R is for the arguments that are not subject to rebutting.
Rebutting defeaters against theistic belief threaten the claim that theistic belief is (or can be) rational.
If someone presents a rebutting defeater against theism, one can respond by either rebutting or undercutting the alleged defeater.
Indeed, we can view this as an implication of any (rebutting or undercutting) defeater.
An approach to negotiation based on argumentation using rebutting and undercutting was presented, which could aid agents to specialise their particular roles or behaviours.
However, one could also rebut the original rebutting defeater.
The first kind of refutation is defined as a rebutting defeater.
Taylor offers both an undercutting and a rebutting defeater of the premiss that an actual infinite cannot exist.
