The inherent structure of human reason manifests itself in three acts of the mind: (1) understanding, (2) judging and (3) reasoning. These three acts of the mind are expressed in (1) terms, (2) propositions and (3) arguments. Terms are either clear or unclear. Propositions are either true or untrue. Arguments are either logically valid or invalid.
A term is clear if it is intelligible and unambiguous. A proposition is true if it corresponds to reality, if it says what is. An argument is valid if the conclusion follows necessarily from the premises. If all the terms in an argument are clear, and if all the premises are true, and if the argument is free from logical fallacy, then the conclusion must be true.
These are the essential rules of reason, in apologetics and in any other field of argument. They are not rules of a game that we invented and can change. They are rules of reality.
Not only reason but even language is more than a "game" (Wittgenstein's influential but misleading term); it has an inherent structure, for it is an expression of reason, which has an inherent structure. (In Greek, the same word, logos, means "objective intelligible structure", "reason as revealing that structure" and "word or speech as expressing reason".)
We write in terms, propositions and arguments because we think in concepts, judgments and reasoning; and we do this because the reality we think about includes essences, facts and causes. Terms express concepts which express essences. Propositions express judgments which express facts. And arguments express reasoning which expresses causes, real "becauses" and "whys".
Arguments are like eyes: they see reality. The arguments in this book demonstrate that the essential Christian doctrines are true, unless they are bad arguments; that is, ambiguous, false or fallacious. To disagree with the conclusion of any argument, it must be shown that either an ambiguous term or false premise or a logical fallacy exists in that argument. Otherwise, to say "I still disagree" is to say "You have proved your conclusion true, but I am so stubborn and foolish that I will not accept this truth. I insist on living in a false world, not the true one."