There are many ways to violate the principal of rational discussion.Begging the question is a fallacy in which the conclusion is presumed to be true without any evidence other than the claim. The claim is thought of to be already valid, but no reason why the claim is true. The Epstein edition states that begging the question is “The point of an argument is to convince that a claim is true. So the premises of an argument have to be more plausible than the conclusion”.
Example:
Past-life memories of children prove that past lives exist because the children could have no other source for their memories besides having lived in the past.
This example is a fallacy because it is presumed that past lives do happen because children have past-life memories. There is no evidence proving the claim that children have had past life memories. The whole argument is invalid.