{ 1 } - Both are based on pure thinking and not on sense experience.
{ 2 } - Both are named after the same Greek word.
{ 3 } - Both were required subjects for graduation.
{ 4 } - Both are based on observation.

We can examine animals and their behavior, and see why they do things. Similarly, we can examine humans and their behavior, and see why we do things. Ethics does the latter, according to Aristotle.

Critics object that observing our behavior can reveal what goals we have, but not what goals we ought to have -- and ethics is about the latter. Many human goals are bad.