurship in wine." This makes him willing to go deep into Montresor's catacombs, endangering his health as a result of the niter on the walls.
Second, Fortunato drinks a lot of wine once he and Montresor descend underneath the earth. He was inebriated even before he met Montresor in the street, and he becomes more and more so as they travel together through the vaults. Montresor says that his eyes looked like "two filmy orbs that distilled the rheum of intoxication." This makes him slow and impairs his judgment so that he does not pick up on strange clues — why does Montresor have a trowel (a tool to lay bricks) in his pocket? why would Montresor have hidden the wine so far back in the catacombs? — and this impairment helps lead to his own death.
Fortunato of "The Cask of Amontillado" has two flaws: he loves wine and he considers himself a great connossieur. In fact, it is his excessive pride which leads to his nemesis much more than his love of wine. However, his excessive drinking certainly inhibits his reasoning. For instance, when Montresor cautions him about the niter and the dangers of his becoming ill, Fortunato does not think about the threatening conditions; instead, he lets his desire to be the one to say that he has first tasted the Amontillado overrule any judgment.
In his drunkenness, too, Fortunato notes that the vaults are extensive, but he thinks nothing of getting lost in them. And, when Montresor makes a pun upon the word mason, Fortunato does not comprehend. So, when Montresor leads him into the dark recess, Fortunato is so inebriated that he does not back away in caution. When he is fettered to the wall, he is bewildered: "He was too much astounded to resist."
His own pride on his knowledge of wine makes him fall into Montresor's trap.