In 1750, Oscar on Earth and Twin-Oscar on Twin Earth are in exactly the same internal psychological states when they use the word 'water.' According to Putnam's externalism, what follows?
ATheir words refer to the same substance, since meaning is determined by internal states
BTheir words mean different things: Oscar's 'water' refers to H2O, Twin-Oscar's to XYZ
CNeither can know what their word means until molecular chemistry is discovered
DThey share both narrow and broad content, since the observable properties are identical
Putnam's key conclusion is that identical internal states do not guarantee identical meaning. Oscar's 'water' refers to H2O because that is what fills the oceans and lakes in his environment; Twin-Oscar's refers to XYZ for the same reason in his. Their broad content (actual referent) differs even though their narrow content (inferential role, observable associations) is the same. This is the central move of externalism: 'meanings just ain't in the head.'
Question 2 Multiple Choice
What is the primary distinction between broad content and narrow content in the externalist framework?
ABroad content is conscious; narrow content is unconscious
BBroad content is fixed by the external environment and determines truth conditions; narrow content is determined by internal inferential role alone
CBroad content applies to natural kind terms; narrow content applies only to names
DBroad content is what a speaker intends; narrow content is what listeners understand
Broad (wide) content is externally constituted — it tracks the actual referent in the world, fixed by the speaker's causal-historical connection to their environment. It determines the truth conditions of beliefs and utterances. Narrow content is whatever can be determined from internal states alone — the conceptual role a term plays, its inferential connections to other mental states. Oscar and Twin-Oscar share narrow content for 'water' (same inferential role) but differ in broad content (different substances referred to). Externalism claims the philosophically significant notion — the one that fixes truth conditions — is broad.
Question 3 True / False
According to externalism, two people with identical internal brain states can hold beliefs with different truth conditions.
TTrue
FFalse
Answer: True
This is the core claim of externalism, illustrated by the Twin Earth case. Oscar believes 'water is drinkable' and Twin-Oscar believes 'water is drinkable,' but their beliefs have different truth conditions: Oscar's is true iff H2O is drinkable; Twin-Oscar's is true iff XYZ is drinkable. The environmental differences — not any difference in internal states — account for the difference in content. Externalism thus breaks the assumption that mental content supervenes solely on internal physical states.
Question 4 True / False
Externalism about mental content implies that people can seldom have privileged access to their own thoughts, since they may not know what their words actually refer to.
TTrue
FFalse
Answer: False
Externalists typically defend compatibility between externalism and privileged self-knowledge. Oscar knows he is thinking about water — he has direct access to the fact of his thought. He may not know the molecular structure of water (H2O), but that is knowledge about chemistry, not knowledge about his own mental state. The externalist separates knowing *that* you are thinking about water from knowing the complete nature of water's microstructure. Privileged access concerns the former; externalism concerns the latter. The two do not conflict.
Question 5 Short Answer
Why does the Twin Earth thought experiment challenge the internalist view that 'meaning is in the head'?
Think about your answer, then reveal below.
Model answer: Internalism holds that the content of a word or thought is fully determined by the speaker's internal mental states. Twin Earth refutes this: Oscar and Twin-Oscar have identical internal states in 1750 yet their uses of 'water' refer to chemically different substances (H2O vs XYZ). If content were purely internal, their words would mean the same thing. Since they refer to different substances, something external — the actual substance in their respective environments — must be part of what fixes meaning. The environment is partly constitutive of content, not merely a context in which pre-formed internal meanings get expressed.
The thought experiment's force comes from holding internal states constant while varying the external environment. Any difference in content must then be traced to the environmental difference. This isolates the external contribution to meaning and shows it is ineliminable. The implication for psychology and philosophy of mind is significant: intentional mental states are not purely internal phenomena — they essentially involve the world the agent is embedded in.