“the Twin Earth Wars”
“At the start of the first act (a long time ago, around 1970) the internalist empire slumbers in dogmatic confidence that the meanings of our words and the contents of our thoughts depend only on what is in the head”
“In the first act the externalist rebels Hilary Putnam and Tyler Burge deploy Twin Earth thought experiments to argue that meaning and content often depend on matters outside the head”
“The rebels succeed so well that at this point the externalists become the empire”
“In the second act, internalist rebels strike back: David Lewis, Frank Jackson, and others argue that even in light of Twin Earth, there is a kind of narrow content that depends on what is inside the head alone”
“In this third act, the next-generation externalists Juhani Yli-Vakkuri and John Hawthorne aim to strike down internalists on behalf of the empire once and for all, deploying the awesome weapon Mirror Man to give an argument that narrow content is impossible”
“I think the argument has less bearing on issues between internalism and externalism than the authors suggest”
“To recap the history a bit more slowly: Putnam famously asked us to consider Twin Earth, which is just like Earth except that H2O is replaced by the superficially identical substance XYZ”
“Putnam argued that where we use the term ‘water’ to refer to H2O, our near-duplicates on Twin Earth use their term ‘water’ to refer to XYZ”
“Most philosophers were convinced by Putnam and Burge that at least many aspects of meaning and content are not in the head”
“Still, a minority argued that there remains a kind of content that is internal, depending on what is in the head alone. Various accounts of narrow content were put forward by Jerry Fodor, Valerie Hardcastle, Brian Loar, Joseph Mendola, Gabriel Segal, Stephen White, and others”