Often the most troublesome, and most interesting, cases concerning what we are conscious of and the nature of the conscious subject are those concerning memory. Lost memories, recovered memories, false memories, transplanted memories, they all present their own problems for a theory of consciousness. When attempting to define the criteria for a subject to be the same person, to have the same consciousness, we often turn to the idea that one of them remembers being the other. And when determining whether a past experience was conscious the only unambiguous case seems to be when it can be remembered. What is it about memory that makes it so important?
To see why we must first distinguish the parts of the mind are part of what can be described as the conscious subject from the mind as a whole. Although at one point it was believed that the mind was completely open to introspection, and thus consciousness, this is an idea that few modern philosophers subscribe to. In fact it seems as if the bulk of the mind is best described as unconscious. Dispositions, unconscious thoughts and motivations, beliefs (vs. belief acts), these are some of the things that are part of the mind but not part of consciousness. So let us consider the available mind, consisting of the aspects of the mind that the subject is or can be consciously aware of, and the remaining, unconscious, mind as two distinct objects (even though they are obviously closely connected together).
What matters when considering questions about the identity of conscious beings over time and determining which experiences are conscious is the contents of the available mind. Why? Well because these are things that we consider best decided from a first person point of view. A conscious experience is one that someone at some time is aware of having, and thus is part of some available mind at some time. It seems like a contradiction to say that an experience is conscious and that at the same time the person whose experience it is is not conscious of it. Similarly, we think that since the available mind includes all the information that is part of consciousness it defines who the conscious subject is, and thus that a theory concerning the identity of a conscious subject over time must rest solely on the available mind. The alteration of something unconscious, such as a disposition, might change the person (i.e. the whole mind) but it can’t affect the conscious subject (excluding of course the effects of that disposition that later become available to the conscious subject), and if unconscious features can’t affect the subject clearly it can’t distinguish them, and so it is impossible to use such unconscious features when constructing a theory about what it means to be the same conscious subject.
Thus we must construct theories about what makes an experience conscious and what makes two conscious subjects at different times the same using only the available mind. Consider first the identity of the conscious subject over time. Clearly identity over time can’t be defined in terms of the current experience, since what is currently experienced is extremely variable, and there is no guarantee that two different people couldn’t have the same, or very similar, experiences*. This leaves us with the two other components of the available mind, memories and facts (specifically facts about the self), to construct our definition with. Two parts? Interestingly neuroscience has revealed that facts are simply another kind of memory (facts are a manifestation of what is called semantic memory, in contrast to what we normally think of as memory which is called episodic memory). So really all we are left with is some form of memory, and thus we end up with theses such as Locke’s, which define identity over time in terms of shared a memories or containment in memory (and given our modern understanding we accept that those memories may be both fact memories and episodic memories).
The importance of memory in determining which experiences are conscious may be harder to see. Let us consider a conscious subject at a specific moment in time. Obviously we can determine that the current experience being had by this subject is conscious, since it is part of the available mind. But what about past experiences, how are we to determine if they were conscious to this subject? Well we must use our definition of identity over time, and see if that past experience was, at some moment, the current experience for a conscious subject which is the same as the conscious subject we are considering, as determined by our theory about identity over time. But, because any proposed theory about identity over time must rest solely on memories, we can only deduce from the conscious subject at the specific moment that previous conscious subjects existed which had as experiences the events that the current conscious subject remembers. And thus we can claim that only experiences that the subject remembers were necessarily conscious. But, you may object, there may be many other experiences that were had by past subjects that are identical (in the over time sense) to this one, and thus should be considered conscious for this subject. However, as mentioned above, what is conscious is something that is determined subjectively, and the subject at a given moment does not have access to the objective record of what experiences they had, they only know that they remember having some experiences. This is, of course, not to deny that the experiences that didn’t make it into memory were conscious to the subject, just that given the subject at some specific moment they were not necessarily conscious to that subject, it is a contingent fact that can be uncovered only through investigation into what really did happen at past times.
Thus, ultimately, our judgments about the identity of conscious subjects over time, and which past experiences were conscious, rest on memory, and so such unusual situations such false memories, transplanted memories, ect present us with problems. Specifically they present an account of identity over time based on memory with problems, and thus are problems for judgments about past experiences as well, since those judgments rest to some degree on judgments about identity over time. What these problems really reveal, in my opinion, is that you can’t successfully construct an account of identity over time using memory, or really any criterion. Thus thinking about an experience as conscious makes sense only when thinking about it being conscious to an individual at the time when it occurs, to think that a past experience can be conscious for some subject that exists now is simply a misguided way of thinking. I will, however, leave my criticisms concerning theories of identity over time for a later date.
* Admittedly this may be simplifying experience too much, since as I have argued in pervious posts experience comes loaded with concepts and information about the self. However, the possibility that this embedded information can serve as the basis for identity of the conscious subject over time can dealt with as simply a different way of expressing a fact about the self.