A question about DN 23 and existence of soul Here is a part of DN 23:

“Even though Master Kassapa says this, still I think that there’s no afterlife.”
“Can you prove it?”
“I can.”
“How, exactly, chieftain?”
“Suppose they were to arrest a bandit, a criminal and present him to me, saying, ‘Sir, this is a bandit, a criminal. Punish him as you will.’ I say to them, ‘Well then, sirs, place this man in a pot while he’s still alive. Close up the mouth, bind it up with damp leather, and seal it with a thick coat of damp clay. Then lift it up on a stove and light the fire.’ They agree, and do what I ask. When we know that that man has passed away, we lift down the pot and break it open, uncover the mouth, and slowly peek inside, thinking, ‘Hopefully we’ll see his soul escaping.’ But we don’t see his soul escaping. This is how I prove that there’s no afterlife.”

(Payasi argues there is no soul so no afterlife.)
However, Kassapa, one of the principal disciples of Gautama Buddha, argues there is a soul. He further says in DN 23:

“Well then, chieftain, I’ll ask you about this in return, and you can answer as you like. Do you recall ever having a midday nap and seeing delightful parks, woods, meadows, and lotus ponds in a dream?”
“I do, sir.”
“At that time were you guarded by hunchbacks, dwarves, midgets, and younglings?”
“I was.”
“But did they see your soul entering or leaving?”
“No, they did not.”
“So if they couldn’t even see your soul entering or leaving while you were still alive, how could you see the soul of a dead man? By this method, too, it ought to be proven that there is an afterlife, there are beings reborn spontaneously, and there is a fruit or result of good and bad deeds.”

In the above Sutta DN 23, Kassapa proves that there is a soul. Kassapa, who directly got knowledge from Buddha argues there is a soul and that is what travels to the afterlife. But we who have never seen or been taught by Buddha say there is no soul. We are furthermore down in a timeline than Kassapa. Knowledge might have changed and we must have interpreted something very simple in a complicated way. Why do we say there is no soul, while the direct disciple of Buddha says there is in fact a soul that goes to the afterlife. Remember that Kassapa was the third most liked disciple of Buddha after Sariputta and Ananda. I think today we have completely changed our point of view. There is also not any sutta where Buddha says no soul. But he says, this is not-self. The things in the physical world are not-self. Like feeling is not self, perception is not-self and all things that are created in the body are not-self.
What's your point of view on the soul? How can you argue with Kassapa who has seen and learned Suttas direct from Buddha?
You wrote ...


  (Payasi argues there is no soul so no afterlife.)
  
  However, Kassapa, one of the principal disciples of Gautama Buddha, argues there is a soul.


... but I don't think so. Instead I think the dialog or argument in the sutta is:


Payasi: there is no afterlife because we don't see a visible soul leaving the body at death
Kassapa: the existence of a visible soul is not necessary for there to be an afterlife (for example when you dream there's no visible soul living the body) -- the non-existence of a visible/separating soul doesn't prove there is no afterlife


That (saying "the existence of a soul isn't necessary, and needn't be assumed") is not the same thing as saying "there is a soul".
The main argument is about "afterlife", it is not about "soul".

Secondly the argument in Pali uses various words like:


  
  āyu
  life; vital power; duration of life, life-time; long life.
  jīva
  


Those words are used in several suttas -- in MN 63 for example, where various questions about the body and soul are declared to by the Buddha to be "not declared":


  And why haven’t I declared these things? Because they aren’t beneficial or relevant to the fundamentals of the spiritual life. They don’t lead to disillusionment, dispassion, cessation, peace, insight, awakening, and extinguishment.


Thirdly, even if Buddhist doctrine did say that something like that existed, and if someone translated that statement or that word as "soul", I'd try to doubt whether the word "soul" there has the same kinds of meanings as is taught by other religions