We know things in a variety of ways--intuition, sensory experience, inductive reasoning, deductive reasoning, etc. I was thinking today about memory. I used to list memory as one among several other methods of having knowledge. But as I was thinking about it today, I realized that memory is necessary for the majority of what we know or believe. And it's necessary to function in our day to day lives. This is interesting to me because people say that memory is "notoriously unreliable." I don't think people think about how much we actually rely on memory.
Most of what we know isn't based simply on sensory experience, science, reading, observing, etc. Rather, it's based on our memory of having experienced these things. What you know at this moment is based on something you experienced in the past. If we couldn't rely on at least the general reliability of our memories, we couldn't know anything other than what we are experiencing in the present moment. We couldn't even know that memory is notoriously unreliable. How does anybody know that memory is notoriously unreliable? Presumably, they know it because of something they read, heard, or experienced in the past. In other words, they are counting on those memories to be reliable.
But memory is important for an even more mundane reason. You couldn't function in your day to day life without being able to rely on your memory. Imagine trying to just have a conversation without the use of your memory. You couldn't respond to what your buddy just said because you wouldn't remember it. And you couldn't even get through your own sentence without forgetting what you were wanting to say. If you ever made it to the end of your sentence, you wouldn't know what you just said because you wouldn't remember how the sentence started.
And where would you go to get food? You can't just know, instinctively, that grocery stores exist and have food. You've got to rely on your memory to know that.
I don't think people would last long if memory really was unreliable. I think the reason people say memory is unreliable is because they're cherry picking. There are lots of times when our memories fail us, and we don't remember things exactly the way they happened. These moments stand out to us more than when our memories delivered accurate information, so we blow them out of proportion. The sentiment that memory is unreliable is understandable in that light, but I think the idea that our memories are generally unreliable is false. It's even a self-refuting claim unless the person wants to engage in special pleading by saying, "Except for my memories of when my memories and the memories of others failed."