Plato’s cave analogy produces the conclusion that your perception of reality is your reality; because you are unable to perceive anything outside of your reality. Though perception is variable, therefore nothing is truly absolute or can be proven like this. Descartes asserts, “Only pure knowledge known by resources of reason can be totally reliable.” I would argue then, that reason is learned based on situation and environment, which changes for each person.
Every person perceives each situation differently, therefore, the reason is also variable. What anyone can know, is derived from information gathered, from observation of the world. Then used to draw a conclusion widely agreed upon, but since what we know comes from what we observe and what we have the ability to observe continues to progress, factors multiple and the prior knowledge expands, therefore, changing what you thought you knew.
Consequently what you are able to observe and claim to know how and what you will “know” in the future, will differ. That being said no one can ever truly know anything, because you know what you know until what you know changes so actually you never truly knew what you thought you did.