Critical Reasoning

RBBmba@2014 wrote:

GMATGuruNY wrote: Why are the pre-1930 hotels that the guidebook writer visited still standing?
Because of their superior construction.
This is how you are attempting to interpret D.
But the conclusion is not about the hotels that the writer VISITED.
The conclusion is about ALL carpenters who worked on pre-1930 hotels.

OK. So, in the conclusion as it's NOT EXPLCITLY mentioned that writer is ONLY talking about hotels that he/she visited, we'd have to CONSIDER ALL pre-1930 hotels IN GENERAL. Right ?

And,GENERALLY, ( in any CR questions) if there is NO EXPLICIT information of any SPECIFICS like above, then we should ALWAYS consider that particular stuff as a whole IN GENERAL. Correct me please if wrong!

We we analyze a CR, we must not narrow or broaden the scope of the premise or conclusion.
In the CR above:
The premise concerns ONLY hotels that the writer has VISITED and ONLY carpentry that he has NOTICED.
The conclusion concerns ALL carpenters working on hotels before 1930 and ALL carpenters who have worked on hotels built subsequently.
That the conclusion is much broader in scope than the premise constitutes a major flaw in the argument.

Hi Mitch - yes, I absolutely understand your POINT...but could you please clarify whether I'm correct or not on my TWO questions above ?

It'd be MUCH helpful to identify this FLAW -- "That the conclusion is much broader in scope than the premise constitutes a major flaw in the argument"

Look forward to your feedback.Much thanks in advance!

Hi Mitch - could you please share your feedback to clarify my TWO concerns above ?

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

According to the OG explanation, "if there is some reason to think that hotels with good carpentry survive longer than those with bad carpentry, then still-existing hotels from the older era will have disproportionately more good carpentry, even assuming no difference between the skill, care, and effort of the carpenters from the two eras".

Is there reason to think that buildings post 1930 survived better than buildings before 1930?
If yes, how can it be justified? Clearly, there could not have been a sudden increase in the survival rate of buildings post 1930.

If no, how can the reasoning given above (the official explanation) be justified?

RBBmba@2014 wrote:Hi Mitch - yes, I absolutely understand your POINT...but could you please clarify whether I'm correct or not on my TWO questions above ?

Your understanding seems to be correct in both cases.

It'd be MUCH helpful to identify this FLAW -- "That the conclusion is much broader in scope than the premise constitutes a major flaw in the argument"

The premise is about a subset of a larger group: of all pre-1930 hotels, the ones still in existence.
The conclusion is about the entire group: all pre-1930 hotels.
It is a flaw to assume that what is true for the subset will be true for the entire group.

TheGraduate wrote:According to the OG explanation, "if there is some reason to think that hotels with good carpentry survive longer than those with bad carpentry, then still-existing hotels from the older era will have disproportionately more good carpentry, even assuming no difference between the skill, care, and effort of the carpenters from the two eras".

Is there reason to think that buildings post 1930 survived better than buildings before 1930?
If yes, how can it be justified? Clearly, there could not have been a sudden increase in the survival rate of buildings post 1930.

If no, how can the reasoning given above (the official explanation) be justified?

Here, to survive means to continue to exist.
Thus, the OE implies the following:
If there is some reason to think that hotels with good carpentry continue to exist longer than those with bad carpentry, then still-existing hotels from the older era will have disproportionately more good carpentry.
In other words, still-existing hotels from the older era have disproportionately superior carpentry because pre-1930 hotels with inferior carpentry have probably been torn down and thus do NOT continue to exist.

GMATGuruNY wrote: Here, to survive means to continue to exist.
Thus, the OE implies the following:
If there is some reason to think that hotels with good carpentry continue to exist longer than those with bad carpentry, then still-existing hotels from the older era will have disproportionately more good carpentry.
In other words, still-existing hotels from the older era have disproportionately superior carpentry because pre-1930 hotels with inferior carpentry have probably been torn down and thus do NOT continue to exist.

Hi Mitch. Thanks for your explanation.

I get the idea of survival.

Also, if a pre-1930 building with good carpentry is not torn down while one with bad carpentry is torn down, we are left with a high proportion of pre-1930 buildings.
On the contrary, post 1930, building does not fall into disuse and is not torn down even if it does not have good carpentry, leaving us with a more original mix of buildings of the post 1930 period.
That finally leaves us with a high proportion of pre-1930 buildings with good carpentry and lower proportion of post 1930 buildings with good carpentry. The situation presents the guidebook writer the illusion that there is more pre-1930 buildings with good carpentry.

However, what I'm not clear on is why the OE considers a sudden change in the survival of buildings post 1930. To me it appears the explanation entails a deduction that involves a change in the survival of buildings in the two periods.

Could you please clarify?

TheGraduate wrote:However, what I'm not clear on is why the OE considers a sudden change in the survival of buildings post 1930.

The OE does not discuss the survival rate of hotels built after 1930.

GMATGuruNY wrote:

TheGraduate wrote:However, what I'm not clear on is why the OE considers a sudden change in the survival of buildings post 1930.

The OE does not discuss the survival rate of hotels built after 1930.

But the pre1930 survival rate can be inferred to be different from post 1930. Why the difference?
Or am I missing something?

TheGraduate wrote:

GMATGuruNY wrote:

TheGraduate wrote:However, what I'm not clear on is why the OE considers a sudden change in the survival of buildings post 1930.

The OE does not discuss the survival rate of hotels built after 1930.

But the pre1930 survival rate can be inferred to be different from post 1930. Why the difference?
Or am I missing something?

Neither the passage nor the OE is concerned with the survival rate of new hotels.
Common sense tells us that new hotels continue to exist simply because they are NEW -- whether they have good carpentry or bad.
Only a hotel that is OLD is likely to fall into disuse and as a result be demolished.
Since only old hotels are likely to be torn down, the issue of survival is constrained to pre-1930 hotels.