Have you ever thought about how we know what we know, and if we claim to know it–is it really true? Can I believe that this is true?  Will I stand firm on what I know to be true? If two plus two equals four then is the truth that I believe as equal in its non-deniability as is the equation of two plus two equals four?  We all have to believe in “truth” or as things as being true. Truth itself is core part of our being and we expect and depend upon that everyone else holds to this same core belief–truth is true.  If we do not, then what can we depend upon? How can I trust, or why would I trust anyone or anything?  If I cannot trust in truth–then what? This is deeply troubling–I would want to know thetruth–wouldn’t you.
Here is an excellent part of a well written and informative article that you should ponder and come to reason with.
How do we know what we know?
Epistemology is the department of philosophy that deal with the science of knowing.  It comes from two Greek words for science (episteme) and knowledge (logos).  The way in which you answer the question of epistemology will determine the trajectory and therefore the results of your entire philosophical deliberations.  Do we fundamentally know things as a result of reason and experience or by faith and revelation?
All “knowing” requires faith.
All philosophies begin with a set of assumptions that can’t be proven. The non-believer as well as the believer starts with a commitment to some ultimate authority.  For the Christian it should be the Word of God, for the unbeliever it’s ultimately his own mind.  Either you are a law unto yourselves (auto-nomy) or you are under God’s revealed will (theo-nomy).
Non-Christians believe man can find truth by various means. He can make scientific observations and come to rational conclusions or resort to intuition and self-enlightenment.  But, according to the Bible, the mind and heart of man are limited because he is a creature, fallible because of the impact of sin, and biased because he’s fighting with God from birth.  Man can’t avoid distorting what he sees and thinks and feels.  Even “objective” sensory observations can be misleading and subjectively misinterpreted.
The Christian knows he can’t rely on his fallen mind.  He humbly relies on what God has revealed based on the assumption that God will not mislead his people.  Christians don’t reject reason or tests for its truth claims, but man’s reason must be redeemed through faith in Christ (Ephesians 4:23; Colossians 3:10).
Evidence and logic can substantiate the truthfulness of Christianity’s claims through history, archeology, laws of evidence, logic, etc.  All are viable ways to discuss the truth claims of Christianity, yet it must be under the control of God’s word.  Augustine: “I believe so I can know.”
Understanding Our Time: Philosophy/defend
Chris StrattonTruth