HOW DO I KNOW? (based upon the writings of Chris Redford)

How do I know what is real?
Why do I believe what I believe?
What am I justified to believe?

For years, ancient Greek philosophers argued convincingly that we could know nothing with absolute certainty--that is, until Rene Descartes uttered, "I think, therefore I am." This is the only necessarily true statement that is beyond doubt.

Thus, even if one thinks, then one cannot necessarily justify the existence of other beings; but, if one thinks, one can justify one's own existence as a thinking being.

So, if I purge all of my beliefs and add back only those which I can justify, I can only justify my own existence because my perceptions can be inaccurate. For example, I have been asleep and believing that what was happening was really happening--only to awaken and find out that it was only a dream. Thus I could be dreaming about anything that I perceive to be true.

Therefore, other than knowing that I exist, I don't actually know that anyone or anything else exists so I have to make a presupposition (an assumption) and that presupposition is:

At least some of my perceptions (sight, sound, touch, taste, smell) are accurate--that is, that they reflect reality.

Of course, none of my perceptions are necessarily accurate but without this presupposition, I have nowhere to go epistemologically.

[Epistemology is the branch of philosophy that investigates what distinguishes justified belief from opinion.]

Without this presupposition, I can prove nothing to be absolutely true except that I myself exist (but only as a thinking being and only to myself), but I could not prove that anything else exists--not even to myself.

Thus, presupposing that at least some of my perceptions are accurate, how do I make conclusions about reality?

(1) I form beliefs about reality based on physical evidence.

(2) The strength of my beliefs should be directly proportional to the amount of evidence I have for them.

(3) If I ever doubt the validity of a conclusion that I make based on evidence, I can return to that evidence, re-examine it, and see if I come to the same conclusion.

Thus for beliefs to be justified they must be grounded in evidence. Beliefs that have more evidence are more justified, and beliefs that have less evidence are less justified.

(4) It would be unfeasible for me to personally collect all the evidence I use for my beliefs. However, I can gather new types of evidence in the form of the multimedia and testimonies given by other people. But, I cannot place as much confidence in multimedia and testimonies as I can in direct physical evidence.

If I want to maximize my confidence in the physical evidence given to me by other people, I should use such evidence as a starting point and then investigate such evidence myself.

If I refuse to do this with any such belief, I must accept that my confidence is lower than it would be if I had verified such beliefs myself.