The Problem of Memory Knowledge
Here, I explain how memory beliefs are justified.*
I. Problem
Here’s something interesting about our beliefs. Almost all of our beliefs rely on memory, and in many (most?) cases, we don’t remember the justification for those beliefs; we only remember the belief itself. For instance, I know that the Constitution was written in 1787, but I have no memory of how or when I learned that. I guess I learned it from some adult when I was a child, but I don’t remember when that happened. I think I’ve also heard it corroborated many times since then, but I don’t specifically remember any of those occasions either.
So if someone asks me for a justification for this belief, I have almost nothing to offer. Nothing beyond, “I seem to remember that.” Sounds pretty lame. Since I don’t now know my original justification, do I, as of now, have any justification? (Is the memory itself a justification?)
This question is important since this is how many, probably most, of our beliefs are. Yet many traditional epistemological theories fail to deal with it.
II. Two False Accounts
First theory
Memory experiences are themselves a source of justification. If you seem to remember that P, that experience itself gives you a reason for believing P. (Of course it’s defeasible, so you have to lack specific grounds for doubt.)
Problem: Suppose I irrationally adopt the belief that my great great grandfather was Abraham Lincoln. Let this be acquired in whatever you would regard as a paradigmatically irrational manner (but stipulate that I have no specific evidence against the belief). Then suppose I subsequently forget how I acquired the belief. According to the above theory, as soon as I forget how I acquired this irrational belief (while still remembering the content of the belief), it immediately becomes rational. That seems wrong.
Second theory
Memory experiences are not a source of justification. They are only a way of preserving the original justification you had for a belief when you acquired it. This is true even if you forget how you acquired the belief – it is still justified by whatever originally justified it. E.g., my current belief that the Constitution was written in 1787 is justified by the testimony of whoever told me that, even though I don’t remember who it was.
In the Lincoln case above, the belief never becomes justified because there was no original justification for the belief, hence nothing to preserve.
Problem: Consider Bertrand Russell’s five-minute hypothesis: Suppose that God just made the world 5 minutes ago, with everything in exactly the state that it was in then – including fossils already buried in the ground, false memories already encoded in our brains, etc. In that scenario, everyone would believe exactly what they believe in the actual world. E.g., I’d still think that I went to UC Berkeley around 1990, due to the false memories God planted in my mind.
According to the above theory, all these beliefs would be unjustified, and hence, we would all be irrational to think all these seemingly normal things. That’s because memory isn’t a source of justification, and we’d have no other source of justification for our beliefs since we would have never originally learned them by the normal (non-memory) means.
This seems wrong. Rather, if God deceived us in that way, it would be totally reasonable for us to believe all the things that a rational person believes in our current world.
This is a puzzle. It seems as if we just showed that memory isn’t a source of justification (in the Abraham Lincoln example), and then that memory is a source of justification (in the five-minute example).
III. A Solution
First, let’s distinguish two kinds of justification:
If you don’t currently have a belief about P, you can have justification for acquiring one.
If you currently have a belief about P, you can have justification for retaining it.
Notice how those things are different.
Now here’s my theory:
When we say a belief is “justified” full stop, we mean that (i) the subject was justified in acquiring that belief at some time, and (ii) the subject has been justified in retaining the belief since then.
Remembering a belief, while lacking any specific reasons for doubting it, counts as a justified way of retaining the belief.
Having a seeming memory that P also counts as a justified way of acquiring a belief, if indeed one acquires the belief that P in that way.
This theory explains the intuitive judgments about the cases.
a. The Abraham Lincoln case: the belief was acquired in an unjustified manner (by stipulation), so the belief is overall unjustified according to (1), even though it was retained in a justified manner after its initial acquisition.
b. The Five Minute case: Here, the beliefs are originally acquired by memory (by having false memories implanted in us 5 minutes ago), which counts as a justified acquisition (per (3)). They were also justifiedly retained since that time (i.e., for the last 5 minutes) due to the normal operation of memory (per (2)). So they’re overall justified.
c. My belief about the Constitution: Here, the belief (I assume) was acquired in a rational manner. Since I’ve retained it in memory since then without having any specific grounds for doubting it, it counts as also being retained in a rational manner (per (2)). So it’s overall justified (per (1)).
IV. A Complication
Q: What if someone initially acquires a belief for bad reasons, then later learns good reasons that would suffice to justify it?
Ex.: Suppose I think that Trump is going to be the 47th President. I adopt this belief initially out of spite, because it annoys Democrats. So this is unjustified and not knowledge. Then, on election night, Trump actually wins. I see reports from all the news networks saying that Trump is the winner. I watch Biden’s concession speech. Etc.
Problem: The formulation in (III) above seems to say that the belief continues to be unjustified, since it was acquired in an irrational manner. If knowledge requires justification, then I would continue to not know that Trump will be the 47th President even after I’ve watched the election results. This seems wrong. After I watch Biden’s concession speech, etc., surely then I know (and have a justified belief about) who is going to be the 47th President.
Solution: Modify/interpret condition (1) in sec. III as follows: your belief is justified provided that there was some time at which you had justification for acquiring it (even if that was later than when you first acquired it), and that justification became at that time part of your basis for holding the belief. This does not bring back the “Abraham Lincoln” belief as justified, because a memory experience still only counts as justification if it is the original way the belief is acquired (per (3)).
[* See “The Problem of Memory Knowledge,” Pacific Philosophical Quarterly 80 (1999): 346-57.]