The Appeal to Full Relativity poses a dilemma: either reasons cannot be relative (in which case Nage… — Derek Parfit

The Appeal to Full Relativity poses a dilemma: either reasons cannot be relative (in which case Nagel’s Neutralism wins and we must reject Self-interest, Present-aim, and most of common-sense morality), or reasons can be relative, in which case they can be fully relative to the agent at the time of acting, and temporal neutrality—and thus the S-theorist’s Second Reply—cannot be sustained.

By Derek Parfit, from Les raisons et les personnes

Key Arguments

Parfit formulates one part of the Appeal as '(P1), the claim that, if reasons can be agent-relative, they can be fully relative: relative to the agent at the time of acting.' He frames the main disjunction: 'Either reasons can be relative, or they cannot.'
On the first horn, 'If they cannot, as Nagel argued, Neutralism wins. We must reject both the Self-interest Theory, and the Present-aim Theory, and most of Common-Sense Morality.' In this case, only timeless, impersonal (agent-neutral) reasons survive.
On the second horn, 'Suppose next that, as Nagel now believes, reasons can be relative. (P1) rightly claims that, if reasons can be relative, they can be relative to the agent at the time of acting.' This undercuts S’s claim that reasons must be temporally neutral.
Parfit then sketches the temporal variability of reasons: 'it could be true that I once had a reason to promote some aim, without its being true that I have this reason now' and likewise that 'I shall have a reason ... without its being true that I have this reason now.'
He infers that 'Since these could both be true, it cannot be claimed that the force of any reason extends over time.' This conclusion 'undermines the S-Theorist’s Second Reply', which assumed that reasons’ force always extends over time and thereby tried to rebut the Present-aim Theory.
Parfit notes that he is here 'discussing, not Nagel’s argument, but the Appeal to Full Relativity', which, 'Like Nagel’s argument, ... challenges the Self-interest Theory', but does so by insisting that accepting any relativity of reasons commits us to full relativity to the agent-at-a-time.

Source Quotes

Like Nagel’s argument, this appeal challenges the Self-interest Theory. One part of this appeal is (P1), the claim that, if reasons can be agent-relative, they can be fully relative: relative to the agent at the time of acting. Either reasons can be relative, or they cannot.

One part of this appeal is (P1), the claim that, if reasons can be agent-relative, they can be fully relative: relative to the agent at the time of acting. Either reasons can be relative, or they cannot. If they cannot, as Nagel argued, Neutralism wins.

Either reasons can be relative, or they cannot. If they cannot, as Nagel argued, Neutralism wins. We must reject both the Self-interest Theory, and the Present-aim Theory, and most of Common-Sense Morality. Suppose next that, as Nagel now believes, reasons can be relative.

We must reject both the Self-interest Theory, and the Present-aim Theory, and most of Common-Sense Morality. Suppose next that, as Nagel now believes, reasons can be relative. (P1) rightly claims that, if reasons can be relative, they can be relative to the agent at the time of acting.

Suppose next that, as Nagel now believes, reasons can be relative. (P1) rightly claims that, if reasons can be relative, they can be relative to the agent at the time of acting. As I shall argue in the next chapter, it could be true that I once had a reason to promote some aim, without its being true that I have this reason now.

And it could be true that I shall have a reason to promote some aim, without its being true that I have this reason now. Since these could both be true, it cannot be claimed that the force of any reason extends over time. This undermines the S-Theorist’s Second Reply.

Key Concepts

One part of this appeal is (P1), the claim that, if reasons can be agent-relative, they can be fully relative: relative to the agent at the time of acting.
Either reasons can be relative, or they cannot.
If they cannot, as Nagel argued, Neutralism wins. We must reject both the Self-interest Theory, and the Present-aim Theory, and most of Common-Sense Morality.
Suppose next that, as Nagel now believes, reasons can be relative.
(P1) rightly claims that, if reasons can be relative, they can be relative to the agent at the time of acting.
Since these could both be true, it cannot be claimed that the force of any reason extends over time. This undermines the S-Theorist’s Second Reply.

Context

Later part of Section 57, where Parfit explicitly formulates the Appeal to Full Relativity as a formal dilemma about the possibility of relative reasons, and uses it to argue that either Neutralism is correct or the Self-interest Theory’s temporal neutrality (and its Second Reply) must be abandoned.