a conjunction that sets a frame of reference: "just as, even as, inasmuch as, when"
καθώς is the everyday Greek connecting word that tells the reader how to take one clause in light of another. It points back to a standard, a reason, a degree, or a moment that governs the main clause. Where English usually reaches for "just as," the Greek word does more: it can
- say to what measure something is done
- give the prior fact that makes a claim hold
- mark the moment when something began
The word was built from two smaller words meaning roughly "down from how," and in ordinary speech it pushed aside the older, more literary words for "just as" (καθάπερ, ὥσπερ). By the time of the New Testament it was the plain, everyday word, common in letters, contracts, and the street. The strictest stylists of the day looked down on it, which only confirms how common and how informal it was.
The Greek Old Testament stretched its range further by using it as the standard translation for a Hebrew word (אשׁר) that itself means "just as," "when," and sometimes "because." New Testament writers, steeped in that translation, picked up its wider range. This is why the word in Paul and John does things it rarely does elsewhere: it binds a prior act of God to a human duty that follows from it, and in Jesus' farewell teaching in John it roots the disciples' love and mission in the life shared between the Father and the Son.
Nuances
Disputed
Whether the causal/grounding sense ("inasmuch as, because") is a genuine lexical meaning of καθώς or merely a contextual inference from its comparative core.
- majorityThe causal/grounding sense is a genuine and distinct functional meaning, attested in BDAG (senses 3), Thayer, Friberg, and warranted at Romans 1:28, John 17:2, 1 Corinthians 5:7, Ephesians 1:4, and Philippians 1:7.; BDAG, 3rd ed., s.v. καθώς 3; Thayer, Greek-English Lexicon, s.v. καθώς; Friberg, Analytical Lexicon of the Greek New Testament, s.v. καθώς
- minorityApparent causal force is always strong correspondence or correlative comparison; the comparative meaning never wholly sheds itself and "cause" is contextual inference, not a separate lexical entry.; C. E. B. Cranfield, Romans, ICC, 1975, on Romans 1:28; Douglas Moo, Romans, NICNT, 1996, on Romans 1:28; Andrew Lincoln, Ephesians, WBC 42, 1990, on Ephesians 1:4
Whether the Johannine καθώς...καί and καθώς...κἀγώ correlatives express (a) pure comparison, (b) pattern plus grounding, or (c) participatory union with the Father-Son relationship.
- majorityThese correlatives express pattern plus grounding: Christ's love and mission are both the standard and the enabling power of the disciples' analogous reality, drawing believers into the Father-Son dynamic.; Rudolf Schnackenburg, The Gospel According to St. John, HTC; Raymond Brown, The Gospel According to John, AB 29A; D. A. Carson, The Gospel According to John, Pillar; Marianne Meye Thompson, John: A Commentary, NTL, 2015
- minorityThe καθώς-correlatives express comparative correspondence only; the unity of believers is modeled on but not identical with the Father-Son union, and ontological inflation should be resisted.; C. K. Barrett, The Gospel According to St. John, 2nd ed., 1978, on John 17:21-23; Andreas Köstenberger, The Missions of Jesus and the Disciples, Eerdmans, 1998