I am going to take a starting stab at listing some questions that RT principles may open up to us in the exegesis of just Thomas' words in John 20:28. I want to do some work on that passage in the light of this anyway at some point. This list could be opened up a lot through examining the wider context and a wider range of RT concepts
Do we know the mutually manifest information to Jesus and Thomas?
What is the cognitive environment in which these words are uttered?
Representation / Metarepresentation
Are Thomas' words ο κuριος μου και ο θεος μοu a direct representation or an interpretive metarepresentation
If a metarepresentation - is this of someone else's thoughts / speech, or of his own thoughts
Is John's reporting of Thomas' words a direct or interpretive metarepresentation
If direct, is this due to the original language of Thomas' words being in Greek?
Is it possible to have direct representation when translating from one language to another if the original was in Aramaic / Hebrew?
If interpretive, in what way is it interpretive?
Lexical broadening / narrowing
matched to the context of John's Greek audience?
Matched to the LXX?
in what way are the terms κυριος and θεος modulated in the context?
κυριος intended to be in a broad sense of a teacher / disciple relationship?
Is this metaphorical
κυριος intended to be specific
κυριος modified by θεος to indicate not just Lord but divine Lord?
Expectation of optimal relevance
Are Thomas' words an act of ostensive communication to Jesus or a mere expression of his own thoughts to himself?
How may Thomas' words be optimally relevant to Jesus
New belief formed from inference in the context?
Letting Jesus know that he accepted him as risen from the dead
Letting Jesus know that he submits to His authority
Letting Jesus know that he views him as God?
Cancellation of a belief
Thomas disbelieves in the resurrection
Thomas no longer accepts Jesus' Lordship due to his crucifiction?
Reinforcement of an belief
What are the encyclopaedic connotations of Lord and God?
Does the LXX shema have an influence here with the conjunction of Lord and God?
Does the two power's in heaven theology have an impact here?
application of "lord" to Caesar?
Is there procedural meaning in the text?
How does και constrain the processing of the narrative
additive of two separate expressions? "my Lord" "my God"?
What pragmatic enrichment needs to take place in the text?
"I recognise you now to be by Lord and my God"?
"I recognise you at last to be my Lord and my God"?
What are the implicatures that can be drawn from the text?
I now believe that you are risen
I submit myself to your authority