This passage has been the subject of no small controversy in recent centuries. I don’t intend to solve it all with a brief blog post. But I would like to make a few comments on the use of καί and its implications for the possible interpretations. A friend asked me a question about it, so I figured I’d take the opportunity to put some theology on a blog that is supposed to be about theology!
There are three functions of καί that are possible candidates for this text. They follow in order of grammatical likelihood (i.e., not giving considering to contextual or theological factors).
The most basic meaning of καί is and—a coordinating conjunction that joins two or more distinct items. While this is the most likely meaning from a grammatical perspective, contextually, this is absolutely impossible. Paul pronounces peace and mercy on those who walk in accordance with his rule (κανών)—that Gentiles are equal to and on the same plain as Jews and that the former need not submit to circumcision, et al. in order to be right with God and be part of God’s covenant people. Verse 15 is a summary statement for the argument of the book. Ιt is absolutely inconceivable that Paul would be pronouncing a blessing on two distinct groups of people: those who obey his instructions and the Jews (who don’t obey them—the necessary implication if καί means and). Oddly enough, Paul Benware defends the meaning of and here in a very befuddled argument (see Understanding End Times Prophecy, 87-89). O. Palmer Robertson obliterates this view in his The Israel of God, 40ff.
The next most likely possibility for καί is the meaning even. In this sense, καί functions to introduce an appositive and is semantically equivalent to “that is.” Paul would be pronouncing a blessing on all those who obey his instruction, that is, the (true) Israel of God. This position has the most arguments in its favor. (1) It’s the more probable of the two viable functions of καί. (2) Paul’s argument and specific references in Galatians fit perfectly with this conclusion. (3) Paul’s theology elsewhere supports this. And (4) the broader theology of the NT makes this the most natural and probably meaning.
There is a third possibility here, which, unfortunately, O. Palmer Robertson doesn’t acknowledge or interact with. The function of καί could be especially. This is rare, but there are some examples where this seems to be the only possible function of καί. I came across one several months ago during my daily reading in the Greek New Testament (which has been put on hold until I finish my dissertation). In Mat 8:33, we read this: “The herdsmen fled, and going into the city they told everything, especially [καὶ] what had happened to the demon-possessed men.” The second component is clearly a subset of the first. Interestingly, this is the only place in the NT where the ESV translates καί as especially. (I found that out by using the data from Logos’s new ESV Greek-English Reverse Interlinear New Testament.) BDAG lists two NT passages and two LXX passages that support this meaning (see 1aγ). So I believe that it’s possible from a grammatical standpoint that Paul is addressing two groups: the first being all those who follow his rule and the second being a subset of the first group, namely, the ethnic Jews within that group who follow his rule. However, when the argument of the letter and the broader theology of Paul and the NT are brought into consideration, this view becomes improbable at best.
Note: There are a couple factors that I was unaware of and thus overlooked with reference to view #1. See my follow-up post for my improved (hopefully!) analysis.