This paper examines two major philosophical theories of personal identity: John Locke's memory theory and David Hume's bundle theory. Locke argues that personal identity is rooted in memory and a stable set of physical attributes that persist through time, separating identity from morality and lived experience. Hume, by contrast, conceives of personal identity as a dynamic succession of perceptions that integrates all aspects of human experience. The paper also considers how bundle theory handles split-brain cases, where two independent fields of perception coexist within one person. Ultimately, the paper evaluates both theories and argues that Hume's bundle theory offers a more complete and empirically defensible account of personal identity.
Locke's theory of personal identity entails what is known as the memory theory. According to Locke, the basic idea behind the theory is that no two similar things can co-exist in the same spatial environment. In terms of personal identity, each person has a spatio-temporal history, embedded in memory, that is unique within the environment they share with others.
Locke's view is closely intertwined with his views on religion. God is a being that exists unchanged and simultaneously in both spatial and temporal environments. The memory theory of personal identity therefore does not apply to him, as he is infinite and unchanging. Finite beings, on the other hand, change and are changed by their environment. They are the sum of their unique experiences as they move through space and time toward their end. Each finite being thus exists as distinct from other finite beings — hence the uniqueness of each — and occupies a space that is unique while coexisting with others of its kind.
Personal identity, as Locke conceives it, is rooted neither in rationality nor in a presumed soul. Instead, identity is defined in terms of a living animal within a specific species, possessing a number of particular defining characteristics. Locke thus defines a human being in terms of function rather than underlying nature. The identity of a conscious person is therefore independent of the substance or substances composing that person at any given time.
Moral reasoning is somewhat simplified by this view, since morality is treated as independent of personal identity. Moral accountability becomes a question not of personal identity but a separate issue altogether. The memory theory thus simplifies questions of morality: because memory is held to compose personal identity, a person should have no difficulty drawing on their past in order to adhere to moral standards in the present and the future.
Hume, in contrast to Locke, saw personal identity as part of a greater whole in which all aspects of humanity are integrated with the personality itself. Personal identity, according to Hume's bundle theory, is a succession of perceptions that changes and grows as the human being moves through life. It is therefore not a static set of characteristics, whereas Locke's theory presupposes a basic, unchanging set of attributes regardless of surface change and growth.
Hume describes these changes as a succession of perceptions that evolve as human beings grow and develop. As physical growth occurs, so does perception, and personal identity is thus closely related to this succession. According to this view, the personality of a person as a child is not the same as that of the same person at twenty years of age, or indeed in old age. Personal identity is therefore variable — a view that contrasts sharply with Locke's conception of identity as static. Hume further argues that the variables inherent in identity must be understood in relation to the whole in order to determine personality in its entirety.
Hume also addresses the distinction between rapid and gradual change. If any part of the body or personality changes suddenly, the perceived identity changes rapidly as well. The same is not true of gradual change, such as physical and spiritual growth. This may in fact explain why Locke separated physical identity from all other aspects of humanity: the change perceived in a growing person is too slow to register as significant, creating the assumption that the basic attribute set remains unchanged. Hume describes this as the continued perception of gradual change producing the illusion that identity is static. According to Hume, this illusion accounts for the fact that a person, animal, or plant can grow and change without appearing to lose a fundamental personal identity, even as the body is entirely transformed over time.
"Bundle theory applied to split-brain patient consciousness"
"Hume's integrated, dynamic model surpasses Locke's static view"
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