John, (01)
You want to distinguish between true statements and "truthlike"
statements and argue forcefully against the idea of degrees of truth.
You assign truth-values (not "truthlikeness-values" or degrees of
truth) to vague statements. For example, you say it is true that the
sun is about 93 million miles from the Earth. (02)
What exactly does that mean? (03)
In the decision analysis literature, there is the idea of the
"clarity test." Probabilities are supposed to be assigned only to
propositions that satisfy the clarity test. A statement satisfies
the clarity test if someone in possession of all actual facts, past
present and future, could unambiguously state whether or not the
statement was true. As an example, "Humphrey Bogart was a great
actor," does not satisfy the clarity test. "More than 100 million
people have seen all or part of a Humphrey Bogart movie," would
satisfy the clarity test, provided we gave an unambiguous definition
of "have seen" (e.g., we would need to specify whether a person who
fell asleep before the opening credits and woke up just as the
closing credits were rolling off the screen "has seen" part of the
movie), as well as an unambiguous specification of what counts as a
Humphrey Bogart movie. (04)
I am having trouble figuring out how we can state clarity-test
criteria for specifying truth-values for statements of the form "x
is about y miles from z." Perhaps you have a definition in mind for
what it means, precisely, for the sun to be "about" 93 million miles
from the Earth. You didn't give us a definition. In the absence of
such a definition, how can we determine truth-criteria? (05)
I don't dispute the meaningfulness, the communication value, or the
utility of vague statements. But I don't get what it means for them
to be true. I don't get how such truth-values combine. For example,
if a box weighs about 1 kilogram, and its contents weigh about 2
kilograms, about how much do the box and its contents weigh? If you
give me a set rules for "about arithmetic," I can come up with an
alternate set of rules that is about as reasonable, and gives
different answers on some problems. So then, what is the truth-value
of the statement that the abovementioned box and its contents weigh
about 3 kilograms? (06)
I'd appreciate hearing more about what you think it means for vague
statements to be true. (07)
Thanks, (08)
Kathy (09)
At 4:07 PM -0400 5/10/07, John F. Sowa wrote:
>Ingvar,
>
>I accept the notion of 'truthlikeness' with the option
>of degrees of truthlikeness, as well as many degrees of
>confidence, certainty, approximation, etc.
>
>But I wouldn't equate truthlikeness with truth.
>
>Given Peirce's definition of truth as the ultimate goal that
>might require an indefinite amount of research by indefinite
>number of scientists, it wouldn't make sense to have
>different degrees of truth.
>
>I also accept the fallibilist point that we may already have
>discovered a large number of true statements, but that we
>have no way of being absolutely certain that any particular
>statement is absolutely true (although we may have a very high
>degree of certainty in its degree of approximation).
>
>As I said, I am willing to bet my life on the science and
>engineering that supports our cars and airplanes.
>
>John
>
>
>
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