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Theories of Truth
Truth
To say of what is that it is not, or
of what is not that it is, is falsity.
To say of what is that it is, or of
what is not that it is not, is truth.
Truth and Action
True beliefs lead to successful actions.
Truth and Action
Suppose:
You desire to hang out with your friends for another hour.
You desire to deposit your paycheck in the bank.
You prefer to deposit your check to hanging out with your friends.
You believe the bank closes at 6pm.
You believe that if you hang out with your friends for another hour, you
can still deposit your check.
Plan: hang out, then go to the bank.
Truth and Action
True belief case:
You get to hang out and deposit your check.
False belief case:
Your greatest desire (deposit check) is unsatisfied.
The Aim of Belief
One view of what belief is, is that
belief is the mental state that
‘aims at’ truth.
Knowledge and Truth
A mental state is factive if you can only be in that state when the
content of that state is true.
Knowledge is factive: If you know that p, then p must be true.
Grice’s Maxims
Quality: Try to make your
contribution one that is true.
Quantity: Make your contribution
as informative as is required (for
the current purposes of the
exchange); Do not make your
contribution more informative
than is required.
Grice’s Maxims
Relation: Be relevant.
Manner: Be perspicuous.
Flouting
The form of a flouting inference is something like this:
“The speaker is openly failing to fulfill such-and-such maxim, though I
have strong reason to think the speaker wants the purpose of the
conversation to succeed. The only good reason to be uncooperative,
given that, would be if q. So the speaker must want me to believe q.”
Flouting Quality
One typically flouts the maxims of quality when one engages in irony,
metaphor, understatement, and hyperbole.
For example: The speaker said “Dick Cheney is a monster”; but he can’t
really believe that Cheney is a monster, because monsters don’t exist;
he must really mean that Cheney is a terrible person.
Why We Are So Clever
“[A] creature that knows what
would make its thoughts true and
what would cause it to have them,
would be in a highly advantageous
epistemic position:…”
Why We Are So Clever
“It would be able, with premeditation, to cause itself to have true
thoughts. In particular, to construct, with malice aforethought,
situations in which it will be caused to have the thought that P if and
only if the thought that P is true.”
Why We Are So Clever
“I think it's likely that we are the
only creatures that can think
about the contents of our
thoughts.”
Background
Criteria vs. Definitions
A definition of ‘true’ gives the meaning of the word ‘true.’
A criterion for truth gives us a means of telling whether something is
true.
Some “theories of truth” are better thought of as giving criteria rather
than giving truth-definitions.
The Bearers of Truth
What sorts of things can be true?
Sentence types?
Sentence tokens? (utterances)
Propositions?
Types vs. Tokens
Worries about Propositions
1. General issues with abstracta
2. A new kind of “going together” (unity of the proposition)
The Correspondence Theory
The Correspondence Theory
A correspondence theory of truth
views sentences/ propositions
that are true as ones that
“correspond” with the facts.
Truth the goddess is often
depicted holding a mirror: truth
mirrors the way the world is.
Logical Atomism
For (early) Wittgenstein and
(atomism-period) Russell, the
world was composed of objects,
properties, and relations “going
together”.
The Facts
For example, one fact might be an
object, Michael, another object,
this particular hat, and the
relation of wearing.
These objects and relation “go
together” to make a fact.
Correspondence
Truth then is a correlation between sentences/ propositions and the
facts that make them true.
“Michael is wearing a hat”
“Grass is green”
“Goats wear glasses”
The Facts
Problem: which objects and
properties going together
constituted the fact that Michael
is not wearing a blue shirt?
We need this fact to correspond
to the sentence “Michael is not
wearing a blue shirt.”
Compositional Analysis
Maybe the correspondence theory should be applied to the atomic
sentences, and more complex sentences have their truth-conditions
determined by the truth-conditions of their atomic parts:
“NOT: P” is true iff P is not true (does not correspond with the facts).
The Facts
“Michael is wearing a blue shirt.”
So: “Michael is not wearing a blue
shirt” is true.
Does not correspond
The Coherence Theory
Neurath’s Raft
What Is Coherence?
• Can’t be satisfiability!
• Not mere consistency
• Comprehensiveness
• Truth-likeness
• Criterion or definition?
The Pragmatist Theory
William James
• 1842-1910
• American philosopher/
psychologist
Charles Sanders Peirce
• 1839-1914
• American philosopher/ logician/
mathematician/ chemist
• Along with Frege, independently
discovered modern logic
John Dewey
• 1859-1952
• American philosopher/
psychologist/ education
reformer
• Advocate of democracy and
education
Pragmatism
“There can be no difference that
makes no difference.”
Peirce’s Pragmatism
Correct definition of truth:
correspondence with reality.
Way to tell whether something is
true: use science.
Criterion for truth: what we
believe ‘at the end of inquiry’.
Primitivism, Redundancy,
Delfationism
Perennial Options
In philosophy, two options are always available: primitivism and
deflationism.
Primitivism
The primitivist theory says that
truth is a primitive… there’s
nothing more to say.
Some Equivalences
“Snow is white” is true ↔ Snow is white
“Snow is purple” is true ↔ Snow is purple
“Michael is a philosopher” is true ↔ Michael is a philosopher
“Michael is a shark” is true ↔ Michael is a shark
And so on…
Frank P. Ramsey
• 1903-1930
• Died at 26
• Influential philosopher/
economist/ mathematician
• Created a branch of
mathematics ‘Ramsey Theory’
• Good friend of Wittgenstein
The Redundancy Theory of Truth
Ramsey’s view of truth was that
‘it’s true that p’ is just a fancy way
of saying p.
‘Is true’ is redundant. We don’t
need to say it, but we can if we
have extra time on our hands.
Virtue of Redundancy
Saying something ‘is true’ is not saying anything in addition to just
saying that thing.
So the question of ‘what are the bearers of (the property of) truth?’
goes away: there is no property.
Problems for Redundancy
Consider the sentence ‘what Michael said is true.’ Try to say this
without ‘is true’.
Attempt: Michael said ‘poodles like noodles’ and poodles like noodles;
OR Michael said ‘lemurs have femurs’ and lemurs hate femurs; OR
Michael said ‘llamas star in dramas’ and llamas star in dramas; OR….
Problems for Redundancy
Consider the sentence ‘everything Michael said is true.’ Try to say this
without ‘is true’.
Attempt: If Michael said ‘poodles like noodles’ then poodles like
noodles; AND If Michael said ‘lemurs have femurs’ then lemurs hate
femurs; AND If Michael said ‘llamas star in dramas’ then llamas star in
dramas; AND….
Problems for Redundancy
Consider the English sentence “‘Der Schnee ist weiss’ is true” Try to say
this in English without ‘is true’.
Attempt: If ‘Der Schnee ist weiss’ translates to ‘poodles like noodles’
then poodles like noodles; AND If ‘Der Schnee ist weiss’ translates to
‘lemurs have femurs’ then lemurs hate femurs; AND If ‘Der Schnee ist
weiss’ translates to ‘llamas star in dramas’ then llamas star in dramas;
AND….
Deflationism
The deflationist theory of truth
says that truth is not redundant,
but that ‘is true’ is simply an
expressive device.
You could have a language with no
‘is true’ that could say everything
English can say.
Infinitary Conjunction and Disjunction
Everything Michael says is true:
&{ p | if Michael says “p”, then p }
That one thing Michael said is true:
v{ p | Michael said “p” and p }
Problems for Deflationism
We began with the observation that true beliefs lead to successful
actions.
Why should this be so if ‘is true’ is a dispensable expressive device.