Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person Omniscient
Oh, hey, third person omniscient.
Joseph gets a lot of playing time in the story, but the real star of the show is the intrusive narrator. That pesky guy weaves in and out of every character's consciousness; he knows everything about everything, and he'll tell you what's up even when the characters are lying through their teeth.
Check out how this tidbit, for example, when the narrator gives us the real scoop about what Lady Booby'll do to get at Joseph: "She resolved to preserve all the dignity of the woman of fashion to her servant, and to indulge herself in this last view of Joseph […]" (1.7.6). Yeah, that narrator's a sneaky son of a gun.
The best parts, though, are when the narrator decides to give us a little sermon of his own. What, he doesn't think it's enough to make us listen to Parson Adams? No sir: our bud the narrator is particularly fond of holding forth at the beginning of each volume in Joseph Andrews. Sometimes, he even gives us insights into the author's trades: "I take this dividing of our works into books and chapters to be none of the least considerable [secrets]" (2.1.1). What does that have to do with Joseph? Nothing, but our third person omniscient narrator is going to tell us, anyway.
Actually, all this chatter about constructing a novel does have some purpose. Fielding wrote Joseph Andrews as send-up of Samuel Richardson's Pamela, so when he talks about how to properly construct a novel, you can bet he's giving the middle finger to old Richardson and saying, "Hey, buddy, here's how you write a real novel."