If experience is evidence, the main source of justification of these past events is our memory. Memory is a record of true propositions. It can be reliable, or not. But to remember something is to believe it to be true. And our memory serves as the path to all knowledge by way of this justification.
We are creatures of truth, and our memories serve as evidence of our past.
My memory has seemed to wane recently, and I’ve learned how dependent I was on it. When I lose justification about whether I said something or not, did something or not, I lose confidence. And if I don’t have internal justification with my memory, I seek external validation.
I’d be afraid to say something because I can’t remember whether I’ve already said it or not. I’d be scared to do something because I can’t remember if I’ve already done it or not. So I’d play a game of tact. I’d say it in a way that could be taken as my second time to say or do something.
Even facts that I know are based in memory. While my memory may not be the justification itself, it is the source of the justification. For example, I know that Mount Everest is the tallest mountain in the world. But how do I know that? I read it online. How did they know it?
If knowledge is justified true belief, what is it without the justification?
So if knowledge is based on this justification, our memory, mine is waning. I still know the same things, yet I have less and less confidence in them. I keep trying to justify the justification: refusing to accept my memory. Instead I look for further evidence or justification of the memory that I do have. I basically don’t trust that what’s in my mind matches what’s in reality. And without the justification, my knowledge is just beliefs. True beliefs, but beliefs nonetheless.