Then there arose a reasoning among them, which of them should be greatest. There arose a reasoning - Εισηλθε δε διαλογισμος, A dialogue took place - one inquired, and another answered, and so on. See this subject explained on Matthew 18:1 (note), etc.
Related Commentaries of Luke 9:46
Luke 9:46
46 Then there arose a reasoning among them, which of them should be greatest.