Parfit contrasts the Non-Reductionist and Reductionist Views of persons: the former holds that perso… — Derek Parfit

Parfit contrasts the Non-Reductionist and Reductionist Views of persons: the former holds that persons are separately existing entities (e.g. Cartesian Egos) whose identity over time is a further all-or-nothing fact that is what matters, whereas the latter holds that a person’s existence just consists in the existence and activity of brain, body, and mental/physical events, that personal identity over time is nothing over and above certain physical and psychological continuities describable impersonally, and that what matters are the relevant relations of connectedness and continuity rather than identity itself.

By Derek Parfit, from Les raisons et les personnes

Key Arguments

He sets out the Non-Reductionist View: 'On the Non-Reductionist View, a person is a separately existing entity, distinct from his brain and body, and his experiences. On the best-known version of this view, a person is a Cartesian Ego.'
He defines his Reductionist View: 'On the Reductionist View that I defend, persons exist. And a person is distinct from his brain and body, and his experiences. But persons are not separately existing entities.'
He characterizes a person’s existence on Reductionism as wholly constituted by lower-level facts: 'The existence of a person, during any period, just consists in the existence of his brain and body, and the thinking of his thoughts, and the doing of his deeds, and the occurrence of many other physical and mental events.'
He states that on the Reductionist View, 'personal identity just involves physical and psychological continuity. As I argued, both of these can be described in an impersonal way. These two kinds of continuity can be described without claiming that experiences are had by a person.'
He distinguishes what matters: 'A Reductionist also claims that personal identity is not what matters. Personal identity just involves certain kinds of connectedness and continuity, when these hold in a one-one form. These relations are what matter.'
By contrast, 'On the Non-Reductionist View, personal identity is what matters. And it does not just involve physical and psychological continuity. It is a separate further fact, which must, in every case, either hold completely, or not at all.'
He ties Non-Reductionism to a distinctive explanation of unity via ownership: 'Psychological unity is explained by ownership. The unity of consciousness at any time is explained by the fact that several experiences are being had by a person. And the unity of a person’s life is explained in the same way.'
He insists that these clusters of claims 'must, I have argued, stand or fall together', and notes that while 'the Non-Reductionist View might have been true' (e.g. if we had reincarnation evidence), 'there is in fact no good evidence for this view, and much evidence against it.'

Source Quotes

I distinguished two views about the nature of persons. On the Non-Reductionist View, a person is a separately existing entity, distinct from his brain and body, and his experiences. On the best-known version of this view, a person is a Cartesian Ego.

On the best-known version of this view, a person is a Cartesian Ego. On the Reductionist View that I defend, persons exist. And a person is distinct from his brain and body, and his experiences. But persons are not separately existing entities. The existence of a person, during any period, just consists in the existence of his brain and body, and the thinking of his thoughts, and the doing of his deeds, and the occurrence of many other physical and mental events.

But persons are not separately existing entities. The existence of a person, during any period, just consists in the existence of his brain and body, and the thinking of his thoughts, and the doing of his deeds, and the occurrence of many other physical and mental events. Since these views disagree about the nature of persons, they also disagree about the nature of personal identity over time.

Since these views disagree about the nature of persons, they also disagree about the nature of personal identity over time. On the Reductionist View, personal identity just involves physical and psychological continuity. As I argued, both of these can be described in an impersonal way. These two kinds of continuity can be described without claiming that experiences are had by a person.

These two kinds of continuity can be described without claiming that experiences are had by a person. A Reductionist also claims that personal identity is not what matters. Personal identity just involves certain kinds of connectedness and continuity, when these hold in a one-one form. These relations are what matter. On the Non-Reductionist View, personal identity is what matters.

These relations are what matter. On the Non-Reductionist View, personal identity is what matters. And it does not just involve physical and psychological continuity. It is a separate further fact, which must, in every case, either hold completely, or not at all. Psychological unity is explained by ownership.

And the unity of a person’s life is explained in the same way. These several claims must, I have argued, stand or fall together. I conceded that the Non-Reductionist View might have been true.

Key Concepts

On the Non-Reductionist View, a person is a separately existing entity, distinct from his brain and body, and his experiences.
On the Reductionist View that I defend, persons exist. And a person is distinct from his brain and body, and his experiences. But persons are not separately existing entities.
The existence of a person, during any period, just consists in the existence of his brain and body, and the thinking of his thoughts, and the doing of his deeds, and the occurrence of many other physical and mental events.
On the Reductionist View, personal identity just involves physical and psychological continuity. As I argued, both of these can be described in an impersonal way.
A Reductionist also claims that personal identity is not what matters. Personal identity just involves certain kinds of connectedness and continuity, when these hold in a one-one form. These relations are what matter.
On the Non-Reductionist View, personal identity is what matters. And it does not just involve physical and psychological continuity. It is a separate further fact, which must, in every case, either hold completely, or not at all.
These several claims must, I have argued, stand or fall together.

Context

Still near the beginning of Section 94, Parfit re-summarizes the two competing conceptions of persons and identity that structure earlier Parts III and IV, to set up the question of whether the Reductionist View can be believed.