Some time ago I suggested a challenge to persons I have encountered that maintain the controvesial thesis that we can know some propositions (e.g., that the God of Theism exists) with absolute certainty. Call this the absolute certainty thesis. I find this an extremely contentious view and raised a particular objection depending on considerations about memory. I want to take a first pass at summarizing the objection first by briefly mentioning the considerations that lead me to it.
Memory like perception, induction and testimony is a vital source of belief formation and knowledge. So much of what we take ourselves to know depends in part on memory. Memory among other things, preserves for us propositional content. It sort of works like an internal testifier, it saves certain beliefs to be used by its holder at a later time (this is so at least when speaking of factual memory, rather than episodic memory). Consider answering these questions: How long have you lived in Arizona? What is your name? What is the pythagorean theorem? Where is New Jersey in relation to California? How old are you? What did you eat for lunch? What is your blood type? When did you become a Christian? Who are your parents?
Your answers will undoubtedly depend importantly on your memory reporting certain facts, accurately. If we had no memories, our lives would be severely impoverished as instanced by persons who suffer severe memory loss. What may not be as obvious is that the faculty of memory plays an essential role in our assessing the merits of an argument. Is an argument valid? Is it sound? To answer these inquiries we need to employ inter alia, the faculty of memory. Consider the following fallacious argument:
1) All men are mortal.
2) Jones is not a man
3) Therefore, Jones is not mortal.
Notice that you have to work through the steps one by one. By the time you get to the conclusion you have to recall what premises preceded it to know whether the conclusion actually follows from the former. Moreover, you have to understand, recall and correctly employ basic rules of inference i.e., I must determine what logically follows from what and what doesn't, to make this judgment call. Notice that the longer the argument (viz., the more steps involved) the more difficult the task. Imagine if the argument had 20 pages of premises like some elaborate mathematical proof. Of course, you can keep referring back to the previous steps, but this doesn't avoid introducing memory. It seems an inalienable fact that our minds can focus only on one proposition at a time. So when I understand the conclusion, and then refer back to the first premise, to see if one relates to the other in the right sort of way, I have to remember the propositions being compared as well as the rules of inference governing arguments. And this is where the doubts creep in. What if as I appraise an argument, my memory only appears to me to be reliable but is in fact failing me? Note I am making a distinction between appearance or a seeming and the actuality or fact of the matter. Sometimes I swear I remember something that happened, only to be corrected by more reliable sources like written records. My memory does fail me. Details slip and change over time.
More fundamentally, memory qua faculty of preserving propositional content, seems to be contingently reliable. That is to say, it isn't a necessary truth that our memory is reliable either in general or on any given occasion. If this is right, there are really two interrelated problems here. The possibility of global memory failure: we cannot be sure that our memory is generally reliable and the possibility of local memory failure: on any given occasion where I employ my memory I cannot be sure that it is reliable. If it were a necessary truth that our memory was reliable in general, then we would never forget things. But as aforementioned, this seems contrary to our experience. We forget things all the time. Alternatively, if it were reliable on a particular occasion, necessarily (while not in general) then there must be some fact that makes this so. But I wonder what that could be. The question remains, how would we know that our memory was behaving on such an occasion rather than only appearing to us as so? It's important to keep in mind that this issue seems to show a problem with internalist theories of justification and knowledge. Internalists like Gangadean require that I be able to definitively determine that my methods of knowing are veridical. The very objective fact that my memory is correctly working on a given occasion can't ever lead to me knowing or having justification for my beliefs which are a result of this memorial process--I need further to be able to determine that my memory is actually working.
Here's a first pass at my objection against the possibility of knowledge with certainty (Gangadean's account of knowledge) from considerations of memory reliability:
1) If memory is contingently reliable, then on any given occasion where I employ my memory it is possible that my memory is failing me (i.e., not correctly reporting some fact).
2) Memory is contingently reliable.
3) Hence, on any given occasion where I employ my memory it is possible that my memory is failing me (i.e, not correctly reporting some fact).
4) Assessing the merits of any argument requires that I depend on my memory.
5) If 1), 2), 3) and 4), then any time I assess an argument, my memory could be failing me.
6) If 5) then we cannot be absolutely certain that any conclusion follows any argument.
It is a valid argument since it just consists of a series of Modus Ponens. Moreover, I think that argument is sound in that the premises seem uncontroversial. Of course, I'm not saying I know all of this with absolute certainty or anything like that. So there is no self-undermining going on in the above argument. If I were arguing that 6) follows with absolute certainty from 1) - 5), then I would be committing some intellectual indecency. But I do no such thing. I don't know with absolute certainty, that absolute certainty is not possible. I just think there are strong reasons to believe that absolute certainty is not possible.
We need proponents of the absolute certainty thesis to give us a persuasive argument that does not admit to any problems. My objection here is meant to show one problem against that thesis. If we cannot come up with a solution to the memory objection, then we cannot with propriety say we know anything with absolute certainty that depends on our memory to preserve facts for us. In subsequent posts I will consider some objections that were raised against my objection.
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