Narrow narrow content Narrow content is whatever is shared by physical duplicates. It is a function (in the mathematical sense) from environments to broad contents. It’s thought to be necessary to play a local, causal role in the production of behavior.

Sawyer’s objections -It’s not content (functions aren’t representational). -It’s derivative upon broad content; it’s just whatever gets added to a context to produce a broad content. -It’s not necessary for an explanatory psychology (mechanisms might be necessary to implement psychological laws, but psychological laws aren’t about local mechanisms).

Epistemic narrow content Something like the subject’s first- person perspective or the evidence that the subject has direct access to. For all subjects knew in 1600, water could have turned out to be H2O or XYZ. Sawyer: What form does such evidence take? Is there a sufficiently rich, neutral language in which it can be stated or conceived of?

Thoroughly narrow content On this view, all psychological content is narrow. True propositional attitude ascriptions assert a (sufficiently close) match between the sense of the expression used to attribute the attitude and the content of the attitude.

Sawyer’s objections If content is to play a role in psychological explanation, it must be shared by different subjects. On Segal’s view, there is too much variation in individual narrow content for there to be any viable scientific (or explanatory) psychology.

The McKinsey Problem 1. I can know a priori the contents of my beliefs, for example, my belief that water is wet. 2. My thinking that water is wet conceptually implies that H2O exists. (This is entailed by externalism, so long as we take for granted what we think we know now about chemistry.) 3. That H2O exists can be known only a posteriori.

What’s the problem? If I know that I’m thinking that water is wet, and I know by conceptual necessity that externalism is true, then I should be able to know a priori that H2O exists (whether one appeals to CAK or CA). This contradicts (3). At least one of the 3 claims must be rejected.

Brueckner’s Response Externalism does not entail that (2) can be known a priori; even if we can know a priori that externalism is true, this does not yield a priori knowledge of the specific external conditions necessary for us to have thoughts with the relevant contents. It’s merely metaphysically necessary that H2O exists if I’m thinking that water is wet (AND if water is, in fact, H2O); it’s not conceptually entailed by my being in that state alone, even if we know externalism a priori.

Kinds of Necessity Nomological (or physical) necessity: what could not be false given the laws of nature (e.g., if it is a law of nature that nothing can move faster than c, then it is nomologically necessary that nothing moves faster than c). Logical necessity: A claim is logically necessary if and only if its negation entails a contradiction in an adequate system of formal logic (perhaps allowing the substitution of synonyms for synonyms). For example, all bachelors are male.

Kinds of Necessity, 2 Logical necessities are often associated with what can be known a priori (what can be known by consideration of the relevant concepts alone), and (distinctively) nomological necessities are associated with what can be known only a posteriori. Metaphysical necessity falls in between. It includes things that couldn’t possibly be otherwise, but which would not yield a contradiction when negated (even when allowing substitution of synonyms for synonyms) – for instance, that water is H2O. These are often called ‘a posteriori necessities’.