How We Determine If It Is A Good Question

A big principle from Rav Gustman ztz"l: Many times the rishonim answer a question with the words ולא קשה מידי or לא קשה כלל and other times they answer with the words ויש לומר or ויש ליישב. Why do they use different terms?

The underlying premises that led to a question may ALSO be a correct understanding and approach to the sugya [even though the question is answered]. In such instances the rishonim will say ויש לומר or ויש ליישב. However, in other instances there is a fundamental misunderstanding that led to the question. In such a case, the rishonim will say ולא קשה מידי or ולא קשה כלל.

ספר הליכות ישראל בהקדמה