Re: All panduks are green

On Apr 10, 3:30 am, stevendaryl3...@xxxxxxxxx (Daryl McCullough)
wrote:
Newberry says...

If you want to argue that one horn is not the essence of unicorness,
and therefore "all unicorns have two horns" is not analytic, that's
fine. But it still does not make the sentence true.

Whoa, Nellie! How is it not true? It is meaningful, right? And
hence has a truth value, right?

No. Meaningless statements are a proper subset of statements that do
not have a truth value.

Look, we know perfectly well the conditions under which "all Xs are Ys"
can be assigned a truth value true or false. If there is some object
that is X but is not a Y, then the sentence "all Xs are Ys" is true.
Otherwise, it is false.

What is the *point* of calling it meaningless? What is the *point*
of saying it has no truth value, when we have a perfectly good
way to assign it a truth value?

This is a very good question and I will give you a very good answer.

1. We need a sensible definition of truth. "A sentence is true iff it
corresponds to an existing state of affairs" is a sensible definition.
Similarly "a sentence is meaningful iff it is a picture of a possible
state of affairs" is a sensible definition. Accordingly we have "all
round squares are green" is meaningless because it is not a picture of
a possible state of affairs. "All unicorns are green" is meaningful
because it is a picture of a possible state of affairs. It is not true
because the state of affairs, which the sentence is a picture of does
not exist. "all unicorns are NOT green" is not true either.

2. I could turn the question around and ask why we need to assign a
truth value if we do not have to? What is the tradeoff? There is one
advantage in not assigning a truth value to the so called "vacuously
true" sentences - most logic puzzles will disappear. If we decide to
treat the "vacuously true" propositions as neither true nor false then

(x)(x # x --> x > x)

does not have a truth value because ~(Ex)(x # x). Analogically, if

~(Ex)Pxm

then

~(Ex)(Ey)(Pxy & Qy)

does not have a truth value, if Q is satisfied only by y = m. Do I
need to go any further in describing what P and m might be?






.

Relevant Pages

  • Re: The truth of evolution
    ... state of affairs. ... Rorty doesn't believe there is any absolute truth. ... Rorty's a pragmatist so I doubt he would adopt the fairy shoe ... increases the sum of happiness. ...
    (uk.philosophy.humanism)
  • Re: Gallup Poll: Two-thirds of US Are Creationists [Atheists Lose, Again]
    ... Its a sad state of affairs when the Lack of "truth and knowledge" ... provide the environment for myth. ...
    (alt.politics)
  • Re: All panduks are green
    ... of saying it has no truth value, when we have a perfectly good ... Similarly "a sentence is meaningful iff it is a picture ... of a possible state of affairs" is a sensible definition. ... unicorns are NOT green" is not true either. ...
    (sci.logic)
  • Re: Skolem Again
    ... >> such trouble distinguishing truth from truth in a model. ... states of affairs in model theory *at all*. ...
    (sci.logic)
  • Re: All panduks are green
    ... corresponds to an existing state of affairs" is a sensible definition. ... truth value if we do not have to? ... is meaningless when there are no Xs. ...
    (sci.logic)