FREGEAN SEMANTICS
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REFERENCE (Bedeutung)
├── What expression picks out
├── "Venus" refers to Venus
└── Compositional: Reference of whole from parts

SENSE (Sinn)
├── Mode of presentation
├── Cognitive significance
├── "Morning star" vs. "Evening star"
└── Same reference, different sense

WHY BOTH?
├── "Hesperus = Phosphorus" is informative
├── "Hesperus = Hesperus" is trivial
├── Same reference, different sense
└── Sense determines reference

"The F is G" =
∃x(Fx ∧ ∀y(Fy → y=x) ∧ Gx)

"There is exactly one F, and it is G"

Not a referring expression but a quantified claim
False (not meaningless) because no unique F exists

KRIPKE'S ARGUMENTS
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MODAL ARGUMENT:
"Aristotle might not have been a philosopher"
├── Makes sense
├── But "The teacher of Alexander might not have taught Alexander"
│   └── Would make Aristotle not Aristotle
└── Names ≠ descriptions

EPISTEMIC ARGUMENT:
We can discover "Hesperus = Phosphorus"
├── A posteriori necessary truth
├── Same thing in all worlds
└── But discovered, not known a priori

SEMANTIC ARGUMENT:
Reference is causal-historical
├── Not by fitting description
├── Baptism + chain of communication
└── Name-using practice

SPEECH ACT THEORY
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THREE TYPES OF ACTS:

LOCUTIONARY
├── Saying something with meaning
└── Uttering words with sense and reference

ILLOCUTIONARY
├── What you do in saying it
├── Promising, warning, asserting
└── Force of the utterance

PERLOCUTIONARY
├── Effect on hearer
├── Persuading, frightening, amusing
└── Consequences of saying

FELICITY CONDITIONS:
├── Preparatory: Appropriate circumstances
├── Sincerity: Speaker means it
├── Essential: Counts as the act
└── Infelicity: Act fails (not false, but unhappy)

TWIN EARTH
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Scenario:
├── Twin Earth exactly like Earth
├── Except "water" is XYZ, not H₂O
├── XYZ phenomenally identical to H₂O
└── 1750: No one knows difference

Question: Does "water" mean the same?

Putnam: No!
├── "Water" on Earth refers to H₂O
├── "Water" on Twin Earth refers to XYZ
├── "Meanings ain't in the head"
└── Natural kind terms refer to natural kinds

TARSKIAN TRUTH
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T-SCHEMA:
"S" is true iff S

EXAMPLE:
"Snow is white" is true iff snow is white

Requirements:
├── Object language (mentioned)
├── Metalanguage (used)
├── Hierarchy avoids liar paradox
└── Truth defined for formal languages

KAPLAN'S THEORY
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CHARACTER
├── Rule for determining reference
├── "I" = speaker of context
└── Constant across contexts

CONTENT
├── What's said in context
├── "I am tired" said by me
└── Proposition about me