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Work #922 · Late (Parfit's final, three-decade-in-the-making work — his second after Reasons and Persons, 1984)

On What Matters

Derek Parfit
2011 (Vols I & II, Oxford UP); 2017 (Vol III, Oxford UP — published months after Parfit's death) · English
Three-volume philosophical treatise · Twenty-first-century analytic ethics / moral realism

Kantian ethics, contractualism, and rule-consequentialism climb the same mountain from different sides — and what we ought to do is independently real

Attribute Fingerprint

Rows where works disagree are highlighted in gold. The full ontology grid is shown.

Attribute On What Matters (Late (Parfit's final, three-decade-in-the-making work — his second after Reasons and Persons, 1984))
Time · Extent Infinite
Time · Ontological Status Substantival
Time · Grain Continuous
Time · Freedom Non-Deterministic
Time · Traversability Linear
Time · Dimensionality One
Time · Direction Uni-directional
Space · Extent Infinite
Space · Ontological Status Substantival
Space · Curvature Flat
Space · Dimensionality Three
Space · Locality Local
Matter · Extent Infinite
Matter · Ontological Status Substantival
Matter · Conservation Conserved
Matter · Dimensionality Three
Matter · Locality Local
Observer · Time Instance Single
Observer · Space Instance Single
Observer · Knowledge Extent Partial
Observer · Knowledge Retainment Total
Observer · Physicality Embodied
Observer · Agency Active
Observer · Number Plural
Observer · Metaphysical Agency None
Observer · Moral Authority Reason
Observer · Theological Method
Energy · Extent Infinite
Energy · Ontological Status Substantival
Energy · Conservation Conserved
Energy · Dispersibility Irreversible
Information · Ontological Status Substantival
Information · Cosmic Conservation Conserved
Information · Personal Conservation Conserved
Information · Granularity Continuous

Dimension-by-Dimension Evidence

What each work's passages reveal about its stance on each of the six dimensions.

Time

On What Matters

The temporal sweep — twenty-seven years between Reasons and Persons and On What Matters, three decades of revision behind the published trilogy.

Space

On What Matters

The space of analytic ethics — Oxford, Harvard, the Philosophy and Public Affairs community whose objections shape Volume III.

Matter

On What Matters

The biological-historical human agent whose moral life is the topic; Parfit's austere physicalism about the agent is inherited from Reasons and Persons.

Observer

On What Matters

The morally serious agent whose reasoning Parfit's philosophy aims to support; the philosopher who attends to where the great traditions actually meet.

Energy

On What Matters

The energies of careful argument — the book's thousands of pages of close engagement with objections.

Information

On What Matters

Normative truths as irreducible information — facts about what we ought to do that are not reducible to facts about what we want or what causes us to do things.

Internal Tensions

Where each work's argument pulls against itself.

On What Matters

The Triple Theory's convergence claim is contested at every level: Wood and Herman argue the Kantian peak Parfit reaches is not Kant's; Hooker accepts the rule-consequentialist peak; Scanlon partially accepts the contractualist peak but resists the convergence. The metaethical defense of non-naturalistic realism has won fewer adherents than Parfit hoped (Schroeder, Street, Enoch all wrote against it). Volume III's extensive replies remain incomplete on some issues — Parfit died before completing his planned response to climate-justice critics. The work's influence is more diffuse than Reasons and Persons but its place in twenty-first-century ethics is established.