[q] Common Ground
[a] Common Ground (CG) is the set of epistemologically necessary conditions for thought and discourse. Without CG words are emptied of meaning; what is meaningless, due to lack of CG, is absurd. To deny CG is to deny the possibility of public discourse.
[q] Why is CG necessary?
[a] CG is necessary to avoid foolish arguments (what cannot be resolved because no basis for resolution is in place). A foolish argument only causes strife.
[q] Is avoiding foolish arguments optional?
[a] Avoiding foolish arguments is not optional; it is an imperative. Not avoiding foolish arguments would be epistemologically foolish, mistaken, a blunder, inept and unwise. What is foolish falls into the category of moral evil (denying human nature as rational), and its inherent consequence.