PT89.S2.Q22 - Merle's argument

Ashley2018-1

So I just don't see how this stimulus is flawed
From the conditional statement: squeaking sound---> machine turned on, why can't we conclude that if the machine usually makes a squeaking sound, the machine is not usually turned on?
And what are the differences between D and E?

Admin Note: https://7sage.com/lsat_explanations/lsat-89-section-2-question-22/

canihazJD

The flaw is a change in domain from subset (just times when you get change) to superset (anytime)

When I get change the machine usually squeaks (just times when you get change)
If it squeaks then its on
so the machine is usually on. (anytime)

When I drive my car it usually produces exhaust (just times when I'm driving)
to produce exhaust my car must be running
so my car is usually running. (anytime)

D. changes from subset (people who read the novel) to superset (all people).

Most people who read the novel found it disturbing
if it disturbs you you have a vivid imagination
so most people have a vivid imagination

E. changes from the subset of (people who read the novel) to another subset (people with vivid imaginations)

Most people who read the novel found it disturbing
if it disturbs you you have a vivid imagination
So most people with vivid imaginations find the plot disturbing.

Ashley2018-1

Is E wrong because it is a reversal of a most statement, and that didn't show up in the stimulus?

canihazJD

It's wrong because it goes from talking about (people who read the novel) to (people who have a vivid imagination), instead of (all people) like D. It is flawed but in a different way - shifts from subset to subset.

Ashley2018-1

E.) read new horror novel---m--- disturbing
disturb-----> vivid imagination
vivid imagination ---m--- disturbing
Yeah, isn't this an illegal reversal of a most statement? is this diagrammed correctly?
the correct conclusion is supposed to be the reverse right? disturbing---m--- vivid imagination

canihazJD

@"ashley.tien" said:
E.) read new horror novel---m--- disturbing
disturb-----> vivid imagination
vivid imagination ---m--- disturbing
Yeah, isn't this an illegal reversal of a most statement? is this diagrammed correctly?
the correct conclusion is supposed to be the reverse right? disturbing---m--- vivid imagination

Translation is fine, but the conclusion you can draw is that most people who read the novel have a vivid imagination.

read new horror novel --m→ disturbing
disturb → vivid imagination
vivid imagination --m→ disturbing
read new horror novel --m→ vivid imagination

This would be an ok argument, but still wrong because it does not match the stimulus.

the correct conclusion is supposed to be the reverse right? disturbing---m--- vivid imagination

The second premise already gives us disturb → vivid imagination