# I NEED ANOTHER LOGICIAN (TO SHOW IMP HOW WRONG HE IS!)

Argument:

All As are Bs
All Bs are Cs
Thus All As are Cs

Imp and I use diffirent defenitions of both “Valid” and “Follows” Let me explain. My understanding of “Valid” is that it is in propper form. What is propper form?

Propper form is such a form in which the Conclusion must follow from the Premises. This is propper form. The above argument is in propper form. It is thus Valid. What does follow mean? I cannot give a concise defenition, but it probably has something to do with the rules of inference or something. But I can tell when an argument is valid. Most people can. Modes Ponens is valid. In that the conclusion follows from the premises.

Here is an example of a conclusion following from premises:

If A, Then B
A
Thus B

Heres an example of NOT following.

If A, Then B
A
Thus G

I understand “following” best in terms of the transitive property in Math.

X=Y
Y=5
Thus, X=5

Now, Imp on the other hand, has diffirent ideas:

For Imp, Modes Ponens:

If A, Then B
A
Thus B

would be INVALID if the premises were not true. He said that any argument with a logical fallicy can be considered invalid. And that false premises are a logical fallicy. For me, this is the popular usage of the word invalid. Talking to someone not schooled in logic, I may say, “No, thats an invalid argument” which for me means not good bassicly. But again, in my logic classes, I learned that validity has only to do with form. A form is valid if the conclusion follows from the premises. Now what is follows for Imp?

For Imp, “follows” apparently means that a conclusion must be true. For a conclusion to “follow” from its premises, the premises must be true, and thus the conclusion too is true.

What is the point of all this? We were arguing if a True Conclusion could follow from False Premises. Using Imps defenition, you can see why a True conclusion cannot follow from false premises:

All dogs are fish
All fish are mammals
Thus, all dogs are mammals.

The conclusion here is true, premises false. By Imps defenition of “Follows” the conclusion DOES NOT follow from the premises, because “following” is contingent on the Truth of the premises for Imp. By my defenition of “follows” this example is such that a true conclusion DOES follow from false premises. Just like the transitive property in math, if you replace the objects (dogs, fish, mammals) with numbers and variables (X,Y,5) than you can see how the transitive property would work for this form.

Now the question to the Logicians. Please tell me and Imp which of the defenitions of Valid and Follows, Imps or mine, is the more common one, or more generally accepted among… uh… the logical community?

R.T.,

O.E.D.

Valid (Latin valid-us strong, powerful, effective)-

1. Good or adequate in law; possessing legal authority or force; legally binding, or efficacious.
2. Of arguments, proofs, assertions, etc. Well founded and fully applicable to the particular matter or circumstances; sound and to the point; against which no objection can be raised.

Dunamis

philosophypages.com/lg/e01.htm

"A deductive argument is said to be valid when the inference from premises to conclusion is perfect. Here are two equivalent ways of stating that standard:

If the premises of a valid argument are true, then its conclusion must also be true.
It is impossible for the conclusion of a valid argument to be false while its premises are true.
(Considering the premises as a set of propositions, we will say that the premises are true only on those occasions when each and every one of those propositions is true.) Any deductive argument that is not valid is invalid: it is possible for its conclusion to be false while its premises are true, so even if the premises are true, the conclusion may turn out to be either true or false.
Notice that the validity of the inference of a deductive argument is independent of the truth of its premises; both conditions must be met in order to be sure of the truth of the conclusion.

philosophypages.com/lg/e08b.htm

Establishing Validity

Rules and Fallacies

Since the validity of a categorical syllogism depends solely upon its logical form, it is relatively simple to state the conditions under which the premises of syllogisms succeed in guaranteeing the truth of their conclusions. Relying heavily upon the medieval tradition, Copi & Cohen provide a list of six rules, each of which states a necessary condition for the validity of any categorical syllogism. Violating any of these rules involves committing one of the formal fallacies, errors in reasoning that result from reliance on an invalid logical form.

In every valid standard-form categorical syllogism . . .

1 . . . there must be exactly three unambiguous categorical terms. The use of exactly three categorical terms is part of the definition of a categorical syllogism, and we saw earlier that the use of an ambiguous term in more than one of its senses amounts to the use of two distinct terms. In categorical syllogisms, using more than three terms commits the fallacy of four terms (quaternio terminorum).

2 . . . the middle term must be distributed in at least one premise. In order to effectively establish the presence of a genuine connection between the major and minor terms, the premises of a syllogism must provide some information about the entire class designated by the middle term. If the middle term were undistributed in both premises, then the two portions of the designated class of which they speak might be completely unrelated to each other. Syllogisms that violate this rule are said to commit the fallacy of the undistributed middle.

3 . . . any term distributed in the conclusion must also be distributed in its premise. A premise that refers only to some members of the class designated by the major or minor term of a syllogism cannot be used to support a conclusion that claims to tell us about every menber of that class. Depending which of the terms is misused in this way, syllogisms in violation commit either the fallacy of the illicit major or the fallacy of the illicit minor.

4 . . . at least one premise must be affirmative. Since the exclusion of the class designated by the middle term from each of the classes designated by the major and minor terms entails nothing about the relationship between those two classes, nothing follows from two negative premises. The fallacy of exclusive premises violates this rule.

5 . . . if either premise is negative, the conclusion must also be negative. For similar reasons, no affirmative conclusion about class inclusion can follow if either premise is a negative proposition about class exclusion. A violation results in the fallacy of drawing an affirmative conclusion from negative premises.

6 . . . if both premises are universal, then the conclusion must also be universal. Because we do not assume the existential import of universal propositions, they cannot be used as premises to establish the existential import that is part of any particular proposition. The existential fallacy violates this rule.

[size=167]pay close attention to rule 4[/size]

-Imp

HAHAHA, sorry Imp, you are arguing for me…

Notice that the validity of the inference of a deductive argument is independent of the truth of its premises; both conditions must be met in order to be sure of the truth of the conclusion.”

Thats what im saying. When one says “The conclusion follows from the premises” this means that the inference is valid. The inferance principles guide an argument from the premises to the conclusion.

If A, Then B
A
Thus, I INFER that B.

If the inference of the argument is valid, than the conclusion follows from the premises. BUT LIKE YOU SAID, THE CONCLUSION IS NOT NECISARILY TRUE. For the argument to ensure us that the conclusion is true, we need both conditions to be met, Validity, and truth of premises. Again, Validity in the technical sense is independent of the truth of the premises. And all that this validity means is that the conclusion follows from the premises, like the transitive property. Only that the inference is done correctly! Thats all that valid in this sense means. It means that the conclusion follows from the premise. Listen to this distinction:

My “follows” does not mean “is made true by” though this seems the case for your use of “follows”. All my “follows” means is that it is in propper form. This is literaly what I was tought in my philosophy classes in college:

Valid only means that the conclusion follows from the premises. Here is an example of a valid argument:

If A, then B
A
Thus B

THE TRUTH OF THE PREMISES DOES NOT MATTER. VALIDITY ONLY DEALS WITH THE FORM. AND VALIDITY MEANS THAT THE CONCLUSION FOLLOWS FROM THE PREMISES.

Example of non-valid argument (non-valid because the conclusion DOES NOT follow from the premises)

If A, then B
B
Thus A

This is invalid, because A could occur for any other reason. No where does it say that Bs only come along with As. So that conclusion cannot follow from those premises.

Again, to “follow” means only to be able to be infered. I cannot infer that an A must occur if a B occurs, because I have no reason to think that As always acompany Bs.

“4 . . . at least one premise must be affirmative. Since the exclusion of the class designated by the middle term from each of the classes designated by the major and minor terms entails nothing about the relationship between those two classes, nothing follows from two negative premises. The fallacy of exclusive premises violates this rule.”

This is no argument for you. This whole thing talks only about form. “Affirmitive” and “Negative” are in regards to form. Affirmitive does not mean true, and negative false. Affirmitve means that something is affirmed, example: There IS a God. This premise is affirming a god. “Negative” means negating something. Example: There IS NO God. This just deals with form Imp. It has nothing to do with the truth of the premises. And it makes sense. Try forming a valid argument with only negative premises. You can have 1 negative premise and have a good argument though. Example:

If A, then B (positive premise)
Not B (negative premise)
Thus Not A.

I don’t see the problem. The argument you presented"

All dogs are fish
All fish are mammals

Therefore, all dogs are mammals.

(Which was my example) is clearly a case of a true conclusion which follows from two false premises. So, when Imp. wrote that only a false conclusion can follow from false premises, he was clearly wrong.

What does it mean for a conclusion to follow from the premises? It means that if the premises were true, the conclusion would have to be true. Of course, that does not mean that the either the premises or the conclusion do, in fact have to be true. Here, for instance, is a case in which both the premises and the conclusion are false, yet the conclusion follows from the premises.

All dogs are fish
All fish are reptiles

Therefore, it follows that all dogs are reptiles.Both premises are false. The conclusion is false. The argument is valid.

Imp need to repeat his course in Logic 101.

-Imp

the form of the argument is valid, but the argument is fallacious. fallacious arguments are invalid.

-Imp

Imp, you are the one terribly confused. Learn to interpret what you read.

“what part of “both conditions must be met in order to be sure of the truth of the conclusion” don’t you understand?”

I understand it fine. But its no argument for you. It doesnt say:

“Both conditions must be met in order to be sure that the conclusion follows from its premise”

No, thats not what it says, it says:

“both conditions must be met in order to be sure of the truth of the conclusion”

Which I agree with. What does that have to do with me? We are arguing about what “follows” is… Ive already decided we are just using 2 diffirent defenitions of valid. You are not going to convince me that Valid means what you say it does. And also, youre using the non-technical form of valid. Again, no point in arguing over this, lets ask everyone else:

IN TERMS OF LOGIC, WHAT DOES VALID MEAN? ANYONE WHO KNOWS LOGIC WELL AND WISHES TO SPEAK UP, PLEASE DO!

Also, did you not read what I wrote?

“Notice that the validity of the inference of a deductive argument is independent of the truth of its premises”

Imp, youre only reading what you want to… you dont even care about propper arguing at this point… you just want to win… so sad…

“and you missed it again. NOTHING FOLLOWS FROM FALSE PREMISES. you can have correct form all day long, if the premises are false, the argument is INVALID.”

Define follows please. I already know you are using Invalid diffirently than me, so… By mine and Kennethamy’s defenition, than in fact a conclusion can follow from false premises.

Again, TO ALL LOGICIANS OUT THERE, WHAT DOES “FOLLOWS” MEAN WHEN WE SAY: “THE CONCLUSION FOLLOWS FROM THE PREMISES”

Lets see what they think eh?

[b]Wait…

“follows” means directly [size=150]inferred[/size] from the premises."

NOW PAY ATTENTION!!!

NOW COMBINE THIS LAST STATEMENT WITH THIS ONE:

“Notice that the validity of the [size=150]inference[/size] of a deductive argument is independent of the truth of its premises”

[size=150]INFERENCE IS INDEPENDENT OF THE TRUTH OF THE PREMISES![/size] SO BY YOUR OWN DEFENITION OF “FOLLOWS”, the truth of the premises has nothing to do with it![/b] But ofcourse you will ignore this and keep on plowing along your stuborn path… What can we do?

“what part of BOTH CONDITIONS do you not understand?!?”

Let me just repeat myself…

BOTH CONDITIONS refers to the TRUTH of the argument. SEE:

“both conditions must be met in order to be sure of the truth of the conclusion.”

But we are not arguing about the truth of the conclusion. We ALREADY KNOW that the conclusion is true! Dogs are mammals is a true conclusion, no matter how you aquire it. So this statement of yours that you repeated twice, MAKES NO POINT TO ME! I agree with it, and always did. The truth of a conclusion rests on TWO factors:

1. Valid Form (Meaning the conclusion follows from the premises)

2. True Premises.

But again, who cares about the truth of the conclusion? Thats not our argument.

Now to affirmitive and negative propositions

First of all, why didnt that site just say “true” premises and “false” premises? Why decide to use affirmitive and negative? Because they mean something diffirent silly…

Now look, this is word for word from the Oxford Companion to Philosophy, and theyre prety good at what they do:

affirmative and negative propositions. Given any proposition p, it is possible to form its negation, not-p. Since not-p is itself a proposition, it in turn has its negation, not-not-p, which in classical logic is equivalent to p.

It goes on to talk about whether or no not-not p and p are the same, but you get the idea. True and False have no place here. Ever watched an army movie? What do they say when asked a question?

“Affirmitive sir”

or

“Negative sir”

Is the soldier saying, “True” and “False” or “yes” and “no”?

Would you say: “True” or “Yes sir, I did get my target”

Figure it out Imp…

This is all pointless. You will read what you want and ignore the rest just so you can maintain your argument…

Can a logician please comment? I need to show Imp how silly he is…

I was taught that in philosophical circles, a “valid” argument is one in which the conclusion follows from the premises – regardless of the truth of the premises. If an argument was valid and its premises were true, then we called the argument “sound”.

But who cares? If you want to know how the word “valid” is generally used in philosophy, you can ask the philosophical community to vote on it or something. If you want to use the word in a certain way, all that’s required is that the parties involved agree on a meaning.

i dont know, maybe im drunk, maybe stupid. maybe this is way the hell more complicated than it has to be.

as far as ive seen, imp scepticism is based mainly on the inductive fallacy. in order for you to know that all As are Bs to form the first part of your syllogism, you need to use induction. because you cant just use syllogisms to know all truths because where did your premises come from?

you cant find any truth using inductive reasoning because inductive reasoning is based on “the future will resemble the past, because, in the past, the future resembled the past” and thats a self fulfilling prophecy. you cant say that a piece of meat, when left alone, will spontaneously generate maggots simply because every time youve left one out, maggots appeared. because you forgot to try leaving a piece of meat in a vacuum. you forgot to make sure that As might not be Bs in some certain circumstances.

its so amazingly simple. ive just written an exhaustive response to the first post. you dont know that all As are Bs, you cant know. if you assume they are, then yeah go ahead and assume whater you want is true. but its not actually going to be true. i suppose thats good for ‘philosophy’ but the real world likes induction. without it, humans would behave a lot like monkeys.

as for ‘valid’, ill agree and say that it can rely on assumptions just fine. and ‘sound’ means the assumptions are sound as well. gold star aporia.

logic is my bitch. i want a showdown with you imp, or anybody. a real test of verbal and logical abilities. i will destroy you. i will bet any amount of money. and im not saying that because i doubt your abilities, i just have faith in mine like people have faith in jesus. friends, direct your logical questions to me. i know all… given premises.

How about putting a lid over the meat while leaving it out? Then they would at least wonder why the sun is not causing maggots. (Yes, the medievals were not big on experimental science.)

Now I don’t want your money, and I don’t want a competition, but I think applying induction to cases where time is an issue, might be of less value than when they are used to determine universal properties which are not affected by time: like the statement “man is a rational animal”. So induction can be knowledge, and hence so can syllogisms.

Am I foolish speaking with you like this?

my real name

And yet there have been arguments for necessary aposteriori truths, and contigent apriori truths, for more than 30 years now. Certainly not uncontended arguments, but nothing that has been conclusively refuted either.

Just a thought.

Regards,

James

[b]did you see it yet? [size=167]did you see it?[/size]

"The truth of a conclusion rests on TWO factors:

1. Valid Form (Meaning the conclusion follows from the premises)

2. True Premises."

what is #2?

All dogs are fish false premise
All fish are mammals false premise

Therefore, all dogs are mammals. rests on the truth of the premises?

[/b]

-Imp

Changing the subject Imp? Hehehe

Imp, let me explain. For an argument to show that a conclusion is true, you have to have true premises. But from the VERY begining, when Knennethamy first said that you can have a true conclusion follow false premises, the truth of the conclusion was assumed.

All dogs are mammals

How do we know this is true? NOT, I REPEAT NOT BECAUSE OF THIS ARGUMENT:

All dogs are fish
All fish are mammals
All dogs are mammals

This argument DOES NOT show us that “All dogs are mammals” BECAUSE its not a sound argument, BECAUSE the premises are false. BUT, we are not basing the truth of the conclusion on this Argument. WE ALREADY KNEW B4 THE ARGUMENT THAT ALL DOGS ARE MAMMALS.

Thats the whole point. All we are saying is that arguments can be formed with false premises and make a conclusion we already knew about. The argument still is and always will be a bad argument. But since Technical Validity only deals with form, and the truth of the premises and conclusion does not play a role in how a conclusion “follows” from the premises, than it could turn out that a True conclusion follows from false premises. Here is the example again (We already know the conclusion is true):

All dogs are fish
All fish are mammals
All dogs are mammals

A valid argument, by mine and Kenneth’s defenitions. AND by Aporias defenition. So its 3 against 1 now. And by all 3 of our defenitions, Valid means only that the Conclusion follows from the premises. Not the Truth follows from the premises, only the inference. So we have a Valid argument, whose conclusion we know is true regardless of this argument, and we have 2 false premises. Thus the statement:

A true conclusion can follow from false premises.

Feel silly yet?

not at all…

-Imp

[size=150]I like milk and cookies. Anyone else?[/size]- Gamer

LET ME REPEAT:

“follows” means directly inferred from the premises."

NOW PAY ATTENTION!!!

NOW COMBINE THIS LAST STATEMENT WITH THIS ONE:

“Notice that the validity of the inference of a deductive argument is independent of the truth of its premises”

INFERENCE IS INDEPENDENT OF THE TRUTH OF THE PREMISES! SO BY YOUR OWN DEFENITION OF “FOLLOWS”, the truth of the premises has nothing to do with it!

Thank you.

“WE ALREADY KNEW B4 THE ARGUMENT THAT ALL DOGS ARE MAMMALS.”

you don’t have an inference. and you actually don’t even have an argument. you assumed the conclusion before the “argument”.

you have two unrelated statements that you claim are premises.
you do not infer anything from the premises because you have concluded the conclusion is true before the “argument” occurs… (this is another form of begging the question btw. a fallacy which renders your “argument” invalid)

-Imp

Now, Imp, just one more time:

Here is a completely different argument:

1. If Bill Gates had ten trillion dollars, then Gates would be rich. (Argree?)
2. But Bill Gates does not have ten trillion dollars. (Not even Bill Gates has that kind of money. So you would agree.)

Therefore, 3. Bill Gates is not rich. (But that is false. Bill Gates is the richest man in the world -or is supposed to be. But he certainly is rich.)

So, here we have another example of an argument, 1, 2. therefore, 3, which has true premises and a false conclusion.

But you said that if an argument has true premises, then it must have a true conclusion. So this argument, as well as the one I gave before, shows that it is false that if an argument has true premises, it must have a true conclusion, since it (and the other one, has true premises and a false conclusion)

When an argument has true premises and a false conclusion, then you know it must be an invalid argument, because a valid argument is defined as an argument which if it has true premises, it must also have a true conclusion.

If you think about it, you can easily see why the above argument is invalid (that is why the conclusion does not follow from the premises). The reason is that the first premise says the if Bill Gates has ten trillion dollars then he is rich. And that, of course, is true. But the first premise does NOT say that ONLY if Bill Gates has ten trillion dollars is he rich. Having ten trillion dollars is not the ONLY amount that would make a person rich. After all, having less than ten trillion would be enough to make someone rich, for example, having ten billion would certainly be enough. And, of course, having more than ten trillion dollars would be enough. It isn’t as if ONLY ten trillion dollars is the magic number.
Now the second premise tells us that Gates doesn’t have ten trillion dollars. But since, as I pointed out, the first premise does not say that ten trillion and ONLY ten trillion makes a person rich, then the conclusion, that Bill Gates is not rich can still be false, even if it is true that if Bill Gates has ten trillion he is rich, and even if it is true that Bill Gates does not have ten trillion.
So it is easy to see why it is that the Gates argument is invalid, and why it can have both its premises true, and the conclusion false. Anyone who believed the argument was valid would be thinking that the first premise “If Gates has ten trillion, then he is rich” meant, “ONLY if Gates has ten trillion is he rich” and, of course, that is not what “I Gates has ten trillion dollars, then Gates is rich” means.

By the way, I said above that we could know that the Gates argument was invalid, because it has true premises and a false conclusion. And that is right. But that should not be taken to mean that ONLY if an argument has true premises and a false conclusion is the argument invalid. Not at all! An argument may be invalid (the conclusion does not follow from the premises) when: the premises are true, and the conclusion false (as in the Gates argument), but also, if the premises are true and the conclusion is true; if the premises are false, and the conclusion, true; or the premises false and the conclusion false. In fact, any combination of premises and conclusion (whether they are true or false) can yield an invalid argument. But that is not, of course, true about valid arguments, for if a valid argument has true premises, then it MUST have a true conclusion.

If this doesn’t make everything clear, then nothing will.

Imp… All I can say is WOW…

“WE ALREADY KNEW B4 THE ARGUMENT THAT ALL DOGS ARE MAMMALS.”

you don’t have an inference. and you actually don’t even have an argument. you assumed the conclusion before the “argument”."

Its a pointless argument, but by defenition of an argument, we do have an argument. An argument is a series of propositions with a set of premises and a final conclusion. The argument does not need to prove a conclusion true to be an argument… Nor does it matter if the conclusion is already proven. It is still an argument. A pointless, waste of time argument, but an argument none-the-less. An argument can be good or bad. A good argument is usually valid in form, and the premises are true. The Oxford Companion to Philosophy also says an invalid argument can still be good if it supports the conclusion through non-deductive means, such as induction. But ofcourse you would refute that, but this is not the point.

“Follows” means to be infered from the premises. A FALSE CONLUSION CAN BE INFERED FROM FALSE PREMISES. Here is an example of the process of inference:

All ducks are named Impenitent
All things named Impenitent are Silly, Confused Philosophers
Thus, All ducks are Silly, Confused Philosophers.

Thats perfect inference. As was said millions of times because INFERENCE IS NOT DEPENDANT OF THE TRUTH OF THE PREMISES. Inference is a whole diffirent animal. An inference can be pointed out in arbitrary arguments. This shows that the TRUTH OF THE PREMISES DOES NOT MATTER. Example:

If A, Then B
A
Thus B

Thats a valid inference. NO MATTER WHAT A or B ARE. True, false, complete rubish or absolute law, IT DOESNT MATTER. By the rules of Inference, ANY B, EVEN IF ITS FALSE, CAN BE INFERED FROM THE INITIAL 2 PREMISES.

[size=150]“FOLLOWS” DOES NOT MEAN “IS MADE TRUE BY”

TRUTH PLAYS NO ROLE IN DETERMINING VALID INFERENCES AND DETERMINING IF A CONCLUSION “FOLLOWS” FROM THE PREMISES[/size]