1. No new reading for Tuesday. We’ll continue talking about Segal’s paper.
Intension v. extension (sense v. reference):
The extension of a term (or concept) is the collection of things to which the terms applies; the extension conditions of a term t summarize what the things in t’s extension all have in common and what condition needs to be satisfied in order for something to be in t’s extension.
Intension: the general idea or concept (typically expressed in the form of a definition or description) that a term expresses; on a standard view, this determines the extension of a term.

2. On this way of putting things, it looks as if the extension conditions and the intension are the same thing. BUT, content/semantic externalism can break this connection. Content externalism/semantic externalism, as it’s normally construed: Something beyond the speaker’s psychological states/physical body determines extension conditions (speakers’ intensions do not always suffice to determine the extension of her terms).

3. Why Believe Externalism?
Putnam’s Twin-Earth Case: Twin-Earth appears to be just like Earth but has mystery compound XYZ in place of H2O. Earthling Oscar says, “Water is wet.” His physical duplicate on Twin-Earth says “Water is wet.” Their statements have different truth-conditions (one is talking about H2O, the other about XYZ). Therefore, the extension conditions of ‘water’ are determined by external factors. Putnam says that you can hold on to the standard view of intensions (as determining extensions) only if you’re willing to say that we don’t grasp intensions.

4. Burge’s Social Externalism
Extensions can be fixed socially, by the practices of, or intensions employed by, experts. He holds on to the idea that intension (i.e., cognitive content) determines extension, partly because he wants to hold on to the Fregean view that intensions are expressed by the words in a public language.

5. Burge on Propositional Attitude Ascription
Propositional attitude ascriptions track cognitive content.
Cognitive content determines extension conditions.
Extension conditions are determined partly by the broader social context; that is, they are partly a function of factors beyond (the relevant bits of) the psychology of the individual thinker.
Therefore, cognitive content is partly a function of external factors.