The starting points all differ, some begin in empirical experience, some with an innate knowledge of the principles - of Scripture, etc. No one test for truth is adequate. Truth must be factual, rational, and relevant to moral or religious issues. Everyone must pick a starting point or premise. Neither are they philosophically neutral, since once you pick the premise, the conclusion is inevitable.
Formal logic is empty.
Experience is not self-interpreting. Truth is modeled after a scientific hypothesis. Positive Contributions Facts do not speak for themselves, they require meaning, which is superimposed on them from the outside before truth can be known. Combinationalism is comprehensive, and recognizes that a world-view must cover ail that is in the world. It is adequate within certain contexts.