In his work The Stream of Thought, James tackles the fundamental notions of how we come to understand the matters of our own consciousness (which he defines as the multiplicity of objects and relations). For James, consciousness can only be one's own (that no two consciousness can ever be exactly identical), and consciousness "goes on."
James is discontent with psychologists who deem consciousness through an unfounded verisimilitude with sensations. Sensations, according to James, cannot stand by themselves, for they are necessary results of discriminative attention.
James then sets the rest of his work clarifying what he means by consciousness (that are unlike sensations that are mere results of discriminations) "goes on" in the human mind.
First, James defines thought as a "personal form" to indicate the peculiar quality of each person's consciousness. Thoughts, for James, "belong" together, but belong together in one's own mind. No one's 'thoughts' are separate from one another, for one's own thoughts necessarily belong to one's other thoughts. The only states of consciousness for James, are located in the "personal consciousness" of one's own minds, selves, the "concrete, particular I's and you's" in which no one can have direct sight of thought into another person's consciousness.
James describes that this phenomenon is "absolute insulation and irreducible pluralism."
Secondly, James contends that the thought constantly changes for "that which takes place in sensible intervals of time" can never be "identical with what it was before."
He presents his argument for this claim by postulating that whether we think or do not think, we always have a succession of different feelings. He moreover explains that when we actually pay close attention to the matter, we will come to realize that we do not experience the same bodily sensation twice in perceiving an object.
What stays the same may be the "object" such as hearing the same note over and over again or seeing the same quality of green as the grass. However, we do not realize that we experience these objects differently when we do not attend to sensations as "subjective facts" and instead use them merely as stepping stones to pass over to the recognition of the realities (the object).
We are prone to not attend to the different ways in which the same things look/sound/smell at different distances under different circumstances, for we are inclined to ascertain the "sameness of things."
But James beckons us to recall the ways in which the same object may appear differently to us as we are sleepy or awake, hungry or full, fresh or tired, or as we go through different stages in life from childhood to adulthood. Our feelings towards the same object changes as we pass from one age to another or when we are in "different organic moods."
James goes on to say that this indicates that every sensation does in fact correspond to some cerebral action, and there is no such thing as an "identical sensation" for it would require an unmodified brain and unmodified feeling which is a physiological impossibility.
In other words, our state of mind is never precisely the same, and our thoughts, feelings, and the overall experience of an object differ in each circumstance, though we may be inattentive to the changes.
James builds up a case for his phenomenology:
The subjective experiences of the same object differently, and experience remolds us every moment, and our mental reaction on every given thing is a resultant of our experience of the whole world up to that date.
Every brain-state is partly determined by the nature of this entire past succession. Each present-brain state is a record, in which the Omniscient eye will read all the foregone history of its owner. Each present is altered by the past success and the organ has been left at that moment by all it has gone through in the past. Therefore, no two ideas can be exactly the same for each idea belongs to a specific place in time.
To even believe in the possibility of a permanently existing "idea" is to only be concerned with the "facts" the mental states reveal, rather than the complexities of the mental states themselves.
Thirdly, James points to the fact that within each personal consciousness, thought is continuous (that is, without break, crack, or division).
What we may consider "breaches" in a single mind are mere interruptions or time-gaps, which are breaks in the quality or the content of the thought that may seem abrupt.
However, James nonetheless clarifies that the thoughts within each personal consciousness are continuous, for even when there is a time-gap, the consciousness after feels as if it belonged together with the consciousness before, as another "part" of the "same self."
James also repudiates any type of "absolute" sense of abruptness in one's consciousness for there will be even a dim sense of continuity, the sense that parts are connected and belong together as part of a "common whole" which is the self whom all these thoughts belong to.
This phenomenon James calls, the community of the self, for one feels the warmth, intimacy, and immediacy of one's present thought that surely belongs to oneself. These qualities of warmth and intimacy to the self will also be connected to future considerations of thought, and past feelings also come with these qualities as the past also receives the greeting of the present mental state. The past, present, future all belong to a community of the self. Jameisan self is connected by psychological connectedness between the past, present, and future self as a coherent whole that fundamentally differs from Derek Parfit's successive selves. For example, Parfit denies that there can ever be a coherent self for there is no such thing as a "permanent self." What exists in the present brain state can only be classified as the present "self" and the next brain state is a distinct self. The chain of successive selves (notice, he uses the metaphor chain unlike Jamesian metaphor of the stream that flows together) are linked together through "memory," yet each self is distinct from previous and future self. There is no "person" that all these selves share, for a collective "I" is merely an illusion.
Rather than Jamesian psychological connectedness of selves via continuity in thought, Parfit denies that there can be continuity and connectedness enclosed within one single life. Instead, his notion of successive selves are made possible by the degree of psychological connectedness to others. What Parfit is suggesting here is a much more tenuous "I" than the atomistic sense of individuality. Rather than a Jamesian community of "self" Parfit proposes a "community of selves' that are necessary for these successive selves to have any sort of meaning.
On the whole, I can understand why Jamesian notion of the self as continuous and coherent can receive criticisms from many philosophers whose notion of the self is necessarily contingent upon the contexts and communities that will allow for the formation of selfhood. Is selfhood a given? Is consciousness that is continuous made possible by efforts of the will? For what can be said about situations of trauma in which there is such an absolute sense of abruptness in which the qualities of "warmth and intimacy" of thought to the self is no longer possible? For the thoughts that the self once had no longer has any vestiges of a connection to the present self? To this, I may agree with Parfit in that successive selves seem to fit better than a coherent, continuous self. Though, I also do not believe all individuals would necessarily go through life in the way Parfit describes it. One's experience of life, depending on the severity of trauma and trauma's impact on the psyche, can be a mixture of continuous and successive selves.