On Sense and Nominatum / On Sense and Reference

Key Question: What is the meaning of a NAME?

 

 

 

1. Sentence

  • Sentences are capable of being TRUE or False

    These are sentences

    1. Earth is round
    2. Bob Dylan is a songwriter

    These are NOT sentences

    1. Shut that door!
    2. Ouch!
    3. Who are you?

  • Sentence's Truth & Falsity depend on

    1. MEANING = What the sentence means
    2. REALITY = How things really are

    A sentence represents reality in a way, reality is (or is not) that way

    Bob Dylan is a songwriter - TRUE

    James Walsh is a songwriter - FALSE

    Names refer to different MEANINGs. If the names differ in their referent, they make different contributions to the TRUTH-VALUE of the sentence

    [ A Simple Test ] Take two names refer to the same person and test if the meaning of the sentence changes

    Bob Dylan is from Minnesota, his real name is Robert Zimmerman

    1. Bob Dylan is a songwriter

    Robert Zimmerman is a songwriter

    1. Bob Dylan is from Texas

    Robert Zimmerman is from Texas

    Example [1] = both TRUE

    Example [2] = both FALSE

    Meanings are coherent

  • Logically valid conclusions follows just the meaning of the sentences

    Two ways of reasoning

    • Method 1

      1. Socrates is a man
      2. All men are mortal
      3. Socrates is mortal

    • Method 2

      1. Bob Dylan is a great songwriter
      2. Bob Dylan is from Minnesota what if we replace "Bob Dylan" with "Robert Zimmerman"?
      3. A great songwriter is from Minnesota

    Frege thinks you should reason in Method 1

 

 

 

2. Name

  • Every Name has

    1. Nominatum

      what the name picks out, relevant to Truth & Falsity

    2. Sense

      the mode of presentation of the Nominatum, relevant to cognitive matters (ex. logic, inference)

    Examples

    1. Frege's Favorite Example

      Therefore, the Nominatum of Phosphorus & Hesperus is Venus

      • Hesperus = Hesperus - TRUE, Cognitively Trivial
      • Hesperus = Phosphorus - TRUE, Cognitively Significant

    2. What is the Sense of a Name?

      If you watch the Moon with a telescope

      • Moon = Nominatum
      • The Moon on the glass = Sense
      • People have different private impression ("Image") while watching the Moon on the glass

    Frege thinks that

    1. Sense is NOT an image in your head
    2. Images vary from person to person
    3. Communication requires a shared Sense

  • Sense determines Nominatum

    Two Names share Sense, then they share Nominatum

    Two Names with same Nominatum can have different Senses

  • The Nominatum of a Sentence is its Truth-Value

    Sentences with same Nominatum but different Senses

    1. Nominatum = Truth

      The Earth is round

    2. Nominatum = Falsity

      The Earth is flat

  • Truth-Value of a sentence contributes to that of a bigger Sentence

    1. - TRUE
    2. The sky is blue - TRUE
    3. [1] and [2]

    replace [1] with "The Earth is round", then [3] is still TRUE

    replace [1] with "", then [3] is FALSE

  • Truth-Valueless Sentence

    • it is meaningful
    • it has Senses
    • but "Ulysses" does not have a Nominatum
    • so it is neither TRUE nor FALSE, it is truth-valueless