Logic

[puppydog85]

In the course of several discussions the word illogical has been thrown around and has caused me to think that most people here don't know what "a logical argument" means.

So the poll I wanted to start would go like this.

Is this statement: A. Logical B. Illogical

All horses are pink
I have horse
Therefore my horse is pink


Courtesy of C.S. Lewis
“Logic!” said the Professor half to himself. “Why don’t they teach logic at these schools?"

[crispybits]

The conclusion is logically valid given the premises, but the premise "All horses are pink" is obviously false.

[Nendreel]

Non-pink pony. Your premise of all pink horses is therefore false.

I moslty just wanted to post a picture of ponies

[AndyDufresne]

Non-pink pony. Your premise of all pink horses is therefore false.

I moslty just wanted to post a picture of ponies

Laughing Man approved.


--Andy

[Haggis_McMutton]

[bedub1]

Is this statement: A. Logical B. Illogical

All horses are pink
I have horse
Therefore my horse is pink

All horses are pink
I have a pink animal
Therefore the animal is a horse.

[crispybits]

I call affirming the consequent! (sorry, I'm getting all technical now but I'm trying to stay in logic mode for when puppy replies to me in another thread)

[jonesthecurl]

How 'bout this one?


The universe must have been created
Only God can create.
Therefore the Bible is true.



Does that work, or might there be a flaw in the logic, the premises, or the conclusion?

[crispybits]

I think that one is very loosely described as either "begging the question" or "preaching to the choir" where I'm concerned

[nietzsche]

I don't get what OP is trying to point out?

The statement is logical. Whether the premises are true or not, that's another matter. Maybe that's what he's pointing out? Sorry I'm not following the other threads.

[Frigidus]

It is, in fact, logically valid. However, the argument is logically unsound as the premises are false.

http://www.iep.utm.edu/val-snd/

Edit: What point are you trying to make here?

[Lootifer]

He's saying that you can still be logical while having an unconfirmed premise.

Its just a pity that he used such a falsifiable premise. Not all horses are pink thus your statement is wrong.

You needed to put some pragmatic unknowns into your example. Being a helpful chap here:

All trees that fall in a forest with no conscious observers make no sound.
A tree recently fell down in my back yard and there was no conscious observers around to hear it.
Therefore it made no sound.

[puppydog85]

I just wondered how many people thought that logical= a correct argument. Not as many as I thought, but based on how many people toss around the word logical I was expecting a bit more.

[PLAYER57832]

In the course of several discussions the word illogical has been thrown around and has caused me to think that most people here don't know what "a logical argument" means.

So the poll I wanted to start would go like this.

Is this statement: A. Logical B. Illogical

All horses are pink
I have horse
Therefore my horse is pink


Courtesy of C.S. Lewis
“Logic!” said the Professor half to himself. “Why don’t they teach logic at these schools?"

It is logical, but is it true? That is a different question, entirely.

And, part of knowing if that statement is really logical is knowing if the statement is true, could be true or is plain false. Most people want to stop at the surface, when the real problem is at the far more basic level, not "is it logical", but " is what I understand true?".

[puppydog85]

Sorry player but that sounded contradictory to me. Perhaps I misunderstood.

It is logical, but is it true? That is a different question

if that statement is really logical is knowing if the statement is true

What do you mean when you say "really"?

[pickleofdoom]

Here is a statement taken from the classic topology textbook by Munkres:

Let x be a real number.
If x^2 < 0 then x =23

true or false?


what about this:

Let x be a real number.
If x^2 < 0 then 1+1 =23

?

[PLAYER57832]

Is this statement: A. Logical B. Illogical

All horses are pink
I have horse
Therefore my horse is pink

All horses are pink
I have a pink animal
Therefore the animal is a horse.

This is not logical. It is a fallacy, becuase you have not established that horses are the only pink animals, just that all horses are pink.

[pickleofdoom]

All Greeks are mortal.
The Pickle of Poom is not a Greek.
Therefore the PoD lives on mount Olympus and plays chess with little Ray Harryhausen figures of minotaurs and stuff.

Is that true, or is it a silly-gysm?

[Haggis_McMutton]

Here is a statement taken from the classic topology textbook by Munkres:

Let x be a real number.
If x^2 < 0 then x =23

true or false?


what about this:

Let x be a real number.
If x^2 < 0 then 1+1 =23

?

[PLAYER57832]

How 'bout this one?


The universe must have been created
Only God can create.
Therefore the Bible is true.



Does that work, or might there be a flaw in the logic, the premises, or the conclusion?

All of the above.

Its what atheists try to claim theists use for logic, not the truth.

begin with:
The universe is. Was it created or always here? We don't actually know.

[Frigidus]

I just wondered how many people thought that logical= a correct argument. Not as many as I thought, but based on how many people toss around the word logical I was expecting a bit more.

The key here is that the term "logical" is more of a descriptive word than a technical term. The qualifiers that are used in logic to describe arguments are 'validity' and 'soundness'. I'll just paste this from the article I linked earlier.

It is important to stress that the premises of an argument do not have actually to be true in order for the argument to be valid. An argument is valid if the premises and conclusion are related to each other in the right way so that if the premises were true, then the conclusion would have to be true as well. We can recognize in the above case that even if one of the premises is actually false, that if they had been true the conclusion would have been true as well. Consider, then an argument such as the following:

All toasters are items made of gold.
All items made of gold are time-travel devices.
Therefore, all toasters are time-travel devices.

Obviously, the premises in this argument are not true. It may be hard to imagine these premises being true, but it is not hard to see that if they were true, their truth would logically guarantee the conclusion’s truth.

It is easy to see that the previous example is not an example of a completely good argument. A valid argument may still have a false conclusion. When we construct our arguments, we must aim to construct one that is not only valid, but sound. A sound argument is one that is not only valid, but begins with premises that are actually true. The example given about toasters is valid, but not sound. However, the following argument is both valid and sound:

No felons are eligible voters.
Some professional athletes are felons.
Therefore, some professional athletes are not eligible voters.

Here, not only do the premises provide the right sort of support for the conclusion, but the premises are actually true. Therefore, so is the conclusion. Although it is not part of the definition of a sound argument, because sound arguments both start out with true premises and have a form that guarantees that the conclusion must be true if the premises are, sound arguments always end with true conclusions.

[PLAYER57832]

And that, fundamentally is why the atheistic arguments fail, and why it is so important for some militant atheists to disprove the idea of God.

Because, when you start with the idea that the basis of what many people believe is just false, then it is easy to declare their thinking illogical.

To someone who has never seen a "vision", or heard what they believe to be a true voice of God, the whole idea that it could happen may seem ridiculous. But, if it has happened to the person, then it is logical that they might listen. NOW.. the tricky part is that many people do "hear voices" and such in ways that are just plain incorrect. In fact, many people claim religious enlightenment, but others will say "no, that was not true". (George W. Bush comes to mind, there)

To take the original example... most of us know that horses are not pink, except.. well, they can be dyed and genetic engineering might create a pink horse. Furthermore, even if no horse is pink, does that mean that no animal is pink or that pink animals are not possible? In fact, we know pink animals are not very common here in North America, but they are found elsewhere commonly.

So, logically, someone from, say Michigan might honestly believe there are no pink aminals. A person from Africa will disagree.

[BigBallinStalin]

And that, fundamentally is why the atheistic arguments fail, and why it is so important for some militant atheists to disprove the idea of God.

Because, when you start with the idea that the basis of what many people believe is just false, then it is easy to declare their thinking illogical.

To someone who has never seen a "vision", or heard what they believe to be a true voice of God, the whole idea that it could happen may seem ridiculous. But, if it has happened to the person, then it is logical that they might listen. NOW.. the tricky part is that many people do "hear voices" and such in ways that are just plain incorrect. In fact, many people claim religious enlightenment, but others will say "no, that was not true". (George W. Bush comes to mind, there)

To take the original example... most of us know that horses are not pink, except.. well, they can be dyed and genetic engineering might create a pink horse. Furthermore, even if no horse is pink, does that mean that no animal is pink or that pink animals are not possible? In fact, we know pink animals are not very common here in North America, but they are found elsewhere commonly.

So, logically, someone from, say Michigan might honestly believe there are no pink aminals. A person from Africa will disagree.

Um... what are you referring to when you say "and that..."?

And how does the atheistic argument fail? What is that argument exactly? Could you outline it for us?

[Phatscotty]

And that, fundamentally is why the atheistic arguments fail, and why it is so important for some militant atheists to disprove the idea of God.

Because, when you start with the idea that the basis of what many people believe is just false, then it is easy to declare their thinking illogical.

...and bigoted...

[crispybits]

No, we should all start with the premise that everything based on belief is unproven until such time as proof is provided. Not false or true, just unproven.

This includes our own views. If I say that "all normal healthy horses have 4 legs, 2 eyes and one heart" then that is an unproven statement. So we go out and look at hundreds and thousands of horses, and find that all normal healthy healthy horses (as in ones not suffering from deformity or injury) have 4 legs, 2 eyes and 1 heart.

This information need not be personally collected by us, we are able to accept that observations made by others and recorded / broadcasted are equally valid, so long as those observations are universal, as in everyone can go and make the same observation about the same thing without prejudice.

Someone from Michigan may well believe that there is no such thing as a pink animal, but belief is not truth, and all that would be required would be to bring them to Africa (or even just to a nearby zoo) and show them a flamingo and they would realise that their belief had been incorrect.