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certainly A is true...for a valid argument conclusion should be true while some premise can be true.Therefore for circular argument to be true the premise should be true as the truth for the conclusion is mandatory

I think VA Conclusion can be true only when all the premises are true. In a CA if all the premises are true then the conclusion is true and it is equal to VA. Hence A is correct.

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.

Look at the part in bold. I know logically it would mean that it is not possible for the conclusion to be false, but I thought it was a trick question and it mean that not all premises to be true AND conclusion must be false. Just thought the language was very awkward.

If that's the case, then u would read it as premise = false / conclusion = false for valid argument. The multiple choices confirmed that my interpretation is wrong, but wasted valuable time in figuring that out.

Can someone help me with this, I've been thinking about this for 15minutes and still can't figure it out. I can understand why A is correct. But why is D wrong?

Won't by definition if X the Circular = Valid then if !X then Circular != Valid.

Re: A valid argument is often defined as one in which it is not [#permalink]
20 Dec 2011, 03:14

A valid argument= it is not possible for all the premises to be true and the conclusion false. -- if all premise true then conclusion true -- if one among the many conclusion false then conclusion can be false -- if all false then conclusion false

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

so,

(A) Every circular argument is valid as long as its premises are true. Correct, for a circular arg. premise = conclusion, and this is possible when all the argument in Valid arg. are true. Hope this helps.

Re: A valid argument is often defined as one in which it is not [#permalink]
26 Dec 2011, 08:45

A and D are identical, As D states the some circular argument are valid ( for this to happen then premise of argument has to be true which is what option A is also suggesting.

Re: A valid argument is often defined as one in which it is not [#permalink]
27 Jul 2012, 10:12

I think, even if the conclusion is true is will not make the argument valid. It becomes valid when no all its premises are true and the conclusion is true.

What A says is based just on conclusion being true.

Re: A valid argument is often defined as one in which it is not [#permalink]
20 Dec 2013, 10:31

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Re: A valid argument is often defined as one in which it is not [#permalink]
22 Dec 2013, 00:37

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.

ARGUMENT SAYS THAT not possible for the conclusion TO BE false. IT MEANS THAT Conclusion has to be true....... Now in circular argument - one of the premises is identical to the conclusion. Hence, if the premise is true and identical to conclusion.....the conclusion is also true. This circular argument in which premise is true and conclusion true- is a valid argument as per definition above.....If other premises are also true( though not an essential requirement) the argument is still valid.

Only A correctly mentions this . Hence answer = A.

Re: A valid argument is often defined as one in which it is not [#permalink]
19 Apr 2014, 08:19

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

ARGUMENT SAYS THAT not possible for the conclusion TO BE false. IT MEANS THAT Conclusion has to be true....... Now in circular argument - one of the premises is identical to the conclusion. Hence, if the premise is true and identical to conclusion.....the conclusion is also true. This circular argument in which premise is true and conclusion true- is a valid argument as per definition above.....If other premises are also true( though not an essential requirement) the argument is still valid.

Only A correctly mentions this . Hence answer = A.

'If other premises are also true( though not an essential requirement) the argument is still valid' -- i don't understand how does an argument turn out to be valid when all other premises are also try since the question states 'it is not possible for all the premises to be true'.

Could you please shed some light on that?

gmatclubot

Re: A valid argument is often defined as one in which it is not
[#permalink]
19 Apr 2014, 08:19