I don't understand the example of

improve -> mastery

because of the language we see that student mastered = saw improvements, emphasizing that if there were no improvements, we can assume they didnt master the logic because if they has mastered, they would see improvements.

How is it that the mastery is the necessary condition? Couldn't it be assumed that if you didnt master it its not necessarily true that you didnt improve? It doesnt say that mastery is the ONLY way to see improvements so it could be assumed that more things could lead to improvement, but IF you master, youre sure to see improvement.

This was the question that got me as well. I definitely think that this is a weak argument because we have to assume that Michaelangelo's paintings are even being cleaned. I thought it was no argument because I would think of an argument more as saying something along the lines of "none of the chemicals used to clean the artwork in the sistine chapel will affect the original dyes, therefore..."