This statement sounds very uplifting, but is it true? Do all people really desire to know?
At first glance it is easy to refute Aristotle by pointing to individuals who are in this respect either indifferent or cognitively defective. But these counter-examples are ineffective against a normative proposition which states what humans can and ought to do. Had Aristotle said that "all men desire to know" his thesis would have been only a factual statement contingent upon an actual state of affairs. But he has inserted the phrase "by nature" which indicates what humans do if they are up to their real potentials.