Reasonable people adapt themselves to the world; unreasonable people persist in trying to adapt the world to themselv...

Alyona1983 February 1, 2018

"All" was confusing

I wanted to pick B, but was confused with "All" that should indicate Necessary condition. SO, if there is "all" inside of IF statement, IF is always stronger? Or just look at the common sense?

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Mehran February 4, 2018

Hey @AlyonaHess, thanks for your post. The word "all" denotes a sufficient condition, not a necessary condition.

Hope this helps. Please let us know if you have any additional questions.

Alyona1983 February 23, 2018

Mehran, typo!
In the answer B I was confused (and still is ) with ONLY, not "all". In B there is no "all";)

Only indicates necessary, right?
I diagrammed it:
Not Progress - > Rp
because it says " if there are only reasonable people".
How can we ignore it and diagram:
onlyRP - > Progress.
Please help.

hales June 30, 2019

@mehran, I have the same question as @AlyonaHess - I diagrammed B out with "only" functioning as a necessary indicator, not as "onlyRP." Could you further clarify how "only" functions within this question? Thanks.

Ravi June 30, 2019

@AlyonaHess and @hales,

Happy to help. Let's take a look.

Here's our diagram of the stimulus:

RP - >Adapt themselves to the world
UP - >Try to adapt world to themselves

Conclusion: Progress - >UP

Based on that, we're trying to find the answer choice that must be
true if all of those things are true.

(B) says, "If there are only reasonable people, there cannot be progress."

This is diagrammed as

RP - >No Progress

Progress - >/RP (UP) this is the same thing as what's being said in the
conclusion of the stimulus (Progress - >UP)

(B) is a contrapositive of the conclusion of the argument. If progress
requires unreasonable people, then it must be true that if there are
only reasonable people (meaning there aren't any unreasonable people),
then there wouldn't be any progress.

"If there are only" is telling us that there are no unreasonable
people in the world and is basically the same thing as saying "if all
people are reasonable," and this first part of the sentence is all in
the sufficient condition. "Cannot" tells us that the part immediately
after it is in the necessary condition and is negated. Thus, (B) is
the contrapositive of the last statement in the stimulus and must be
true if we assume everything in the stimulus to be true.

Does this make sense? Let us know if you have any more questions!