If two parties can not agree to the following five principles of debate, then the debate is unlikely to reach a correct and reasonable conclusion. Even with these principles in place, a debate may be unsolvable, as evidenced by apparent paradoxes in the perfectly logical and rigorous framework of mathematics.
1 : Both parties must be open to convincing by rational argument
2 : Both parties must argue for both sides of the debate
3 : Sloppy logic will lead to 'reasonable' but useless or incorrect results
4 : All evidence must be considered with equal statistical weight and fact-checked
5 : No Faith except that which is common to both parties
If principle 1 is violated, then the debate becomes a pointless exercise in contradiction.
If principle 2 is violated, then the debate may be decided based on who has more charisma or better rhetoric, not on which side is more correct. Adhering to principle 2 also ensures that both parties have respect and understanding of the opposing viewpoint.
Principle 3 is impossible to attain absolutely ( except in math ), but both parties should be disciplined and adhere to as rigorous of reasoning as is possible.
If principle 4 is violated then your debate has no firm ground to stand on, and it will devolve into an exercise in manipulating the truth rather than finding it.
If principle 5 is violated, principle 1 is automatically violated simply by use of contradictory axioms : the union of your reasoning frameworks automatically contains a contradiction, and no sound resolution is possible.
Some debates or arguments are too poorly defined to meet these five criteria. Some debates may contain within them an inherent contradiction to these five criteria.