I mean that there are always some elements of text that are not written for sake of the general audience. If you had no experience reading on a topic of law (say for example), and then attempted to read the 4th year law students textbook, you'd get lost a bit; because, it wasn't written for a novice. There is a lot of information left out that is taken for granted that you ought to know. Even the most intelligent person in the world would struggle through text that they have little or no prior experience of. It's not your fault. So, for the time being at least, you must ignore parts of it, and muddle through.I don't know what inferential nonsense means.
I don't skip ahead in books, but I'll skip really long posts here.