Philosophy Lecture

Philosophy 001

Lecture 2

Text: Reason and Argument, R. Feldman

Reading: Chapter 2 Truth and Rationality

Agenda:

• Truth and correspondence to the facts

• truth
• sentence tokens/types
• propositions

• Rational Belief

• belief, disbelief, and suspension of judgment
• belief and disagreement
• reasons for belief
• a principle of rational belief
• fallibilism

• Rationality, Relativity and Objectivity

Truth and Correspondence to the facts:

A declarative sentence is used to describe the world.

 It is true:

• if and only if things really are the way the sentence says they are
• if and only if the sentence describes the world correctly
• if and only if it corresponds to the facts

These are all ways of expressing the same idea.

Correspondence Principle (CP):

A declarative sentence is true just in case it corresponds to the facts as they actually are.  A declarative sentence is false just in case it fails to correspond to the facts as they are.

Note: CP does not provide a method for telling whether a sentence is true or false.

A mistaken objection to CP

Consider ‘The Sun moves around the Earth’ as written by someone in answer to an exam question in 500 BC.  

Such a person would get their answer marked ‘right’.  Should we say that it was true for them, in spite of the sentence failing to correspond to the facts as we now know them to be?

No.  It was always false.  The facts were the same in 1200, and the sentence failed to correspond to them, even though no one knew this.

A genuine problem with CP

Example (1)

Suppose I mistakenly think that this class begins at 5:30,  but you arrived at 5:45 we both say:

‘I was on time.’

Does this sentence correctly describe the world or not?  Does it correspond to the facts?  Only one of us has said something true, but we have both asserted the same sentence. One sentence cannot be both true and false.

Sentence tokens versus sentence types

• Sentence tokens are specific utterances or marks on a writing surface.
• Sentence types are types, or kinds of sentence tokens

In Example 1 there are 2 sentence tokens and 1 sentence type.

Another example of the type/token distinction: We all are using the same textbook.  But not the same token.  We are using the same text-book type.  Contrast this with the case when I lend you my copy of the textbook.  Then we are using the same token.

Propositions

A proposition is the thought or idea expressed by a sentence token.

Example 2

You and I both say: ‘Vancouver is wet in the winter but lovely in the spring.’

We have 2 sentence tokens; 1 sentence type; and 1 proposition – we both express a single thought: the thought that Vancouver is wet in winter but lovely in the spring.

But in Example 1, we have 2 sentence tokens, 1 sentence type, and 2 propositions – one expresses the thought that I was on time; the other expresses the thought that you were on time.  Only the second one correctly describes the world.

Here is another example where we have a single sentence type that can express numerous different propositions:

Example 3

John is happy.

‘John’ can refer to numerous different people named John.  In order to assess the truth value of any given token, we need to attend to the context in which it is uttered or written.

The only cases where a sentence can express more than one proposition are:

1.  Sentences containing pronouns (I you, we et.)
2. Sentences containing proper names.
3. Sentences containing words that refer to times (now, then, yesterday etc.)
4. Sentences containing words that refer to places (here, there, in THIS room etc.)
5. Demonstratives

Amended CP (CP2)

A proposition is true just in case it describes things as they actually are.  A true proposition corresponds to the facts.  If a proposition says that a certain object has a particular characteristic, then it is true just in case that object actually does have that characteristic.  A proposition is false just in case it fails to describe things as they actually are.  A false proposition does not correspond to the facts.  If a proposition says that a certain object has a particular characteristic, then it is false if that object does not have that characteristic.