why did starbuck protest ahabs intention to kill moby dick

Starbuck is a more practical man than Ahab, and knows it is a fool's game to continue chasing the whale. He knows it endangers the ship and the lives of the men on it to let Ahab pursue the whale with such vehemence. It is his job as first mate to keep the ship safe, and so he opposes Ahab's plan.

Starbuck thinks that Ahab's vendetta is pure folly. The whale is merely a , "brute...that simply smote (Ahab) from blindest instinct." The whale is an animal acting out of instinct. It holds no malice or anger to Ahab or anybody. Starbuck feels that Ahab's thrust for vengeance against the animal is "blasphemous" against the natural order of things. Starbuck also doesn't want to get caught up into Ahab's world which Ahab himself described as "demoniac...madness maddened".