Scholar Fernando Segovia lists seven different scholarly approaches to John 14-17:
(1) Historicizing: the discourse is completely accurate, therefore chapter 15 occurs in a different location (because of 14:31).
(2) Transpositional: sometime during transmission, the chapters were rearranged.
(3) Redactional: there is a second speech (chapters 15–16) which is a different version of the first speech (chapter 14).
(4) Symbolic: 14:31 is understood symbolically.
(5) Unfinished: the text is a “rough draft;” the author did not finish polishing the text.
(6) Compositional: the apparent contradictions in the text were deliberately crafted by the author to provoke the reader to think.
(7) Integrative: regardless of the text’s history, we should ask: How does it now read? One example of this is to find a chiasmus:
A love, glory (13:1–38)
B Jesus’ departure (14:1–31)
C joy/hate, abiding/persecution (15:1–11)
D focal point: 15:12–17
C’ joy/hate, abiding/persecution (15:18–16:3)
B’ Jesus’ departure (16:4–33)
A’ love, glory (17:1–26)
For which of the above theories can you make a good case based on the evidence in the text? Which ones seem without merit?
(adapted from Search, Ponder, and Pray: A Guide to the Gospels)
If all you have is a hammer, every problem looks like a nail. Similarly, if you take just one approach to scripture interpretation, you’re only going to encounter the solutions that that methodology can offer. In the case of John 14-17, commonly known as the Farewell Discourse, different approaches will offer you different possible solutions to the problems of the text–the main problem being that the conclusion to chapter 14 implies that Jesus is about to begin a journey, but chapter 15 is a continuation of his teachings with no indication of any change in location.
Basically, any time we find unevenness in the text, we can chalk it up to a sloppy author, a complicated textual history, or transmission problems (not the car kind–the kind where a scribe messes up). Or we can approach the text from a literary perspective and ask: why might the author have deliberately put this wrinkle into the text? What might I learn from it? Or even if the author didn’t do it deliberately, if I take the text as a whole, how might I best interpret it as it now stands?
I’m a proponent of literary approaches (which isn’t to say the other ones aren’t useful). Sometimes, we’ve been too quick to reach for the “ah, the text is just messed up” explanation when a more satisfactory literary explanation was waiting patiently for us to notice it (here’s an example).