The human brain is the most complex thing we will ever encounter.
I have learned over many years of deep thoughtful debate with various people that before two parties can settle an argument or come to agreement on an issue they must first agree to a set of rules for "the game." Any game (except maybe war) has to have agreed upon rules for the play and the determination of a "winner." In this case, for determining the truth. Think of playing a football game without clear rules and unbiased referees to see that they are followed. It is futile.
The problem with philosophical arguments is that they always end up being arguments about the rules. Once we realize that we can't agree on the rules of determining the truth the only option short of war (physical force,) is to give up. We must abandon the "game." To continue would ultimately result in a battle of brute force or war.
A philosophical competition is played with our minds to determine the truth, so the rules we must agree on end up being the crux of the argument. In football, for example, the teams agree to accept only certain factors as being relevant to the game's outcome. They agree that the goal posts and boundary lines actually exist and that referees will decide if the lines or uprights have been crossed. The game cannot be played civilly otherwise. The "game" of life is much more important.
In order to live together peacefully on earth we need to agree on objective rules for social debate. That is the realm of philosophy. If the philosophy of the majority is one that allows conjectures, faith, and faulty logic, then the only means of settling arguments is through physical force. If the philosophy of the majority recognizes only solid rules of logic, evidence of the senses and verifiable facts based in reality, then truth can be determined through civil reasoning. This is not saying that we can know everything, but that we agree to exclude things we don't know from the arguments.
