When do you get a soul? & related questions.

[glaucon]

I'm afraid it does in the case of syllogisms

Alas, no. Still incorrect.
Any syllogism is a formal variation of modus ponens, and as such, all that is required is satisfactory structural arrangement.

If that's the case, The other day was saturday and I was wearing brown shoes therefore I was hungry is a sound argument (since they are all truthful statements)

Again, incorrect.
Regardless of truth value, that's an invalidly formalized (non-)argument.

and (as anyone who has ever come within 10ft of algebra can tell you) a problem of form (as opposed to a problem of content) is a problem of logic

True, but irrelevant here.

 

[lightgigantic]

Alas, no. Still incorrect.
Any syllogism is a formal variation of modus ponens, and as such, all that is required is satisfactory structural arrangement.

feel free to indicate what wearing brown shoes and it being saturday has to do with being hungry then

Again, incorrect.
Regardless of truth value, that's an invalidly formalized (non-)argument.

and the difference between an invalidly formalized argument and an argument that deals specifically with issues of formality (aka logic) is what precisely?

True, but irrelevant here.

given that its only problem is one of form, I doubt it.

 

[glaucon]

feel free to indicate what wearing brown shoes and it being saturday has to do with being hungry then

Absolutely nothing.
You seem to be operating under the assumption that the propositions involved in an argument must somehow be relevant to each other.
That would be incorrect.

and the difference between an invalidly formalized argument and an argument that deals specifically with issues of formality (aka logic) is what precisely?

Nothing.
What you wrote was invalid because it was not properly constructed.

given that its only problem is one of form, I doubt it.

No.
The problem is that you think there needs to be a 'relationship' amongst premises.

 

[wynn]

You seem to be operating under the assumption that the propositions involved in an argument must somehow be relevant to each other.
That would be incorrect.
...
The problem is that you think there needs to be a 'relationship' amongst premises.

If there is no relationship between the premises, if they are not relevant to each other somehow - then how can we say that a conclusion can follow from those premises?

On the basis of what can a conclusion follow from premises, if not on the basis that there is some relationship between them?

 

[glaucon]

If there is no relationship between the premises, if they are not relevant to each other somehow - then how can we say that a conclusion can follow from those premises?


On the basis of what can a conclusion follow from premises, if not on the basis that there is some relationship between them?

Oddly, both yourself and LG seem to be confusing two distinct elements of logic: validity and truth value.

Validity is solely a function of form.
What you're looking for here is a question of truth-value, which is an entirely different thing.


So:

The Aeropagus is a hill.
The Acropolis is a hill.
Therefore, the Aeropagus is the Acropolis.

In this case, both premisses are true, but the conclusion is false.
The problem here is one of validity. This is an invalid logical construction.

Compare:

Phosphorus sometimes rises before the sun.
Venus sometimes rises before the sun.
Therefore, Phosphorus is Venus.

In this case, both premisses are true, and the conclusion is true.
But the argument is still invalid (note the same formal construction as above).

Validity and truth value are distinct, and only contingently related elements of an argument.

 

[lightgigantic]

Absolutely nothing.
You seem to be operating under the assumption that the propositions involved in an argument must somehow be relevant to each other.
That would be incorrect.

and the difference between propositions in an argument that are relevent to each other and logic is what precisely?

Nothing.

If there's no difference its not clear why you are disagreeing

:shrug:

 

[lightgigantic]

Oddly, both yourself and LG seem to be confusing two distinct elements of logic: validity and truth value.

Validity is solely a function of form.
What you're looking for here is a question of truth-value, which is an entirely different thing.


So:

The Aeropagus is a hill.
The Acropolis is a hill.
Therefore, the Aeropagus is the Acropolis.

In this case, both premisses are true, but the conclusion is false.
The problem here is one of validity. This is an invalid logical construction.

Compare:

Phosphorus sometimes rises before the sun.
Venus sometimes rises before the sun.
Therefore, Phosphorus is Venus.

In this case, both premisses are true, and the conclusion is true.
But the argument is still invalid (note the same formal construction as above).

Validity and truth value are distinct, and only contingently related elements of an argument.

If an argument has a problem of form the conclusion has a problem of validity (and hence has a problem of logic).

This is the case with both your arguments.,

So your first argument is neither logical nor truthful.

And the second is not logical but truthful.

The moment you start introducing "truth value" is the moment you are introducing elements outside logic. IOW because we know that the Aeropagus is not the Acropolis, we know we have a problem. This is why computers (instruments of logic) require humans to fix them when they have problems

:shrug:

 

[StrangerInAStrangeLand]

-=-

Another train run off the tracks by bandits.

 

[glaucon]

and the difference between propositions in an argument that are relevent to each other and logic is what precisely?

The difference is that the two are not necessarily related.

If there's no difference its not clear why you are disagreeing

As I've already explained, you're confusing validity with soundness.

 

[glaucon]

If an argument has a problem of form the conclusion has a problem of validity (and hence has a problem of logic).

Incorrect. There is no such thing as a proposition having a 'problem of validity'.
A formally constructed argument can produce both true and false conclusions.

This is the case with both your arguments.,

So your first argument is neither logical nor truthful.

And the second is not logical but truthful.

The moment you start introducing "truth value" is the moment you are introducing elements outside logic. IOW because we know that the Aeropagus is not the Acropolis, we know we have a problem. This is why computers (instruments of logic) require humans to fix them when they have problems

:shrug:

As always, you're confused.
Both arguments are valid, yet each differs with respect to the truth value of the conclusion.

To be clear: truth value and validity are completely different things. While both are contingently related, neither combined result necessarily in a 'true' conclusion.

 

[glaucon]

-=-

Another train run off the tracks by bandits.

Bandit.

 

[lightgigantic]

The difference is that the two are not necessarily related.

I figured that was your take on it .... however I was after details

 

[lightgigantic]

Incorrect. There is no such thing as a proposition having a 'problem of validity'.
A formally constructed argument can produce both true and false conclusions.

an argument is said to be valid when the conclusion is the only tenable offering of the premises.

Because there are other conclusions on offer within your two arguments, neither of them are valid.

:shrug:

An example of a valid argument is given by the following well-known syllogism:

All men are mortal.
Socrates is a man.
Therefore, Socrates is mortal.

What makes this a valid argument is not that it has true premises and a true conclusion, but the logical necessity of the conclusion, given the two premises: the argument would be just as valid were the premises and conclusion false. The following argument is of the same logical form but with false premises and a false conclusion, and it is equally valid:

All cups are green.
Socrates is a cup.
Therefore, Socrates is green.

No matter how the universe might be constructed, it could never be the case that these arguments should turn out to have simultaneously true premises but a false conclusion. The above arguments may be contrasted with the following invalid one:

All men are mortal.
Socrates is mortal.
Therefore, Socrates is a man.

As always, you're confused.
Both arguments are valid, yet each differs with respect to the truth value of the conclusion.

err ... on the contrary, neither of your arguments are valid (although the introduction of an "all" in the right place could do the trick)

To be clear: truth value and validity are completely different things. While both are contingently related, neither combined result necessarily in a 'true' conclusion.

once again, I figured this was your take but I'm after the details of this difference.

 

[glaucon]

I figured that was your take on it .... however I was after details

Such as what?

The details are simple: as far as logic is concerned, propositions are singular elements that need not be 'related' (whatever that means..) in any way to be brought into an argument.

Here's a fully valid argument:

If I am yellow, then I'm a banana.
I am yellow.
Therefore, I am a banana.

This is a valid argument.

No relations, nor indeed, any truth whatsoever concerning the propositions is relevant in any way.

 

[lightgigantic]

Such as what?

The details are simple: as far as logic is concerned, propositions are singular elements that need not be 'related' (whatever that means..) in any way to be brought into an argument.

Here's a fully valid argument:

If I am yellow, then I'm a banana.
I am yellow.
Therefore, I am a banana.

This is a valid argument.

No relations, nor indeed, any truth whatsoever concerning the propositions is relevant in any way.

great

now that you have provided an example of a valid argument, please provide an example of a logical one (one that busies itself merely with issues of form and not content) and lets see if we can spot the difference.

 

[glaucon]

an argument is said to be valid when the conclusion is the only tenable offering of the premises.

Exactly. Notice, no mention of truth.
Any correctly formalized argument will result in a correct conclusion.

Because there are other conclusions on offer within your two arguments, neither of them are valid.

Incorrect.
This merely brings into question the truth value of the conclusions...

What makes this a valid argument is not that it has true premises and a true conclusion, but the logical necessity of the conclusion, given the two premises: the argument would be just as valid were the premises and conclusion false. The following argument is of the same logical form but with false premises and a false conclusion, and it is equally valid:

Exactly.
Notice how truth value of the propositions is irrelevant.

err ... on the contrary, neither of your arguments are valid (although the introduction of an "all" in the right place could do the trick)

Incorrect.
And, by the way, introducing the existential quantifier "All" would simply move this beyond predicate logic into syllogistic logic. The forms of logic applay to all logic systems.

 

[glaucon]

great

now that you have provided an example of a valid argument, please provide an example of a logical one

There's no such difference.
A logical argument is one that is valid.

(one that busies itself merely with issues of form and not content) and lets see if we can spot the difference.

You're not making sense.
'Issues of form' are exactly (and solely) what determine validity.
Content is irrelevant.

 

[StrangerInAStrangeLand]

Such as what?

The details are simple: as far as logic is concerned, propositions are singular elements that need not be 'related' (whatever that means..) in any way to be brought into an argument.

Here's a fully valid argument:

If I am yellow, then I'm a banana.
I am yellow.
Therefore, I am a banana.

This is a valid argument.

No relations, nor indeed, any truth whatsoever concerning the propositions is relevant in any way.

It is a valid conditional argument due to if(s).
Premises not reasonably thought to be true can not make a valid argument or a logical argument. Rather they simply make a mindless muddled mess.

 

[wynn]

Content is irrelevant.

What is the use of logic then?

 

[glaucon]

It is a valid conditional argument due to if(s).

Correct.

Premises not reasonably thought to be true can not make a valid argument or a logical argument. Rather they simply make a mindless muddled mess.

As you noted above, it does indeed make a valid argument. Validity is a function of form solely. You are correct in that, given untrue or unsound premisses, even a valid argument will result in a muddled conclusion. All I was explaining is that there is a distinct difference between validity, truth, and soundness. Validity is a necessary, though not sufficient condition of a true conclusion.

What is the use of logic then?

See my comments above.
Also, the 'use', as far as form goes, is to distinguish between valid reasoning, and invalid reasoning.