Critical Reasoning

GMATGuruNY wrote: It is possible that these impurities came to be present in the iron many years AFTER the blades were produced.

GMATGuruNY wrote:If the contemporary sword maker and Damascus sword makers used iron from different sources, it is possible that Damascus sword makers did NOT use iron with these trace impurities but that these trace impurities came to be present in the blades LATER -- WEAKENING the conclusion that trace impurities in the iron are essential to the making of Damascus blades.

NOT able to relate the above TWO quotes.

If the FIRST is true then it leads to WEAKENING the conclusion that the trace impurities in the iron are essential to the making of Damascus blades, as mentioned in the SECOND quote.

Then, how/why we're considering that the FIRST quote is true ? SAME trace impurities as used by Contemporary sword maker should have been present in the historic Damascus swords at the time of producing the historic Damascus swords, I think ?

RBBmba@2014 wrote:

GMATGuruNY wrote: It is possible that these impurities came to be present in the iron many years AFTER the blades were produced.

GMATGuruNY wrote:If the contemporary sword maker and Damascus sword makers used iron from different sources, it is possible that Damascus sword makers did NOT use iron with these trace impurities but that these trace impurities came to be present in the blades LATER -- WEAKENING the conclusion that trace impurities in the iron are essential to the making of Damascus blades.

NOT able to relate the above TWO quotes.

If the FIRST is true then it leads to WEAKENING the conclusion that the trace impurities in the iron are essential to the making of Damascus blades, as mentioned in the SECOND quote.

Then, how/why we're considering that the FIRST quote is true ? SAME trace impurities as used by Contemporary sword maker should have been present in the historic Damascus swords at the time of producing the historic Damascus swords, I think ?

The first quote refers to an ASSUMPTION made in the passage.
To conclude that trace impurities are essential for the production of Damascus blades, IT MUST BE TRUE that the trace impurities present in historic Damascus blades were also present when the blades were PRODUCED.
If the portion in red is not true -- if trace impurities were introduced into the blades years AFTER the blades were produced -- then the argument cannot conclude that trace impurities are essential for the production of Damascus blades.
Thus, the portion in red constitutes an assumption.

Option B attacks this assumption by stating that the contemporary sword maker and Damascus sword makers obtained iron from different sources, implying that the trace impurities in the contemporary sword maker's iron might not have been present in the Damascus sword makers' iron but were introduced into the blades AFTER the blades were produced.

@Mitch - I get you here, except one confusion.

How this -- It is possible that these impurities came to be present in the iron many years AFTER the blades were produced -- COULD BE an ASSUMPTION made in the passage simultaneously when the statement in RED in your last quote is a MUST BE TRUE statement/ASSUMPTION itself ?

P.S: Can we really classify this CR as an CAUSAL ARGUMENT ? I think, it's a BIT unconventional in terms of CAUSAL ARGUMENT! Thoughts ?

Hi Mitch,
Any quick thoughts on the above Sir ?

Look forward to hear from you. Much thanks in advance!

Hi Mitch,
Any update on these doubts - https://www.beatthegmat.com/for-over-two ... tml#777168 ?

Could you please share your quick feedback on this Sir ? Much thanks in advance!

RBBmba@2014 wrote:@Mitch - I get you here, except one confusion.

How this -- It is possible that these impurities came to be present in the iron many years AFTER the blades were produced -- COULD BE an ASSUMPTION made in the passage simultaneously when the statement in RED in your last quote is a MUST BE TRUE statement/ASSUMPTION itself ?

I'm not quite sure what you're asking, but perhaps the following clarification will help:
In concluding that trace impurities are required to make Damascus blades, the argument above assumes that trace impurities were present in Damascus blades when the blades were produced.
If this assumption is true, then the conclusion of the argument holds.
If this assumption is not true, then the conclusion of the argument is invalidated.
It is not known whether this assumption is true.

Generally:
If an assumption is not true, then the conclusion of the argument is invalidated.
For this reason, we say the following:
An assumption is a statement that MUST BE TRUE for the conclusion of the argument to hold.

P.S: Can we really classify this CR as an CAUSAL ARGUMENT ? I think, it's a BIT unconventional in terms of CAUSAL ARGUMENT! Thoughts ?

The argument above is trying to establish a link between trace impurities in iron and the ability to make Damascus blades.
The correct answer choice must support this link.
Whether this link is classified as causal -- or as something else -- is irrelevant.

The conclusion is that the replication happened due to availability of a particular type of material.

In b, if the material was unknown at a certain time in history, there might be a chance that the material were available or discovered and used by others to replicate the blade.

Therefore the failed attempts could be due to the methodology of making the blade or some other reason, but not material. Therefore the methodology and not the material becomes essential for the making of blade.

Therefore, weaaking the conclusion.

Hope this logic is ok..

Hi Mitch,
I am afraid i cannot catch up the reasoning of RBBmba@2014.
Honestly speaking, i did picked up B, my reasoning is as following:

The conclusion is : trace impurities in the iron are essential for the production of Damascus blades.
My interpretation of "essential" is necessary, it is impossible to produce Damascus blades without trace impurities. in a short, no trace impurities, no production.

per answer choice B, The iron with which the contemporary sword maker made Damascus blades came from a source of iron that was unknown two centuries ago.
1) if B is true, the source was unknown two centuries ago, in other words, no source,
2) as the prompt says, no one had been able to make Damascus blades, in other words , no production.
based on 1) and 2), no source, no production.

Per answer choice D, Production of Damascus blades by sword makers of the past ceased abruptly after those sword makers' original source of iron became exhausted
it is also "no source, no production".

I know there is impossible have two answer choice on GMAT.
I known i am wrong, but i have no idea where is incorrect
Please help clarify,
Thanks in advance

Have a nice day
>_~

zoe wrote:Hi Mitch,
I am afraid i cannot catch up the reasoning of RBBmba@2014.
Honestly speaking, i did picked up B, my reasoning is as following:

The conclusion is : trace impurities in the iron are essential for the production of Damascus blades.
My interpretation of "essential" is necessary, it is impossible to produce Damascus blades without trace impurities. in a short, no trace impurities, no production.

per answer choice B, The iron with which the contemporary sword maker made Damascus blades came from a source of iron that was unknown two centuries ago.
1) if B is true, the source was unknown two centuries ago, in other words, no source,
2) as the prompt says, no one had been able to make Damascus blades, in other words , no production.
based on 1) and 2), no source, no production.

B does not imply that there was no production of Damascus blades.
B: The iron with which the contemporary sword maker made Damascus blades came from a source of iron that was unknown two centuries ago.
Here, the iron used by the contemporary sword maker was unknown to Damascus sword makers, implying that Damascus sword makers used a DIFFERENT iron to produce their blades.
As a result, this option WEAKENS the conclusion that the iron used by the contemporary sword maker is essential to the production of Damascus blades.
Eliminate B.