If mortality is a necessary property of being human then "All men are
mortal" means what it says.

But if mortality is not a necessary property of being human then we can
allow an "exception to the rule", or the "unique". For example, we can
say 'all men have feelings, Socrates is a man, but Socrates has no
feelings'.

The inclusion of 'all' gives this statement the force of a rule, and
the exception to it highlights the unique, in this case the
particular case of Socrates. So we grant an "exception to a rule"
for Socrates. We would not grant it if 1) lots of people have no
feelings 2) mortality is a necessary property of being human (or an
analytic truth).

Expressions that present the unique or "allow an exception to the
rule" are common in natural language but not, apparently, in logic.

If logic does not allow the "unique" through an exception to a rule
then there is a local tension between logic and natural language
expressions.

John Jones <jonescardiff at (no spam) aol.com> writes:

If mortality is a necessary property of being human then "All men are
mortal" means what it says.

But if mortality is not a necessary property of being human then we can
allow an "exception to the rule", or the "unique". For example, we can
say 'all men have feelings, Socrates is a man, but Socrates has no
feelings'.

Then the statement "All men have feelings" is false. Big deal.

Necessity really isn't all that relevant.

The inclusion of 'all' gives this statement the force of a rule, and
the exception to it highlights the unique, in this case the
particular case of Socrates. So we grant an "exception to a rule"
for Socrates. We would not grant it if 1) lots of people have no
feelings 2) mortality is a necessary property of being human (or an
analytic truth).

We would not grant an exception to the statement "All men have
feelings" in any case. Either it is true or false.

Now, if you had said, "Men have feelings, but Socrates has no
feelings", you might have a point. The sentence "Men have feelings"
can certainly be taken as a statement about most men, or "normal" men,
but this is not the case with "All men have feelings."

It seems to me that this analysis is perfectly consistent with our
usual interpretations of the following two sentences:

(1) All humans have two legs.

(2) Humans have two legs.

The first sentence is evidently false, since amputees exist.

The
second sentence is plausibly true, although there are exceptions to
the rule it expresses. It is natural to interpret (2) in terms of
some sort of default logic. It is not natural to interpret (1) in
terms of default logic.

Expressions that present the unique or "allow an exception to the
rule" are common in natural language but not, apparently, in logic.

Perhaps you should learn about default logic. Try these pages:

http://plato.stanford.edu/entries/logic-nonmonotonic/
http://en.wikipedia.org/wiki/Default_logic

If logic does not allow the "unique" through an exception to a rule
then there is a local tension between logic and natural language
expressions.

Well, no kidding. What an amazing and origi Woof nal discovery.

Jesse F. Hughes wrote:
John Jones <jonescardiff at (no spam) aol.com> writes:

If mortality is a necessary property of being human then "All men are
mortal" means what it says.

But if mortality is not a necessary property of being human then we can
allow an "exception to the rule", or the "unique". For example, we can
say 'all men have feelings, Socrates is a man, but Socrates has no
feelings'.

Then the statement "All men have feelings" is false. Big deal.

Yes, but 'it's false' does not exhaustively tackle the substance of what
is at issue. Pay attention and don't jump the gun.

The inclusion of 'all' gives this statement the force of a rule, and
the exception to it highlights the unique, in this case the
particular case of Socrates. So we grant an "exception to a rule"
for Socrates. We would not grant it if 1) lots of people have no
feelings 2) mortality is a necessary property of being human (or an
analytic truth).

We would not grant an exception to the statement "All men have
feelings" in any case. Either it is true or false.

But we do grant exceptions of this type. For example, 'everyone's got
brain's except Jesse' is perfectly allowable in natural language. There
would be no alternative expression for 'everyone' except 'all
men/women', which is the same thing.

Now, if you had said, "Men have feelings, but Socrates has no
feelings", you might have a point. The sentence "Men have feelings"
can certainly be taken as a statement about most men, or "normal" men,
but this is not the case with "All men have feelings."

But 'men have fellings' would not allow an exception to a rule, for the
rule is not forcefully apparent here.

It seems to me that this analysis is perfectly consistent with our
usual interpretations of the following two sentences:

(1) All humans have two legs.

(2) Humans have two legs.

The first sentence is evidently false, since amputees exist.

It would make sense to say that 'all humans have two legs except
Jesse'. Here, Jesse would be a unique case and treated as an
exception to a rule.

The
second sentence is plausibly true, although there are exceptions to
the rule it expresses. It is natural to interpret (2) in terms of
some sort of default logic. It is not natural to interpret (1) in
terms of default logic.

But if that's right then for 1) and 2) I can't formulate an
exception to a rule.

Expressions that present the unique or "allow an exception to the
rule" are common in natural language but not, apparently, in logic.

Perhaps you should learn about default logic. Try these pages:

http://plato.stanford.edu/entries/logic-nonmonotonic/
http://en.wikipedia.org/wiki/Default_logic

...'learn'? Logic is not 'learnt'. It is made up, it is a collection of
reminders. It's a sort of phossilised philosophy - the act pictured in
frozen motion.

In the beginning was the deed. What else .. Oh, and that
site wasn't quite what I was on about. "All non-monotonic logics handle
conflicts of the first kind in the same way: indeed, it is the very
essence of defeasible reasoning that conclusions can be retracted when
new facts are learned." - still operating under the old rules.

John Jones <jonescardiff at (no spam) aol.com> writes:

But 'men have fellings' would not allow an exception to a rule, for the
rule is not forcefully apparent here.

No idea what you mean.

It would make sense to say that 'all humans have two legs except
Jesse'. Here, Jesse would be a unique case and treated as an
exception to a rule.

But FOL makes perfect sense of sentences like, "All humans have two
legs except Jesse," so what are you on about?

You could perfectly well capture that sentence as:

(Ax)(Human(x) -> (x = Jesse v TwoLegs(x))) & ~TwoLegs(Jesse).

You began by claiming that the following three sentences are
consistent in a plain English reading:

All men are mortal.
Socrates is a man.
Socrates is not mortal.

I deny that those are consistent.

Now you seem to be headed off the rails.

Jesse F. Hughes wrote:
John Jones <jonescardiff at (no spam) aol.com> writes:

But 'men have fellings' would not allow an exception to a rule, for the
rule is not forcefully apparent here.

No idea what you mean.

'Men have feelings' does not stress the rule concerning men and feelings
in the same way that 'All men have feelings' stresses the rule. The
latter is more forceful, it lays emphasis on the fact that we are
employing a rule. It is only a rule that allows an exception. 'Men have
feelings' doesn't do it. That's why I insist on the inclusion of 'all'.

It would make sense to say that 'all humans have two legs except
Jesse'. Here, Jesse would be a unique case and treated as an
exception to a rule.

But FOL makes perfect sense of sentences like, "All humans have two
legs except Jesse," so what are you on about?

You could perfectly well capture that sentence as:

(Ax)(Human(x) -> (x = Jesse v TwoLegs(x))) & ~TwoLegs(Jesse).

What?

You began by claiming that the following three sentences are
consistent in a plain English reading:

All men are mortal.
Socrates is a man.
Socrates is not mortal.

I deny that those are consistent.

I think there is a historical influence at work here, and it is
triggered by the image of the classic three-tiered structure presented
above. I think if we broke up the image of that structure we would be
less influenced by the demands that this particular visual logical
tradition makes upon thinking. So, with respect to the visual example
All men are mortal.
Socrates is a man.
Socrates is not mortal,
we would feel less constrained by long tradition to say 'I deny the
consequences', if we broke up its visual presence.

Now you seem to be headed off the rails.

All I'm saying is this:
To allow an exception to a rule, we must first have a rule. "All men are
mortal" expresses a rule; but "Men are mortal" does not express a
rule.

So on that basis, my argument is surely correct:
If "all men are mortal", and
"Socrates is a man" then,
that "Socrates is not mortal" is not false, but an exception to a rule.

Again, you seem to have trouble with basic English. If all men are
mortal and Socrates is a man, then Socrates is mortal.

OK. Importantly, what I am also arguing here is that the failure of
logic to allow an exception to a rule is symptomatic of its failure
to make a distinction between a contingent property (or 'condition')
and a necessary property.

Do not be carried away by the force of omnipresent tradition. Every man
would think it strange if he heard that in the land there was a man who
believed that standardised logic had the power to persuade through its
VISUAL impact. But John Jones is a man and John Jones does not think it
strange.

OK. Importantly, what I am also arguing here is that the failure of
logic to allow an exception to a rule is symptomatic of its failure
to make a distinction between a contingent property (or 'condition')
and a necessary property.

The main failure I see is your failure to understand plain English
sentences.

And I don't see any reason to continue this conversation. No idea why
I entered it in the first place.

On May 20, 11:28 pm, John Jones <jonescard... at (no spam) aol.com> wrote:

I can say without confusion "all swans are black or white, but Farmer
Brown's swan is pink".

Guffaw.

JJ's usual complete bollocks of course.

Jesse F. Hughes wrote:

Again, you seem to have trouble with basic English. If all men are
mortal and Socrates is a man, then Socrates is mortal.

Then, logic does not allow an exception to a rule.
But -

IF we allow an exception to a rule, then we can make a useful
distinction between a contingent property/condition and a necessary
property/condition. This is because only the former (contingent
property) allows an "exception to a rule":

Contingent property:
I can say without confusion "all swans are black or white, but Farmer
Brown's swan is pink". It is not a necessary condition that swans are
black or white -, it is a contingent, accidental truth that all swans
are black or white, and so I AM GRANTED an exception to a rule.

Necessary property:
I CAN'T say "all swans have a colour, but Farmer Brown's swan has no
colour". In other words, it is a necessary condition that swans have a
colour in order that they are allowably classed as swans. Here, I am NOT
GRANTED an exception to a rule.

OK. Importantly, what I am also arguing here is that the failure of
logic to allow an exception to a rule is symptomatic of its failure to
make a distinction between a contingent property (or 'condition') and a
necessary property.

3) the failure to acknowledge or provide a term for a 'unique'

John Jones wrote:
Jesse F. Hughes wrote:

Again, you seem to have trouble with basic English. If all men are
mortal and Socrates is a man, then Socrates is mortal.

Then, logic does not allow an exception to a rule.
But -

IF we allow an exception to a rule, then we can make a useful
distinction between a contingent property/condition and a necessary
property/condition. This is because only the former (contingent
property) allows an "exception to a rule":

Contingent property:
I can say without confusion "all swans are black or white, but Farmer
Brown's swan is pink". It is not a necessary condition that swans are
black or white -, it is a contingent, accidental truth that all swans
are black or white, and so I AM GRANTED an exception to a rule.

Necessary property:
I CAN'T say "all swans have a colour, but Farmer Brown's swan has no
colour". In other words, it is a necessary condition that swans have a
colour in order that they are allowably classed as swans. Here, I am
NOT GRANTED an exception to a rule.

OK. Importantly, what I am also arguing here is that the failure of
logic to allow an exception to a rule is symptomatic of its failure to
make a distinction between a contingent property (or 'condition') and
a necessary property.

What're you getting at? You say logic doesn't make a distinction between
contingent and necessary properties. What about the assertion "some
swans are black or white"?

You seem to be saying that logical quantifiers don't match up perfectly
with quantifiers in ordinary language. But that's well-known.