Yes it is hard to tell what’s an error.
Knowing what’s an error sounds important to learn philosophy. It also seems important to be able to tell what’s an error or not.
In arithmetic, you can add 2 plus 2 and be able to tell that it’s 4. If you work on a bigger problem that involves adding 2 plus 2 then you’ll be able to tell you got that part right.
What does clear cut mean? I saw that merriam webster said it’s something that’s free from ambiguity or uncertainty. So I think it’s stuff you don’t have to double check so much.
I think the quoted sentence above is related to the other quoted sentence, talking about why it’s hard to tell what’s an error in philosophy.
Learning the names of a country on a globe sounds more clear cut cuz if you have good memory skills then you can get less errors.