I need a Logician

[James_No_2]

I don’t like it, Russiantank.

But then, I am not a logician. However I will take a stab at it for fun.

If you want it to follow from the premises, try this;

(A)

1. The sun will always rise in the east.
2. Tomorrow is a part of always.
3. Therefore the sun will rise in the east tomorrow.

This is a good, circular argument.

However if you want you might do this;

(B)

1. The sun has risen in the east every day in the past.
2. Iff tomorrow is a day like every other, then
3. Tomorrow the sun with rise in the east.

This is not deductive though. Remove the “iff” from (2), to make it deductive. However this makes (B) an example of (A).

Your first statement seems timeless. You might replace ‘always’ with ‘has always done’, or ‘will always do’. The latter leads to circularity, the former, it seems, to induction.

Regards,

James

[pxc]

How about this:

Tomorrow is when the sun next rises.
East is defined as the area the sun rises in.
The sun will rise in the east tomorrow.

[James_No_2]

Dammit read my post! I WORKED FOR THAT POST!! - pxc

etymology

What of those places near the poles which are dark for months on end?

Will there be one continuous day after a nuclear holocaust?

I think in logic we might seperate out the contigent from the necessary. If we can say that we will still have a day even though no sun rises, then your attempt to construct an analytical statement with the use of etymological trickery will have failed.

This is not a straightforward topic. (understatement of the year)

Regards,

James

[Russiantank]

Damn, im confused. I thought this form:

1. A
2. Therefore A

was invalid, but I guess circularity is not invalid… By what standards of logic than can a circular argument be considered illogical?

And, someone please tell me, is this argument circular or invalid:

1. If the sun rises, it rises in the east.
2. The sun rises once every day.
3. Tomorow is a day
4. Therefore, the sun will rise once in the east tomorow.

[pxc]

lol its not really worth figuring out at this point. I’ll check on this thread later.

Cheers.

[James_No_2]

Sorry RT I am a little busy for this right now (need to complete paperwork for my overseas study next year)…

1. If the sun rises, it rises in the east.
2. The sun rises once every day.
3. Tomorow is a day
4. Therefore, the sun will rise once in the east tomorow.

Can there be a tomorrow without the sun rising? This is what you are saying;

1.The sun rises once every day = “it is essential that a day include the rising of the sun.”
translation = the sun rises once every sun rise.
2. Tomorrow is a day = “tomorrow there will be a sun rise”
3. therefore, the sun will rise tomorrow

=circular

Or else you are asserting that, because there has always been a sunrise every day, iff tomorrow is a day, then it will occasion a sunrise.

= induction

does “sun rise” = “day”?

a = a
therefore (necessarily) a = a
iff (it is possible that) a (does not equal) b
then a (does not equal) b

Kripke has given the logicians their toys back, methinks.

Regards,

James

[Russiantank]

First of all, let us forget the connection between a day and the sun rising. I define a day as the passing of 24 hours on a watch starting at 12:00 AM.

"Or else you are asserting that, because there has always been a sunrise every day, iff tomorrow is a day, then it will occasion a sunrise.

= induction"

I do not see this as induction, or valid. It does not follow that because the sun has risen within a 24 hour period (day) every time in the past, that it will do so tomorow. The conclusion does not follow from the premises. Such an argument is invalid. If the premise though is that “The sun rises once every day” than indeed a conclusion that the sun will rise once tomorow follows from this premise.

But you say such an argument is circular? Because the conclusion is implied in the premises. Well than, does anyone care to give me a valid argument that is NOT circular? It seems to me, that for a conclusion to FOLLOW from the premises, the premises must somehow originally contain the conclusion. So it seems to me, by defenition of a valid argument, all valid arguments are circullar…

Let me try, this here is the example of the first logical argument I was ever tought in a philosophy class:

If it rains, it is wet.
It is raining.
Thus it is wet.

This is modus ponens, I was told it is valid and sound. But it is circullar. By the first premise, wetness is implied by rain. The conclusion is contained within the premise… Seems like circularity, or begging the question to me.

[Impenitent]

if it rains, it is wet
it rains
.:it is wet

yes, classic modus ponens…

that is a rule of inference, not induction

the conclusion is not contained within the premise because it only is wet if it rains… if it rains

if the sun rises, it will be in the east
the sun rises
.:it is in the east

that is valid and sound. it does not say the sun must rise because it has done so in the past, all it says is that if the sun happens to rise, it will do so in the east… it does not guarantee that a sun rise will occur…

-Imp

[Hassooni]

Alderian,

i think your abstract is annoying him…

[pxc]

@Impenitent

if it rains, it is wet
it rains
.:it is wet

yes, classic modus ponens…

that is a rule of inference, not induction

the conclusion is not contained within the premise because it only is wet if it rains… if it rains

if the sun rises, it will be in the east
the sun rises
.:it is in the east

that is valid and sound. it does not say the sun must rise because it has done so in the past, all it says is that if the sun happens to rise, it will do so in the east… it does not guarantee that a sun rise will occur…

-Imp

Then you could say “If tomorrow comes, the sun will rise in the east.”

[Impenitent]

if tommorow comes…

-Imp

[ravencry4all]

1. The sun always rises in the east.

2. Tomorow is a part of always.

3. The sun will rise in the east tomorow.

Your argument is valid!!!

If point 1 and 2 are assumed than point 3 is a logical conclusion.
Since there is only one common point in point 1 and 2 it can not be circular.

• the common point is ‘always’

[inhahe]

@Russiantank

Quick question to any logicians. Is this argument valid? I dont care about soundness, only if this argument is valid:

1. The sun always rises in the east.

2. Tomorow is a part of always.

3. The sun will rise in the east tomorow.

Or is this argument circular?

all toast lands on the buttered side.

my toast is a part of all toast.

my toast will land or has landed on the buttered side.

–what if i don’t drop my toast?

is it possible that ‘the sun always rises in the east’ is another way of saying, ‘when the sun rises, it rises in the east?’

so logically, the sun might not rise in the east tomorrow because it might not rise.

i dunno, just a thought.

it seems hard to fit ‘always’ into formal logic. it seems presumptuous infer that days have anything to do with it.

the sun always rises in the east.

2 seconds from now is a part of always.

therefore, the sun will rise in the east 2 seconds from now.

[Russiantank]

Imp,

“the conclusion is not contained within the premise because it only is wet if it rains… if it rains”

Yea, and the sun will rise once tomorow if the sun rises once every day… if the sun rises once every day. No Imp, theres absolutely no diffirence between the arguments. And does the modes ponens argument all of a sudden change if I add this:

If it rains, it is wet.
Tomorow it will rain.
Therefore, tomorow it will be wet.

That is still modus ponens. It is not circular just because it tries to predict the future. “If it rains, it is wet” : Contained in that statement is that whenever it rains, it is wet, that wetness always acompanies rain. Wetness will acompany rain in the past (It rained yesterday, thus it was wet), in the present (it is raining, thus it is wet), and in the future (it will rain, thus it will be wet)

“If it rains, it is wet” is a general prinicple. It DOES NOT say “Whenever it has rained, it has been wet” From this, the future statements could not follow. We could only conclude from this that “It rained yesterday, thus it was wet” But this is not the case. The first premise is a general principle that applies to past, present, and future. As is the case with my argument. I do not say that “The sun has risen once every day” because the sun rising once tomorow does not follow from this. I state a more general principle: “The sun rises once every day”. Contained within this statement is that the sun rising will always acompany a passing of 24 hours, a day. Past, present and future. Bassicly, here is how the two arguments correspond: (each line is the equivilent of the other arguments line)

1. If it rains, it is wet : If it is a day, the sun rises once (The sun rises once every day)

2. It will rain tomorow : It will be a day tomorow (Tomorow is a day)

3. Thus, it will be wet tomorow: Thus, the sun will rise once tomorow

These two are valid. Not sound, because the premises are not neccissarily true. But if you can call these circular, than any valid argument must be called circullar, or begging the question. Does anyone disagree?

[TheAdlerian]

This created a fire storm!

[Dunamis]

1. If it rains, it is wet : If it is a day, the sun rises once (The sun rises once every day)

2. It will rain tomorow : It will be a day tomorow (Tomorow is a day)

3. Thus, it will be wet tomorow: Thus, the sun will rise once tomorow

These two are valid.

"Is that the sound of a 122mm cannon-shell from a Russian Tank landing with devastating force that I hear???

Dunamis

[TheAdlerian]

I believe that this thread may be dangerous to the mental health!

[Impenitent]

@Russiantank

Imp,

“the conclusion is not contained within the premise because it only is wet if it rains… if it rains”

Yea, and the sun will rise once tomorow if the sun rises once every day… if the sun rises once every day. No Imp, theres absolutely no diffirence between the arguments. And does the modes ponens argument all of a sudden change if I add this:

If it rains, it is wet.
Tomorow it will rain.
Therefore, tomorow it will be wet.

[b]yes, it does change. you have introduced “tomorrow it will.” that is not a empirical state of affairs, it is an assumption. notice the difference.

if it rains, it is wet
it rains ****if tommorow appears it will rain tommorrow
.:it is wet ****if tommorow appears it will be wet [/b]

That is still modus ponens. It is not circular just because it tries to predict the future. “If it rains, it is wet” : Contained in that statement is that whenever it rains, it is wet, that wetness always acompanies rain. Wetness will acompany rain in the past (It rained yesterday, thus it was wet), in the present (it is raining, thus it is wet), and in the future (it will rain, thus it will be wet)

yes, but it does not guarantee the event of tomorrow

“If it rains, it is wet” is a general prinicple. no that is a definition It DOES NOT say “Whenever it has rained, it has been wet”

that is exactly what it says.

From this, the future statements could not follow.

the future statements do not follow.

We could only conclude from this that “It rained yesterday, thus it was wet” But this is not the case.

but that is exactly the case.

The first premise is a general principle that applies to past, present, and future.

no, you’d like to apply it to the future, but it only applies to the past and the present, the future hasn’t happened.

As is the case with my argument. I do not say that “The sun has risen once every day” because the sun rising once tomorow does not follow from this. I state a more general principle: “The sun rises once every day”. Contained within this statement is that the sun rising will always acompany a passing of 24 hours, a day.

and contained within your statement is the assumption that an event will occur tomorrow. it is an assumption. it begs the question.

Past, present and future. Bassicly, here is how the two arguments correspond: (each line is the equivilent of the other arguments line)

1. If it rains, it is wet : If it is a day, the sun rises once (The sun rises once every day)

2. It will rain tomorow : It will be a day tomorow (Tomorow is a day)

tomorrow may not occur… this assumes facts not in evidence.

3. Thus, it will be wet tomorow: Thus, the sun will rise once tomorow

These two are valid. Not sound, because the premises are not neccissarily true. But if you can call these circular, than any valid argument must be called circullar, or begging the question. Does anyone disagree?

[b]a valid argument is of a certain form. nothing more.

all festoons are whatzitz
all whatzitz are oingers
.: all festoons are oingers

that is a perfectly valid argument… perfectly unsound and perfectly illogical… but it is valid.

validity doesn’t mean much does it?[/b]

-Imp

[Wobbly]

@Impenitent

that is a perfectly valid argument… perfectly unsound and perfectly illogical… but it is valid.

validity doesn’t mean much does it?[/b]

-Imp

Valid = Logically valid
Logically valid = logical

[Impenitent]

no, if it is valid it has the correct form

val·id ( P ) Pronunciation Key (vld)
adj.
Well grounded; just: a valid objection.
Producing the desired results; efficacious: valid methods.
Having legal force; effective or binding: a valid title.
Logic.
1 Containing premises from which the conclusion may logically be derived: a valid argument.
2 Correctly inferred or deduced from a premise: a valid conclusion.

il·log·i·cal ( P ) Pronunciation Key (-lj-kl)
adj.
Contradicting or disregarding the principles of logic.
Without logic; senseless.

-Imp