[hannasanarion]

Sure he did. He didn't follow the modern Bacon/Popper empirical method with testable hypotheses, but he still performed experiments and drew conclusions based on what he saw.

All beside the point: his observations are not invalid, his conclusions are

[yesenadam]

He made observations, sure, but what are some actual experiments he did? (Or where to read about that?)

[mattkrause]

So women do have fewer teeth?!

[coldtea]

No, but not because Aristotle was against observation. Just because he either miscounted or trusted a wrong earlier observation. What he wrote is:

"”Males have more teeth than females in the case of men, sheep, goats, and swine; in the case of other animals _observations have not yet been made_”

Emphasis mine.