More on the Problematic De Se
Michael Johnson
VAP HKU
De Se Cases
Suppose Ada sees herself
in the mirror, unaware
that it’s her who is in the
mirror.
She believes what she’d
express by saying “I am
pretty.”
But she also believes what
she’d express by saying
“she is not pretty.”
Useful Convention
Henceforth, I (following
Devitt) replace locutions
like:
‘so-and-so believes what
she would explicitly
express by saying “blah
blah blah”’
with: ‘so-and-so believes
*blah blah blah*’
Problematic De Se?
If (1) what I believe are propositions,
and (2) propositions are sets of possible worlds
(e.g. the proposition that it’s raining is the set of
all worlds where it’s raining),
then (3) Ada can’t consistently believe both that
*I am pretty* and that *she is not pretty*,
since the set of worlds where *I am pretty* and
the set of worlds where *she is not pretty* have
a null intersection.
Problematic De Se?
If (1) what I believe are propositions,
and (2) propositions are Russellian
(e.g. the proposition that Sue skis is the pair
<Sue, skiing>)
then (3) Ada can’t consistently believe both that
*I am pretty* and that *she is not pretty*,
since the pairs <Ada, pulchritude> and <Ada,
anti-pulchritude> have inconsistent truthconditions.
Devitt’s Solution
Deny that what we believe are propositions.
Identify the objects of beliefs with mental
representations.
Explain the difference between de se & non de
se beliefs in terms of the differing inferential
roles of the representations involved. Devitt calls
these “modes of reference” [does he???].
De Se Modes of Referring
“What about the mode of [referring of] *I*? In a
way, this singular mode seems simpler than the
others. It is a special way that *I* has of
referring to a person that is explained solely in
terms of *I*’s functional role in the very mind
containing it.” (p. 9, emphasis added)
De Se Modes of Referring
We need to posit distinct inferential roles for
Ada’s representations *I* and *she*, otherwise
she could infer *I am pretty and not pretty*
which she obviously can’t.
But once we posit these distinct roles, there
seems to remain nothing further to explain– no
need to posit different contents for the
representations.
De Se Modes of Referring
“Thoughts and the
utterances that express
them are parts of the
natural physical world.
How, then, could they be
related to entities outside
space-time? Even if they
could, how could their
being so related do any
work?” (p. 5, e.a.)
De Se Modes of Referring
The first question I think is easy to answer (see
Stalnaker, Inquiry, pp. 8-15). Numbers are outside
spacetime, but I’m related to my height in inches (a
number).
The second question I think is spot-on. Before we
saw that it was unnecessary to posit propositions
(inferential roles do the work). And now we see that
it’s insufficient to posit propositions: because it’s
not clear how they could do the work.
Lewis’s Two Gods
“Consider the case of the
two gods. They inhabit a
certain possible world,
and they know exactly
which world it is.
Therefore they know
every proposition that is
true at their world. Insofar
as knowledge is a
propositional attitude,
they are omniscient…”
Lewis’s Two Gods
“…Still I can imagine them to suffer ignorance:
neither one knows which of the two he is. They
are not exactly alike. One lives on top of the
tallest mountain and throws down manna; the
other lives on top of the coldest mountain and
throws down thunderbolts. Neither one knows
whether he lives on the tallest mountain or the
coldest mountain; nor whether he throws
manna or thunderbolts.”
De Se Exceptionalism
1. The manna god knows exactly which world
she inhabits.
2. She does not know that *I am the manna
god.*
3. Therefore, *I am the manna god* is not
solely about which world she inhabits.
4. Therefore, the de se is special and subject to
special semantic treatment.
Propositions as Properties
Lewis suggests that we replace our old notion of
propositions with properties. To believe a property
is to self-attribute it:
To believe that *I am happy*, I self-attribute
happiness.
To believe that *he is happy*, I self-attribute living
in a possible world where Michael is happy.
For Your *I*s Only
Dr. Evil is a criminal
mastermind who
constructs a base of
operations on the moon.
On the base he has built a
giant “laser” with which
he intends to destroy all
the human inhabitants of
Earth
License to Laser
The combined military
might of the nations of
the world are unable to
stop Dr. Evil’s moon laser
(shown right).
In desperation they turn
to Adam Elga, who
suggests…
You Only Live Twice
First, we create, on Earth, a molecule-formolecule duplicate of Dr. Evil’s moon base– one
that actually works and will destroy the Earth if
the red button within is pushed.
Then, we create a complete duplicate of Dr. Evil
himself and place the duplicate inside the
duplicate moon base.
Evil’s Twin
Die Another Day
Crucially, we make sure to announce to both the
real Dr. Evil and his doppelganger everything we
have just done.
Elga suggests that in this circumstance, Dr. Evil
will refrain from destroying Earth, because he
will be uncertain as to whether he is the real Dr.
Evil or instead the recently-created but
psychologically-identical double on Earth.
Dr. Not-Know
It’s consistent with this scenario that Dr. Evil
knows exactly which possible world he is in. Just
as in the gods case, he knows all about Dr. Evil
and the doppelganger, he just doesn’t know
*I am Dr. Evil* or
*I am on the moon* or
*I am not on Earth* or
*I won’t be destroyed if I push the red button.*
The Man Who Knew Too Little
But notice that there are lots of other things Dr.
Evil doesn’t know as well:
*That pencil [over there] is on the moon.*
*That landscape [out the window] is lunar.*
*That laser was built by Dr. Evil.*
*That henchman will not be destroyed if I press
this red button.*
A View to a Kill?
1. Dr. Evil knows exactly which world he
inhabits.
2. He does not know that *that landscape is a
lunar landscape.*
3. Therefore, *that landscape is a lunar
landscape* is not solely about which world
he inhabits.
4. Therefore, the de se is not special.
Propositions as Properties
Notice, for instance, that it would be wrong to
follow the Lewis/ Chisholm/ Chierchia strategy
and treat propositions as properties:
The property of living in a world where *that is
Dr. Evil’s pen* is the very same property as the
property of living in a world where *Dr. Evil’s
pen is Dr. Evil’s pen*.
Conclusions
There’s nothing special about the de se.
Devitt is right to assimilate cases of the
‘problematic’ de se to standard Frege cases and
to “solve them with syntax”– i.e. modes of
referring.
It doesn’t necessarily follow that propositions
have to go.