Metaphysics & Ontology Skill

Master the fundamental questions of metaphysics: What exists? What is being? What is the ultimate nature of reality?

Core Questions

Fundamental Issues

Question	Field	Examples
What exists?	Ontology	Numbers? Properties? Possible worlds?
What is being?	Fundamental ontology	Being vs. beings
What are things made of?	Substance metaphysics	Matter, form, properties
What makes something the same over time?	Persistence	Personal identity, ship of Theseus
What is causation?	Causal metaphysics	Regularity, counterfactual, powers
What is possible/necessary?	Modality	Possible worlds, essence

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Ontology: What Exists?

Ontological Categories

ONTOLOGICAL LANDSCAPE
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CONCRETE PARTICULARS
├── Physical objects (tables, planets)
├── Mental events (thoughts, pains)
└── Persons

ABSTRACT OBJECTS (?)
├── Numbers, sets
├── Propositions
├── Properties/universals
└── Possible worlds

EVENTS AND PROCESSES
├── The Battle of Waterloo
├── The melting of ice
└── My walking to work

FACTS AND STATES OF AFFAIRS
├── That snow is white
├── The redness of the apple
└── The table's being square

Platonism vs. Nominalism

Platonism: Abstract objects exist

• Numbers exist independently of minds
• Properties are real universals
• Mathematical truth is discovery, not invention

Nominalism: Only particulars exist

• No abstract objects
• "Redness" is just a word for similar things
• Mathematical objects are useful fictions

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Substance and Properties

Substance Theories

Aristotelian Substance:

• Primary substances: individual things (this horse)
• Secondary substances: kinds (horse, animal)
• Substances persist through change; accidents don't

Bundle Theory:

• No underlying substance
• Objects = bundles of properties
• Problem: What ties the bundle together?

Substratum Theory:

• Bare particulars underlie properties
• Problem: What is bare substratum? Unknowable?

Properties

Universals vs. Tropes:

Universals	Tropes
One property, many instances	Each instance a particular
"Redness" is one thing	This red ≠ that red
Shared by objects	Resembling particulars
Explains resemblance	Avoids mysterious sharing

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Identity and Persistence

Personal Identity

Theories:

PERSONAL IDENTITY THEORIES
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PSYCHOLOGICAL CONTINUITY
├── Memory, personality, beliefs
├── Locke: consciousness makes identity
├── Parfit: What matters isn't identity
└── Problems: Fission, amnesia

BIOLOGICAL CONTINUITY
├── Same organism = same person
├── Animalism (Olson)
└── Problems: Transplant cases

SOUL/SUBSTANCE VIEW
├── Immaterial soul persists
├── Problems: Interaction, detection
└── Forensic vs. metaphysical identity

Ship of Theseus

SHIP OF THESEUS
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Original ship's planks gradually replaced.
Is it still the same ship?

VARIANT: Old planks reassembled into second ship.
Which is the original?

POSITIONS:
├── Neither (no real identity)
├── Repaired ship (spatial continuity)
├── Reassembled ship (material continuity)
└── Both partially (graded identity)

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Causation

Theories

Regularity Theory (Hume):

• Causation = constant conjunction
• No necessary connection
• "Cement of the universe" is just habit

Counterfactual Theory (Lewis):

• C causes E iff: If C hadn't occurred, E wouldn't have
• Analyzed via possible worlds

Powers/Dispositions:

• Causes have intrinsic causal powers
• Salt's solubility is real property
• Not reducible to regularities

Process/Mechanism:

• Causation = physical process
• Transfer of energy, momentum
• Tracing causal history

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Modality

Possible Worlds

Modal Claims:

• Necessarily P: P is true in all possible worlds
• Possibly P: P is true in some possible world
• Contingently P: P is true but could be false

What Are Possible Worlds?:

POSSIBLE WORLDS REALISM
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MODAL REALISM (Lewis)
├── Possible worlds are concrete realities
├── As real as actual world
├── "Actual" is indexical (like "here")
└── Controversial but powerful

ERSATZISM
├── Possible worlds are abstract objects
├── Sets of propositions, or
├── Maximal states of affairs
└── More conservative

FICTIONALISM
├── Possible worlds are useful fictions
├── No commitment to existence
└── Instrumentalist reading

Essence and Necessity

Essential Properties: Properties a thing must have to be that thing Accidental Properties: Properties a thing happens to have

Kripkean Essentialism:

• Origin is essential (you couldn't have different parents)
• Natural kinds have essences (water = H₂O necessarily)
• Names are rigid designators

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Time

Theories of Time

A-Theory (Tensed):

• Past, present, future are real
• Present is metaphysically special
• Time flows

B-Theory (Tenseless):

• Only earlier-than, simultaneous, later-than relations
• No privileged present
• "Block universe" — all times equally real

Persistence Through Time

Endurantism: Objects are wholly present at each moment Perdurantism: Objects have temporal parts (stages)

PERSISTENCE VIEWS
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ENDURANTISM               PERDURANTISM
├── Object wholly         ├── Object has temporal parts
│   present at each time  │   (like spatial parts)
├── Properties change     ├── Different stages have
│   (intrinsic change)    │   different properties
└── Intuitive but         └── Handles change better but
    faces puzzles             counterintuitive

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Composition

The Special Composition Question

When do parts compose a whole?

Universalism: Any objects compose something Nihilism: No composite objects exist Restricted: Some conditions required (contact, life, etc.)

Mereology

• Part-whole relations
• Proper vs. improper parts
• Transitivity of parthood
• Supplementation principles

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Key Vocabulary

Term	Meaning
Ontology	Study of what exists
Metaphysics	Study of fundamental nature of reality
Substance	What exists in itself
Property	What is attributed to substance
Universal	One thing shared by many
Particular	Individual, unrepeatable
Trope	Particular instance of property
Modal	Concerning possibility/necessity
A priori	Independent of experience
A posteriori	Dependent on experience
Essence	What makes thing what it is
Accident	What thing contingently has
Supervenience	No A-difference without B-difference
Haecceity	Thisness; individual essence

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Integration with Repository

Related Themes

• thoughts/existence/: Being, reality, metaphysics

Thought Experiments

• Ship of Theseus
• Teletransporter
• Twin Earth (for natural kinds)