How did Aristotle influence Alexander?

He was his tutor, and consequently helped shape his mind and thinking.

Commentary:

Aristotle's focus on investigating and observing would have undoubtedly been valuable skills for a military commander. The ability to size up a situation and find a truth based on those observations is the essence of almost every strategic battle move. Aristotle also emphasized classification and organization, which would be important for moving an army and performing tasks efficiently. This type of organization carried over to Alexander's governance of the empire. Classification and organization break things down into smaller parts, and Alexander would have seen the strength in numbers, and how large similar groups retained power over smaller more diverse groups. By creating a common culture and bringing Greeks to blend in with other peoples, he in effect created a wider, broader class. Although investigation and observation are a good way to organize and oversee a situation, Alexander would also have been taught to realize that the best way to maintain that is to find ways to keep the people involved happy. In Ethics, Aristotle addressed this very problem, and understanding this question is surely a large reason why Alexander was able to successfully run an army and unify an empire.