Propositional Attitudes

Summer 2011
Tuesday, 07/26
Propositional Attitudes
1. What exactly are the mental states that relate us to
propositions? What is a thought, a belief, a hope, a
2. How does a mental state, of whatever stripe,
manages to relate a person to a proposition? What is
it to “grasp” a proposition?
3. What explains the difference between the various
ways of entertaining propositions (e.g. believing,
hoping, desiring)?
4. Why is it that entertaining some propositions, in
certain ways, leads us to systematically (rationally,
intelligibly) entertain certain others, in certain
appropriate ways? What’s the scientific explanation
of this fact?
Propositional Attitudes
Common Sense Psychology
O, why rebuke you him that loves you so?
Lay breath so bitter on your bitter foe.
Now I but chide; but I should use thee worse,
For thou, I fear, hast given me cause to curse,
If thou hast slain Lysander in his sleep,
Being o'er shoes in blood, plunge in the deep,
And kill me too.
The sun was not so true unto the day
As he to me: would he have stolen away
From sleeping Hermia? I'll believe as soon
This whole earth may be bored and that the
May through the centre creep and so
Her brother's noontide with Antipodes.
It cannot be but thou hast murder'd him;
So should a murderer look, so dead, so grim.
Common Sense Psychology
Fodor’s Analysis:
• Hermia has reason to believe herself
beloved of Lysander.
• But if Lysander loves Hermia, then
Lysander wishes Hermia well.
• And if Lysander wishes Hermia well,
then Lysander doesn’t voluntarily
desert Hermia at night in a dark
• But Hermia was, in fact, so deserted
by Lysander.
• Therefore Lysander left involuntarily.
So it’s is plausible that Lysander has
come to harm.
Common Sense Psychology
• At whose hands? Plausibly
at Demetrius’s. For
Demetrius is Lysander’s rival
for the love of Hermia.
• Hermia believes that
Demetrius believes that a
live Lysander is an
impediment to the success
of his (Demetrius’s) wooing
of her (Hermia).
Common Sense Psychology
• Moreover, Hermia believes that
if x wants that P, and x believes
that not-P unless Q, and x
believes that x can bring it
about that Q, then x (typically)
tries to bring it about that Q.
• Additionally, Hermia believes
that, typically, people succeed
in bringing about what they try
to bring about.
• Believing all this, Hermia infers
that perhaps Demetrius has
killed Lysander.
Common Sense Psychology
• In fact, it turns out that Hermia is
• The theory Hermia implictly relies
on to make sense of what
Lysander did and what Demetrius
may have done does not take into
account nonturnal interventions
by mischievous fairies.
• Granting, however, that the
theory fails from time to time, it
is largely successful in explaining
and making predictions about
people’s behavior.
Common Sense Psychology
• Works so well it disappears.
• In California, my brother tells me that he’ll meet
me in New York in three weeks at a certain time.
• Three weeks later at that time I’m waiting for him
at the airport.
• Common sense psychology tells me how to infer
people’s intentions from the sounds they make
and how to infer people’s behavior from their
• Imagine if we could do so well with predicting the
weather! And think about how much more
complicated the causes of behavior must be
compared to the causes of the weather!
Common Sense Psychology
“If you want to know where
my physical body will be next
Thursday, mechanics—our
best science of middle-sized
objects after all, and reputed
to be pretty good in its
field—is no use to you at all.
Far the best way to find out
(usually, in practice, the only
way to find out) is: ask me!
Common Sense Psychology
• Not just a collection of truisms or platitudes, but a
sophisticated theory, in many respects similar to the
theories we have in science.
• Includes generalizations that refer to unobservable items.
• Does not appear to be a Behaviorist theory: its
generalizations don’t directly link each mental state with
behavior but specify how different states causally interact,
e.g. with preferences and beliefs, so as to lead to actions.
• E.g. Hermia doesn’t have a simple generalization that tells
her that if x is y’s rival, then x kills y. Rather, the
generalization she uses may look more like this “if x is y’s
rival, then x prefers y to suffer, all else being equal”. This, in
turn, links to behavior/action in complex ways.
Common Sense Psychology
• Fodor claims that it is (1) a Mentalist theory
(since it makes reference to mental states) and
(2) a Realist theory (since it assumes that the
mental states causally affect one another and
the world).
• Fodor argues that common-sense psychology
is practically indispensible. “We have no idea
of how to explain ourselves to ourselves
except in a vocabulary which is saturated with
[common sense] psychology…We can’t give
[it] up because we don’t know how to.
Common Sense Psychology
Fodor’s goal is to find a
scientifically respectable way to
hold on to common sense
psychology or to “vindicate” our
talk about beliefs, desires, and so
on. “Holding onto the attitudes—
vindicating commonsense
psychology—means showing how
you could have…a respectable
science [that] explicitly
acknowledges states that exhibit
the sorts of properties that
common sense attributes to the
The essence of propositional attitudes
1. They are semantically evaluable.
2. They have causal powers.
3. The implicit generalizations of commonsense
belief/desire psychology are largely true of
A scientific psychology provides means to
“vindicate” or hold on to the attitudes just in
case it postulates states (entities, events,
etc.) satisfying 1-3.
Representational Theory of Mind
A framework for understanding the propositional
attitudes, defined by these claims:
1. Propositional attitudes pick out computational relations to
internal representations.
E.g. to believe such-and-such is to have a token mental
symbol that means that such and such and that meets a
certain “job-description”.
2. Mental processes are causal processes that involve
transitions between internal representations.
E.g. a train of thoughts is a causal sequence of tokenings
of mental representations.
According to Fodor, RTM provides way to hold on to our
common sense psychology.
Language of Thought Hypothesis
Empirical thesis about the nature of thought and thinking,
not an analysis of our concepts. A way to answer the
question: How is thinking/rationality mechanically
An elaboration of RTM.
Postulates that thought and thinking take place in a
mental language.
This language consists of a system of representations that
is physically realized in the brain of thinkers and has a
combinatorial syntax (and semantics) such that operations
on representations are causally sensitive only to the
syntactic properties of representations.
Language of Thought Hypothesis
• So-called since the token mental representations
are like sentences in a language in that they have
a syntactically and semantically regimented
constituent structure.
• The mental representations that are the direct
“objects” of attitudes are structurally complex
symbols whose complexity lends itself to a
syntactic and semantic analysis.
• Useful to think of it not as a detailed proposal but
as a foundational thesis, e.g. the “Atomic

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