Body and mind
Q: Please explain why you don't believe in the existence of a self.
A: Tell me what you are.
Q: I am my personality, my mind, my thoughts.
A: Is your body not you?
Q: My body is me as well.
A: Then the combination of your body and thoughts are "you".
Q: Yes.
A: In that case I have a very serious question for you: what is this conglomeration of "body and thoughts"? Where does it begin and end? Is your body not dependent on the outside world for food? Is your mind not similarly dependent on the outside world for experience? Then how can you separate your mind and body from the outside world?
Furthermore, your body and mind are continually changing, so which "body and thoughts" are you?
Q: I can see how all things are in a state of continual flux, but how do you reach the conclusion that things lack self-existence?
A: Nothing is the same for two consecutive moments. Before we can posit the existence of a thing, that thing becomes something different. You are a different person to the one that existed five minutes ago.
Q: Yes, I change, but a part of me remains the same.
A: Which part exactly? Are you saying some things are immune to change?
Q: Don't you even believe in the existence of a soul within the body?
A: "Soul" is but an appearance, and a useful abstraction. It is a word for something which appears to have continuity and to be the master of the body. The soul is no different to "Wednesday" or "wind" in being a mere adventitious designation.