 (Valerie Walker (1990) and Stephen Stich (1991) propose that narrow contents could be expressed if English were supplemented with a “bracketing” notation. For example, an expression of the form ‘___ has the (narrow) content that [p]’ is said to have as its extension “in any possible world the class of brain state tokens whose (broad) content is p, along with physically identical tokens in all doppelgangers of people who harbor tokens whose broad content is p” (Stich 1991, p. 247). The chief difficulty with this proposal is that it has the consequence that every token with a given broad content has the same narrow content. But mental states with a particular broad content can be very unlike one another: compare Oscar’s belief that water is wet with that of an expert in chemistry, or the very different ways in which Pierre is related to the proposition that London is pretty. If narrow content is to be useful in explaining behavior and rational inference, it must be the case not only that Twins share their narrow contents despite their different broad contents, but also that individuals with the same broad content may have different narrow contents (Brown 1993).)