Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

A valid argument is often defined as one in which it is not [#permalink]

Show Tags

28 Jun 2008, 23:38

2

This post received KUDOS

19

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

95% (hard)

Question Stats:

34% (02:25) correct
66% (01:30) wrong based on 988 sessions

HideShow timer Statistics

A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false. A circular argument is sometimes defined as one in which one of the premises is identical to the conclusion.

From these definitions we can infer that...

(A) Every circular argument is valid as long as its premises are true. (B) Every valid argument is circular. (C) No circular argument is valid. (D) Some circular arguments are valid, and some are not. (E) Some circular arguments are not valid, and some valid arguments are not circular.

Few Premises are valid and few are not within Valid arguments(VA). But conclusion is valid(not false). in circular argument(CA) one of the premise is identical with conclusion. Therefore, CA with one valid premise(identical) is a valid VA and some CA without identical premise is invalid VA. Hence D.
_________________

If You're Not Living On The Edge, You're Taking Up Too Much Space

A circular argument is sometimes defined as one in which one of the premises is identical to the conclusion.

So, in a circular argument, if the premises are all true, the conclusion must be true: the conclusion is the same as one of the premises.

durgesh79 wrote:

A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false.

Since the conclusion of a circular argument is the same as one of the premises, if the premises are all true, the conclusion cannot be false. Thus, circular arguments are 'valid arguments', according to the definitions. A.
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

A circular argument is sometimes defined as one in which one of the premises is identical to the conclusion.

So, in a circular argument, if the premises are all true, the conclusion must be true: the conclusion is the same as one of the premises.

durgesh79 wrote:

A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false.

Since the conclusion of a circular argument is the same as one of the premises, if the premises are all true, the conclusion cannot be false. Thus, circular arguments are 'valid arguments', according to the definitions. A.

A circular argument is sometimes defined as one in which one of the premises is identical to the conclusion.

So, in a circular argument, if the premises are all true, the conclusion must be true: the conclusion is the same as one of the premises.

durgesh79 wrote: A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false.

Since the conclusion of a circular argument is the same as one of the premises, if the premises are all true, the conclusion cannot be false. Thus, circular arguments are 'valid arguments', according to the definitions. A.

durgesh79 wrote:

A circular argument is sometimes defined as one in which one of the premises is identical to the conclusion.

So, in a circular argument, if the premises are all true, the conclusion must be true: the conclusion is the same as one of the premises.

durgesh79 wrote:

A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false.

Since the conclusion of a circular argument is the same as one of the premises, if the premises are all true, the conclusion cannot be false. Thus, circular arguments are 'valid arguments', according to the definitions. A.

Hi,

Shouldn't the above explanation also make option D right. ? D. Some circular arguments are valid, and some are not.

A circular argument is sometimes defined as one in which one of the premises is identical to the conclusion.

So, in a circular argument, if the premises are all true, the conclusion must be true: the conclusion is the same as one of the premises.

durgesh79 wrote: A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false.

Since the conclusion of a circular argument is the same as one of the premises, if the premises are all true, the conclusion cannot be false. Thus, circular arguments are 'valid arguments', according to the definitions. A.

durgesh79 wrote:

A circular argument is sometimes defined as one in which one of the premises is identical to the conclusion.

So, in a circular argument, if the premises are all true, the conclusion must be true: the conclusion is the same as one of the premises.

durgesh79 wrote:

A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false.

Since the conclusion of a circular argument is the same as one of the premises, if the premises are all true, the conclusion cannot be false. Thus, circular arguments are 'valid arguments', according to the definitions. A.

Hi,

Shouldn't the above explanation also make option D right. ? D. Some circular arguments are valid, and some are not.

I think D is wrong due to the expression of "some (CA) are not (valid)". CA is premise = conclusioin. It should be valid since, under CA, if premise is true, conclusion is to be true, if p is not true, then conclusion is not true. Any other thoughts?

From the question, "A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false." There is nothing in this definition to suggest that false premises make an argument invalid.
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Last edited by IanStewart on 29 Jun 2008, 13:42, edited 1 time in total.

There are only 2 values that the premise and conclusions can take. True and False. Thus the question states that

A valid argument is often defined as one in which it is not possible for all the premises to be true and the conclusion false

from this we can infer that if one of the premises is not true(= false) then the conclusion cannot be true (for a valid argument that is!!)

That is not a valid inference. While the question doesn't say that there are only two values the premise and conclusion can take, it doesn't make a difference if we assume this to be the case. An argument is valid if:

If the premises are true, the conclusion is true.

The lone inference we can make from this is the contrapositive (from "If A then B" you can always conclude "If not B then not A"). That is, we can conclude:

If the conclusion is false, the premises are false (well, at least one of them is).

The inference you have made, "If the premises are false, the conclusion is false", is called the 'inverse'. That is, you've translated "If A then B" into "If not A then not B". This is not a legitimate inference to draw, as I will illustrate with an example. Suppose I'm standing next to a swimming pool, and have no shelter nearby. Then the following may be true:

"If it rains, I get wet."

We can certainly deduce the contrapositive:

"If I'm not wet, it's not raining."

We cannot conclude the inverse:

"If it's not raining, I'm not wet". I might be in the swimming pool.

Equivalently, we cannot deduce the converse (I say equivalently, because the converse is the contrapositive of the inverse- they're logically the same):

"If I'm wet, it's raining." Again, I might be swimming.
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Premise 1 : The woman says she is not mad Premise 2 : Whatever the woman says is true Conclusion : The woman is not mad. (= premise 1)

more like A-->B-->C-->A

Anyone who rejects the argument’s conclusion should also reject at least one of its premises (the one that is the same as its conclusion), and so should reject the argument as a whole.

Anyone who accepts all of the argument’s premises already accepts the argument’s conclusion, so can’t be said to have been persuaded by the argument. In neither case, then, will the argument be successful.

Good discussion Guys, the OA is A. Below is the OE, which i dint understand.

"(A) Some people find this paradoxical, but it follows directly that circular arguments are valid. If the premises are true, and the conclusion is one if the premises, it must be true. Another trick here is the word 'valid'. Just because an argument is valid, does not mean it is true. Many people will make that false assumption and be thrown off on this question."

took long time to understand this. But agree with A.

Valid argument --> Often, all premises cannot be true, conclusion cannot be false Circular argument --> sometimes, premise = conclusion

(A) Every circular argument is valid as long as its premises are true.

If premises are true --> conclusion is true (Circular argument) --> and conclusion cannot be false in valid argument --> In this case, conclusion is true and hence circular argument is valid as long as its premises are true.

Its been long time coming. I have always been passionate about poetry. It’s my way of expressing my feelings and emotions. And i feel a person can convey...

Written by Scottish historian Niall Ferguson , the book is subtitled “A Financial History of the World”. There is also a long documentary of the same name that the...

Post-MBA I became very intrigued by how senior leaders navigated their career progression. It was also at this time that I realized I learned nothing about this during my...