συμμαρτυρούσης αὐτῶν τῆς συνειδήσεως … κατηγορούντων ἢ καὶ ἀπολογουμένων

Says 2:15b adds two genitive absolutes, each built on a present participle: 1. συμμαρτυρούσης αὐτῶν τῆς συνειδήσεως, "their conscience bearing witness with them"; 2. καὶ μεταξὺ ἀλλήλων τῶν λογισμῶν κατηγορούντων ἢ καὶ ἀπολογουμένων, "and their thoughts between one another accusing or even defending."

The BSB has "their consciences also bearing witness, and their thoughts either accusing or defending them."

Abbott-Smith defines συνείδησις (syneidēsis) in its ethical sense as "innate discernment, self-judging consciousness, conscience," citing Rom 2:15, and λογισμός as "a reasoning, thought."

Implies The συν- of συμμαρτυρέω most naturally adds a second witness: the conscience confirms what their conduct already shows (2:14–15a). Paul uses the same construction in Rom 9:1, συμμαρτυρούσης μοι τῆς συνειδήσεώς μου.

Implies ἢ καί, "or even," marks defending as the less expected outcome; the thoughts mostly accuse. The courtroom verbs (κατηγορέω, ἀπολογέομαι) look ahead to the day of 2:16 and recall ἀναπολόγητος in 2:1.

Uncertain Whether μεταξὺ ἀλλήλων means (a) each person's thoughts debating within, or (b) people's thoughts toward one another, accusing or defending others. This note leans to (a), which suits the parallel with the inner witness of conscience; (b) is grammatically possible and is the main alternative.