Essay, Book II Ch.XXVII
Locke points out that personal identity is not the mere unity of substance or material parts, since variations of matter, or even shape, do not necessarily alter the identity if they still partake of the same life-process. This sounds like Locke's notion of personal identity is merely nominal, that identity is merely `that to which' matter and thoughts refer - "the same continued life." But Locke goes on to say that "to find wherein personal identity consists, we must consider what `person' stands for... a thinking intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing, in different times and places (10)." This requires consciousness of perception, or perceiving that one perceives. My identity, then, is this same life-process perceiving, thinking, and reflecting, known as "I".
Having the same consciousness "makes a man be himself to himself (11): it is the requirement for identity. Consciousness, though, is not always continuous. It is often interrupted by forgetfulness, or sleep. So, how is this present consciousness known to be the same consciousness of the past [the past "me"] ?
This is determined by the contents of consciousness, that is, by the particular qualities and experiences of existence of which one is conscious. In other words, there are qualities and events of my consciousness that are particular only to me, and those of your consciousness which are not particular to me. If I am conscious of the sum of what you are conscious of, or what you have been conscious of in the past, then there is no perceptible difference between our identities.
Since identity is based on consciousness, and consciousness is of either circumstance or thought, then identity is based on particular experiences. It is based on personal memory or history. I could only claim to be the same person as John Locke around 1668, if I am conscious of the same personal memories as he. Otherwise; saying we are identical persons is meaningless if I possess no memory of that particular existence. I could only then say that we are identical in being conscious thinking animals, but this generalization is meaningless in terms of the question of `personal' identity. And obviously, we are not the same body, even if we closely resembled each other. So, what is personal identity is consciousness of the personal history, or memory, of this particular continuing life-process (me) thinking and reflecting in this particular way with this particular content of experience.
Locke demands that the personal history be conscious, because if this is not required then I could claim to be the same identity as anyone else while assuming that I have forgotten about "our" personal history. I could claim to be the reincarnation of John Locke, claiming to have the same identity, while excusing myself for not remembering anything about "my" life in 1668. So; consciousness of history, or actual memories, are required in order to speak of identity in a meaningful way. Yet, I don't remember anything about early experiences, such as when I was five years old or younger. Even if I did, these images could very well be those suggested by others or by TV. Since I don't remember, and can't remember even when I try, does this mean I am not the same person now as then, or that my identity has changed? There seems to be a problem with this criteria of identity, if my singular identity depends on just what I am conscious of at this moment, or on just what I am capable of remembering at this moment.
And even though my particular history or memory is what identifies me as me -- what is it that connects these memories into one identity, besides that they all refer, in some way, to this body called Matt ? Is Matt, not just the body Matt, the same consciousness or the same identity all throughout this history ? Or, what makes me think that I am the same `I', or the same person, now as then, or that there IS any such unity of self-identity, besides just a bundle of experiences gotten in some way from this body-in-existence ?
TREATISE Part IV, sec. VI
Self, or personal identity, is not any one impression. There is no distinct and continuous impression or experience of a single-identified `self', and the idea of a `single self' cannot be derived from the successive multiplicity and variability of impressions. Thus, the idea of `self' is ungrounded by experience or reflection. All that is experienced are several impressions or some series of ideas, sometimes having resemblance, or a sense of continuity to each other, but not always. A `self' underlying or uniting such successive different impressions and ideas cannot be found empirically. At the most, this `self' is "that to which our several impressions and ideas are supposed to have a reference."
Any consciousness, whatsoever, is a perception of the mind, an impression or a reflection or an idea/feeling. Nothing else is possible. Perception is always `of something', and is not `of that which perceives'. Any `self', then, is "but a bundle or collection of different perceptions, which succeed each other... and are in a perpetual flux and movement." Hume makes the analogy that "the mind is a kind of theatre, where several impressions make their appearance."
What we might question is whether these several and different impressions have any single similarity, which would unify them as being `of one single self'. We often make up the fiction of the invariable, or mysterious, `self', in order to believe in our uninterrupted continuous existence, in spite of the multi-various kinds of impressions on our mind over many interrupted moments. Some similarity or invariance should not be considered a rationally necessity for the unification of this variety of reflective experiences. In other words, we should not posit a `self' just in order to justify our psychological hope for self unity, or singular identity, if the empirical evidence points to non-unified and interrupted self-existence.
Is there something invariable and continuous about these impressions, then, which can justify the notion of one invariable personal identity, or `self'? What could give objects or perceptions a common, single identity is the invariability of certain properties of each. Common, resembling properties of all reflections cannot easily be found, except maybe in the circular supposition of a unifying `self' having these reflections and impressions. There needs to be some kind of invariable relation connecting these different and distinct impressions with one another. It is this `relation' that "facilitates the transition of the mind from one object to another, and renders its passage as smooth as if it contemplated one continuous object." Hume also says, "Identity depends on the relation of ideas; and these relations produce identity, by means of that easy transition they occasion."
Hume believes it is this association or relation among objects of refection that causes the mistake of supposing the idea of `self' or identity, instead of recognizing just the relation. The relation of parts or of succession in experience is but a quality, and not an identity. To say objects are related is not to mean they are the same, or even of the same `thing' (ie., self). Being related does not even necessarily imply contiguity or resemblance; but then it must imply the third possibility of relation, which is causation, or of `one thing leading to another'.
In this relation of causation, there is no need for invariability of resemblance, or a need for common properties of thje objects of perception. The relation of succession, or of one perception following another, gives a kind of illusion about causation, that because of succession there is a necessary relation between the perceptions succeeding each other; when in fact, there is no necessary connection or causation involved in succession. The only relation is `one following the other', and because we experience such a succession, using memory, the imagination naturally associates these succeeding and semi-continuous impressions with each other, in way that gives a feeling of one, singular self, or personal identity.
There is, then, no necessary connection or interdependence between such sequential impressions; only that they flow one to another, and are all contained in this memory, and in this body. It seems also requisite that any changes or variability of impressions succeeding one another be NOT too sudden or too variable. The variability could be vast over time, but cannot be too sudden between one impression following another. For example, the fiction of my singular identity cannot be maintained if at one moment I'm playing on guitar my own written love song, and then suddenly I feel myself as a karate master and split the guitar with one blow. Upon reflection, I might theorize as to why `I' (this one self identity) would so radically change in one moment, but there would be good reason to maybe suppose a "split personality" or two distinct identities.
Our personal history seems the best possible evidence for a singular self or identity; but, even granting the correctness of personal memories, there could just as well be many identities involved in this history of this body named Matt, since relational unity is not always apparent, and there has often been "struggles within".
Hume sees nothing that necessarily binds together our many distinctly different perceptions or reflections. There is nothing in them, or relating with them, that makes them of one identity. We only feel the connexion, never observing it. The connexion is merely a feeling or association in the imagination, due to the continual succession of perceptions. These perceptions seem to continually follow one another; so, an association is made based on succession; and thus the presumption of one unified self identity.
Hume says that "identity is nothing really belonging to these
different perceptions, and uniting them together; but is merely a
quality which we attribute to them, because of the union of their ideas
in the imagination, when we reflect upon them." We suppose that all
these perceptions fit together by some kind of connexion, or unifying
principle which is the underlying reason for such a succession. But,
the only connexion, and the only unifying principle, is that connexion
made in the imagination through associating (or unifying) successive
perceptions together, for no other reason than their being successive,
or that they possess the quality of succession.
The fact that one perception follows another does not say much about personal identity. There seems to be a continuance of perceptions in "my" experience. These successive perceptions constitute what "I" call "my" experience. These many experiences following each other are what constitute "my" conscious life-process, such that these experiences are particularly mine. "I" is the referential subject "having" these particular experiences and capable of remembering these experiences. Memory, or the power of recollection, is of course essential to this identity of me. [And memory is presupposed to have some significant resemblance to the manner in which impressions and reflections originally occurred. The fact that these experiences are sequential, or naturally follow one another, is essential to identity, but not at all sufficient. Nobody would say it is.
Of greater importance is that all these experiences belong to one conscious being, or at least to one semi-conscious body. They cannot be proven to possess a unity, just because they follow one another; but the fact that they all belong to one faculty of memory, the recollections of which a power, "I", seem to have some control over, does give this bundle of memories a theoretical unity. All of these experiences, including the present experience, are unified together by the simple fact that there are no other experiences known, now or ever. One can infer that other experiences "exist", or have a psychological reality, or that there are, and have been, other memories besides those I am capable of recollecting; but, nonetheless, the only experiences had or known or recollected, as much as "I" am capable of remembering, are "my" experiences. Besides the inference that others have other experiences, there are no other experiences known or remembered besides those "I" have or that "I" remember. Being that all these constitute one complete set, they all constitute a unity, they all are related. This unity is what is meant by the assertion that "they all are mine." "Mine" is the predicate quality of unity.
Another point to be made is that, even though all these successive perceptions do not, with any apparency, resemble each other; resemblances are more apparent with my reflections about "myself" or my activities. There are attributes of this remembered and present life-process, called Matt, which are unique (peculiar) and relatively constant, and which do resemble each other from certain theoretical frameworks. Certain reactions, emotional responses, and habitual behavior patterns repeat themselves regularly. These are what make this person, Matt, now resemble the various remembered persons of Matt. I recognize myself in the past, in the memory, because there is a resemblance, there is some connecting pattern, not just of the body but of the mind and behavior as well. If you think I'm an idiot now -- you should of known me before!
Not only are there common patterns and resemblances with emotional responses and behavior, but with thoughts and ideas as well. If a detached observer were able to observe or experience what occurs in various minds, and was able to experience my mind, or were to "walk in my shoes", or experience how it is to be this mind/body called Matt, such an observer would most likely be able to distinguish me from other body/minds, would be able to recognize me out of others. This is because there are many attributes, habitual responses, and ways of thinking which are peculiar to me. You'd be shocked to know just how peculiar I am! Likewise, I would probably be shocked to experience how it is to be you.
On the other hand (or mind?), there are probably many attributes, responses, and thoughts, common to most persons. We have common worries, common desires, common perceptions, and thoughts and reflections. In fact, the average person is not all that unique. Just as dog or baby experiences are mostly of a common kind, the simple, average American probably has thoughts which could just as well be other people thoughts, and never know it. And the most universal thought or reflection might be that "I exist", or "I am thinking", or "I am uniquely me." So; personal identity ranges from being a collective identity to being a more peculiar identity, the differences being mostly due to body-types, social circumstances, early development, on-going education, and reflective thinking.
Also there is a loose continuance and development throughout this
known or remembered process. I remember wondering about certain things,
I remember being confused, I remember struggling, and I also remember
learning, solving, and achieving in areas that before I could not. This
is the history of my growth, emotional and mental, and it is peculiar
to me. So, there is a connection, which is more than just the bundle
itself, or the succession, and this does have some resemblance and
continuity. Thus; I am I, however peculiar, however often disconnected
and contradictory. I assert the unity of this body and a loose unity of
this mind. And maybe the power of assertion itself, in this moment, is
all that can truly be asserted as "I".