One of the catchword arguments that P.N. Harrison uses in his book The Problem of the Pastoral Epistles (Amazon.com) has to do with how Paul usually expresses thanks. Here's Harrison:
In expressing his thankfulness to God, Paul consistently uses the word ευχαριστεω (Ro 1.8; 1Co 1.4; 2Co 1.11; Eph 1.16; 5.20; Php 1.3; Col 1.3; 1Th 1.2; 2Th 1.3; 2.13; Phm 4); this author never writes that word, but uses instead the Latinism χαριν εχω (= gratiam habeo) 1Ti 1.12; 2Ti 1.3. (Harrison, 28-29)
I've always been intrigued by this. First, because Harrison assumes his conclusion in the first sentence where he mentions what "Paul consistently uses"; second because he's right about the discrepancy (not Pauline authorship). The Pastorals don't use ευχαριστεω in thanksgiving sections, other Paulines do.
Why bring this up? This morning I began digging back into my translation of Second Timothy, and I ran into 2Ti 1.3, where χαριν εχω is used. And I have a few thoughts on this now.
Some of Harrison's cited instances (Eph 1.16; 5.20) use ευχαριστεω as a participle in a series of modifications, not as the primary verb. His 2Co 1.11 instance may implicitly refer to God as receiving the thanks, but is doesn't explicitly state it. And note that 2Th 1.3; 2.13 use ευχαριστεω as an infinitive, modifying the verb οφειλομεν. Again, not an exact syntactic parallel for the phenomenon under discussion. Note also that Harrison missed 1Co 14.18, which should be added to his list.
Of course, I'd suppose that Harrison (and others) would see these as evidence that Ephesians and Second Thessalonians aren't Pauline either. In any case, the are not direct examples of the phenomenon he is trumpeting, so they shouldn't be listed as evidence for or against his lexical/syntactic argument here.
In the non-Pastorals usage at the head of thanksgiving sections, ευχαριστεω always takes "God" as its complement: "I give thanks to God". More specifically, it is ευχαριστεω τω θεω. In 1Ti 1.12, it is not "God" that Paul thanks with χαριν εχω, it is "the one who has empowered me, Christ Jesus our Lord". Still in the dative, but not quite apples-to-apples.
But that still leaves 2Ti 1.3, which has χαριν εχω τω θεω (compare to ευχαριστεω τω θεω in Ro 1.8; 1Co 1.4; 14.18; Php 1.3; Col 1.3; 1Th 1.2; Phm 4). This is actually Harrison's stronger counterexample (though he doesn't mention it).
My thoughts? Well, εχω (present active indicative first-person) + dative is not unknown in Paul (Ro 12.4; 15.17; 1Co 2.16; 7.25; 8.1; 9.4, 5, 6, 17; 11.16; 12.21; 2Co 3.4; 4.7; Gal 6.10; Eph 1.7; 2.18; 3.12; Col 1.14; 2.1; 2Th 3.9), so it is a structure that Paul could've used. I haven't examined these instances so I don't know exactly what contexts they occur in, if they take references to the deity as complements, etc.
But one interesting item that comes up is Luke 12.50 (yes, Luke). I've always been enamored with the theory that Luke was Paul's amanuensis for the Pastorals, and that his role may have even been closer to co-author. Luke 12.50 is as follows:
NA27: βάπτισμα δὲ ἔχω βαπτισθῆναι καὶ πῶς συνέχομαι ἕως ὅτου τελεσθῇ
ESV: I have a baptism to be baptized with, and how great is my distress until it is accomplished!
This is mildly interesting to me because the same thing could be said a different way. In fact, it is said a different way in Mark 10.38:
NA27: ὁ δὲ Ἰησοῦς εἶπεν αὐτοῖς· οὐκ οἴδατε τί αἰτεῖσθε. δύνασθε πιεῖν τὸ ποτήριον ὃ ἐγὼ πίνω ἢ τὸ βάπτισμα ὃ ἐγὼ βαπτίζομαι βαπτισθῆναι;
ESV: Jesus said to them, “You do not know what you are asking. Are you able to drink the cup that I drink, or to be baptized with the baptism with which I am baptized?”
In other words, in Luke's rewrite of this idea (sure, I think Luke used Mark as source (cf. Lu 1.1-2), but I also think Q is a load of hooey) he uses "I have a baptism" instead of "I am baptized". He uses an εχω construction instead of the plain verb.
I realize it's a reach built on next to nothing, but hey, this is a blog post so why not? Could Luke have done the same thing with Paul's words? Paul says ευχαριστεω τω θεω; Luke writes χαριν εχω τω θεω. Same idea, same stuff being communicated, just a different way of doing it. As Witherington posits, it's the voice of Paul but the hand of Luke.
I've always seen the amanuensis argument (whether it is Luke or not) as a strong one in favor of Pauline authorship/responsibility because we know that Paul uses an amanuensis in other letters. Many of the "style" arguments that seem so valid in challenging Paul's authorship can probably be seen (I'd say better seen) as pointing to different amanuensis situations, not to mention different roles of the amanuensis, influence of listed (and perhaps unlisted) co-authors, genre and the target of the letter.
Anyway, this is too long and I've gotta go. Perhaps more on this later (but perhaps not).