Consciousness and Personal Identity. An Investigation

Essay 2017 17 Pages

Philosophy - Practical (Ethics, Aesthetics, Culture, Nature, Right, ...)



In his 1984 book, Reasons and Persons, Derek Parfit develops a formulation of the famous teletransporter paradox to dissect our notions of personhood. Parfit asks the reader to imagine entering a teletransporter machine that induces sleep, records all of the relevant information about her physical composition, destroys her, and transmits the information to another planet to produce a precise replica of the individual out of new matter. It seems reasonable to expect that the replicated reader have all of the memories possessed before destruction, all of the same opinions, intentions, and subtle physical annoyances that accompany owning a physical body. Quite simply, this replica would appear to be identical to the original individual in all observable, qualitative aspects. Parfit suggests the possibility of a modified machine that not only preserves the existence of the original individual entering the machine, but is capable of infinitely duplicating exact physical replicas of the individual from new matter. From the seeming absurdity of considering oneself to be identical with a possibly infinite number of simultaneously existing entities, Parfit chooses to abandon the concept of sameness of person altogether.

Although I disagree with Parfit's conclusion, his thought experiment precisely extracts what I find to be the quintessential deficiency in many formulations of personal identity theory, both psychological and physical. In imagining a case of precise duplication, in spite of the proposed duplicate being identical in seemingly every qualitative respect, a simple question presents itself: when I enter the teletransporter and fall asleep, why should I expect to necessarily or even possibly wake up as any of these the duplicates? If I cannot anticipate the consequence of awaking, it appears as though the most essential and important aspect of my personhood, my own subjective experience, is omitted entirely. Though Parfit and other theorists may insist that what is truly important lies in the psychologically or physically preserved aspects of my duplicates, I find the prospect of seemingly ceasing to exist subjectively at all to be a far more significant consequence.2 Should any family member or friend of mine be precisely duplicated into numerous isolated individuals, I would not simply elect the most convenient among these to continue a social relationship with. I, and I believe many others who share this sentiment, would promptly seek out the original, hopefully resting in the teletransporter. Accommodating these foundational intuitions of what is valued in another person requires a uniquely determinative basis for personal identity in order to answer the question of what makes a person identical to herself over time.

In this essay, I will propose a framework for understanding personal identity based on the phenomenological basis of a continued stream of consciousness across time, borrowing from the concepts of William James and John Locke. In order to address the problems of observed absences or changes in consciousness across a person's lifespan, I will supplement this approach by arguing for a more precise understanding of conscious streams as an emergent phenomenon. I will then argue for the advantages of this approach relative to understandings of personal identity based on memory theory or biological criteria alone by explaining how it necessarily precludes the possibility of duplication. Finally, I will answer possible objections to the theory by confronting epistemological concerns that it raises for determining personal identity. This will include the argument that what makes a person identical over time is more significant to the concept than whether or not the fact of the matter may be reliably ascertained by outside observers.


John Locke, in his essay Of Identity and Diversity, may have been the first to explicitly theorize that personal identity is determined by a continued subjective consciousness. Locke's notion that personal identity derives from the sameness of consciousness over time, however, importantly includes a notion of memory being what connects one individual's conscious state with that of a past self. This mechanism has been thought to necessarily presuppose the notion of personhood in order to answer the question of what makes a person identical over time.[1] William James in his explorations of psychology even more deeply considers consciousness by hypothesizing the existence of a 'stream' of mental states that are fundamental to our sense of self.[2] As appealing as such notions may sound, however, some may argue that postulating a stream of consciousness raises more questions than it answers, at least in regards to laying an objective framework for personal identity. How is one able to make sense of possible cases of physical duplication or body switching by appeal to such an enigmatic concept alone after all? Where I wish to fundamentally deviate from these thinkers and many other theorists of personal identity is by appealing to a contemporary paradigm of emergentism within the philosophy of mind for the purpose of addressing a framework of personal identity.[3]

There are a variety of formulations of and arguments for emergentism about consciousness. My purpose here is not to argue in depth for a specific formulation of emergentism, but rather to demonstrate the theoretical utility of an emergentist perspective in establishing a coherent mechanism for understanding continuity of consciousness. A definition that will suffice for current purposes is that emergentism explains consciousness as a property of physical brain states that arises from the specific physical arrangements and relationship of the brain's neurobiological structure.

Furthermore, the view often maintains that consciousness itself cannot be explained by means of a reductionistic interpretation of the collective physical properties and constituents of the brain.

The essential benefit of adopting such a particular perspective within the philosophy of mind is, thus, allowing for a proposal of necessary and sufficient conditions for a numerical stream of consciousness. One of the central questions that arises when considering consciousness as a stream determinative of personal identity is how to explain an essential connectedness between the conscious state of a person at time Ti with the conscious state of a person at time T2. I would like to draw attention, however, to what is implicitly assumed when we ask such a question. 'T1 and T2' when attempting identify two points in time at which two hypothetical individuals exist appears to presuppose that a complete person can be properly said to exist at a discrete instance of time. When the implications of conscious states are considered, however, this framework for evaluating persons appears inadequate. It appears very clear that any psychological state that we commonly attribute to a person requires intervals of time in order for it to be coherently realized. Whether it be an emotion of anger, recollection of a slice of cake I consumed yesterday, or consideration of a belief; it appears to at least be highly suspect that any of these processes could be inferred to exist at any single point in time. From an emergentist perspective, it thus is necessary to consider these qualities as continuously emergent from a dynamic physical basis within the brain. With this perspective of necessary physical and mental continuity in mind, the question then arises of what kind of continuity is both necessary and sufficient for a numerical stream of consciousness. The mechanism I propose is recognition of the phenomenon of immanent causality of physical particles as necessarily existing throughout a continued stream of consciousness.[4]

Immanent causality as proposed by other writers might be summarized in the following way: if we consider for a moment, the possibility of a simple, partless entity, such as perhaps a fundamental subatomic particle, 8, at time Ti, and later at time T2, what might be said to account for the endurance of this numerically identical particle from T1 to time T2? If we wish to preclude the notion that the particle's persistence is due entirely to external causal factors which would allow for the contradictory possibility that the entity is annihilated and recreated exactly while still maintaining numerical identity, it appears that we necessarily require that the entity's persistence is due to its own intrinsic nature. Thus, the relation of a simple particle at time T2 with its numerically identical state at T1 would be an example of what I shall refer to after this point as immanent causality.[5]

If it is true that we value the notion of continuity of our particular stream of conscious experience of the world, it is necessary to explain why it is our particular stream of consciousness would appear to be distinct from the possibly infinite number of distinct duplicates proposed in a thought experiment like Parfit's teletransporter. The notion of immanent causality being a necessary mechanism for continuity of a stream of consciousness answers this question. Despite a proposed duplicate in Parfit's thought experiment having an identical arrangement of particles and even qualitatively identical psychological states, these entities could not be said to have the same numerical stream of consciousness due to the fact that the physical structures from which the conscious streams emerge do not have immanent causal connection between their emergent physical bases.8

Immanent causality, alone, however, although it may be a necessary condition, does not alone constitute a sufficient condition for determining whether a stream of conscious experience is numerically identical to another. For a sufficient condition, I will appeal to the proposed metaphysical nature of emergent systems in terms of the sufficient conditions postulated that make them distinct from systems of ordinary matter without emergent properties. Namely, a composite of metaphysically simple particles may be said to be emergent if and only if the properties of the composite as a whole cannot be explained in terms of the properties of its constituent particles.

Furthermore, if and only if this is the case, the metaphysical composite of simples may be said to possess metaphysically emergent primitive properties of its own, due to the fact that these properties, by definition, could not have arisen in any of the simples without the particular structure of the composite. If a stream of consciousness is considered to be an example of these emergent properties, it then follows that an entity possesses the same emergent property of a stream of consciousness if and only if it bears the same essential composite physical structure necessary to have the stream emerge as a metaphysically primitive entity. Importantly, however, because the emergence of the stream of consciousness appears to continuous such that it cannot coherently be thought to exist at any discrete point in time, it does not seem necessary for the structure of the composite to consist of precisely the same numerical particles. So long as a sufficient physical structure for the emergence is intact, it does not appear necessary for any one individual simple particle to always be present, and possible for individual simples to be replaced, so long as the same essentially dynamic physical structure of the brain exists for conscious emergence.[6]

From evaluation of Parfit's thought experiment, we thus arrive at the implication that an improved account of personal identity is that Person A is the same as Person B if and only if each have the same numerical stream of consciousness. Unlike many psychologically oriented theories of personal identity, consideration of a numerical


[1] Locke, John. "Appendix One. “Of Identity and Diversity” An Essay concerning Human Understanding." Locke on Personal Identity: Consciousness and Concernment, 2014. doi: 10.1515/9781400851843-023.

[2] James, William. Talks to teachers on psychology and to students on some of life's ideals.

North Charleston, SC: Createspace, 2016.

[3] O'Connor, Timothy, and Hong Yu Wong. "Emergent Properties." Stanford Encyclopedia of Philosophy. September 24, 2002. Accessed April 28, 2017. https://plato.stanford.edu/ entries /properties-emergent /.

[4] Schaffer, Jonathan. "The Metaphysics of Causation." Stanford Encyclopedia of Philosophy. February 02, 2003. Accessed April 28, 2017. https://plato.stanford.edu/entries/causation- metaphysics/.

[5] O'connor, Timothy, and Jonathan D. Jacobs. "Emergent Individuals and the Resurrection." European Journal for Philosophy of Religion 2, no. 2 (2010): 69. doi:10.24204/ejpr.v2i2.368.

[6] O'connor, Timothy, and Jonathan D. Jacobs. "Emergent Individuals and the Resurrection." European Journal for Philosophy of Religion 2, no. 2 (2010): 69. doi:10.24204/ejpr.v2i2.368.


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Indiana University – College of Arts and Sciences - Philosophy Department
Personal Identity Metaphysics Philosophy Causality Psychological Continuity Consciousness Derek Parfit Theoretical Framework Tim O'Connor



Title: Consciousness and Personal Identity. An Investigation