Here is the actual section from Runge:
Runge wrote:Heckert describes ἀλλά as a “global marker of contrast,” one that “introduces a correction of the expectation created by the first conjunct; an incorrect expectation is cancelled and a proper expectation is put in its place.” If we take the traditional idea of “adversative,” this particle does more than just indicate contrast. This holds true even if the preceding element is positive rather than negative. It provides a corrective to whatever it stands in contrast with. Levinsohn adds, “When ἀλλά links a negative characteristic or proposition with a following positive one, the negative proposition usually retains its relevance.”
Although there are several contrastive or adversative particles, ἀλλά adds the unique constraint of correcting some aspect of what precedes. In terms of distinguishing ἀλλά from εἰ μή, the key is the relation of what follows the particle to what precedes. In the case of εἰ μή, the excepted element that replaces what precedes was a potential member of the negated set. In the case of ἀλλά, the correcting member was not a member of the original set; it is a new element.
Runge, S. E. (2010). Discourse Grammar of the Greek New Testament: A Practical Introduction for Teaching and Exegesis (p. 93). Bellingham, WA: Lexham Press.
It's somewhat complicated in James 2:18 because the writer is introducing a hypothetical interlocutor posing an objection. But to what is he objecting? To the literal previous argument or something else that James has in mind? I"m a bit pressed for time, so I found a commentary which neatly summarizes what I might have written:
CBC wrote:2:18 Dibelius (1975:154) says “the problematic v. 18” is “one of the most difficult New Testament passages in general.” Everyone agrees that the verse introduces a hypothetical interlocutor, but there is wide disagreement as to how he functions in the argument and how to separate what he says from what James says. The major options are: (1) He is an ally of James, and his statement encompasses all of 2:18. He argues against the “faith” person that without works that person cannot prove there is any faith (NASB, Adamson, Mayor, Mussner). (2) He is an opponent or critic of James, and James responds to him in 2:18b (NLT, TNIV, ESV, Blomberg and Kamell, Davids, Dibelius, Johnson, Laws, Moo, Ropes, McCartney). See following notes.
Now someone may argue. In the ancient world this formula (lit., “But someone will say”) always introduces an opponent to the thesis (see especially McKnight 1990). This supports the second view, that the interlocutor is a critic of James. Nearly all recent interpreters have been convinced by this evidence.
Osborne, G. R. (2011). James. In P. W. Comfort (Ed.), Cornerstone Biblical Commentary: James, 1–2 Peter, Jude, Revelation (p. 60). Carol Stream, IL: Tyndale House Publishers.
N.E. Barry Hofstetter
Instructor of Latin
Jack M. Barrack Hebrew Academy
καὶ σὺ τὸ σὸν ποιήσεις κἀγὼ τὸ ἐμόν. ἆρον τὸ σὸν καὶ ὕπαγε.