many false beliefs which other people cannot comprehend. We return to
this point in chapter 6, when we discuss arguments for so-called ‘wide
content’.
We shall spend no more time on variants of the argument from inter-
pretation. Realists will be more interested in arguments which impose
limits on the extent to which beliefs themselves can be irrational, rather
than on any heuristic considerations constraining the sorts of irrationality
we canascribe.
3.2 The argument from contentThe argument fromcontentis more eVective and, in our view, does impose
constraints on possible degrees of irrationality. This argument claims,
Wrstly, that what it is for an intentional state to be the intentional state that
it is, involves its having a speciWc content; and secondly, that in the case of
beliefs, the content which they have depends, in part, upon their inferential
role. TheWrst of these claims is not in dispute. The second claim is more
controversial, but since we shall recommend a (weak) form of functional-
role semantics in chapter 7, we are committed to it.
The basic thought behind the argument from content can be presented
like this. Suppose someone sincerely assents to the statement ‘P Q’. (Here
the ‘’ is intended as a dummy sign, to be taken as a target of subsequent
interpretation.) The person also comes to believe that P, but does not
assent to the statement ‘Q’ and does not believe that Q even though still
assenting to ‘P Q’. In such a case, if the thinker expressed any belief in
assenting to ‘P Q’, it cannot have been the belief thatif P then Q.A
thinker who believesPand fails to draw the inference toQ, cannot believe
if P then Q, because it isconstitutive of having such a beliefthat one should
infer the truth of the consequent from the truth of the antecedent.
A similar point can be made using Stich’s well-known example of Mrs T
(1983). This old lady was ready to say thatPresident McKinley had been
assassinated. But when asked what had become of McKinley, she was not
sure whether he was still alive or dead. The fact that she did not believe
McKinley to be dead would seem to show that she had no stable belief that
McKinley had been assassinated, rather than that she believed that, but
was no longer rational enough to grasp that he must therefore be dead
(Carruthers, 1996c). It seems appropriate to describe this case by saying
that Mrs T had suVered a loss of memory. She remembered that ‘President
McKinley was assassinated’ said something true, but she no longer remem-
bered what that truth was.
In support of the argument from content, one can oVer some persuasive
examples of ‘content-constitutive’ inferential links. But a well-known voice
114 Reasoning and irrationality