Q24 - Although all contemporary advertising

[georxia]

I'm confused why C is wrong. is it because it requires the contrapositive to reach the conclusion. Because both E and C use the logic chain with a "some" statement with a conditional statement.

[tommywallach]

Hey georxia,

With all match the reasoning questions, your first step is always to understand, as clearly as possible, the structure you are attempting to match.

Conclusion: Some attempts at persuasion are m.r.

Premise: All ads try to persuade, but only a small portion are m.r.

Notice how straightforward this argument is. There's no flaw/assumption. If we translated it into variables, it would say this

Conclusion: Some P are MR

Premise: All A are P, but only a few are MR.

Let's try to match!

(A) No X's are...Nope. This can't work, as it starts with a NO.

(B) Not all = some, so this could work. Some X are Y. So some X are Z. This is missing the third piece of the argument. Wrong!

(C) Premise: All M are GDM (good decision makers), some are not --> We already have a problem. The original argument had three separate variables in the premises, but this one only has two.

Conclusion: Some X are NOT Y --> Nope. Our conclusion is that some X's ARE Y.

(D) Direct correlation? That ain't right...

(E) Premise: All S are SP, some S are TP
Conclusion: Some SP = TP

Yep! Matches exactly!

Make sense? You can do the work by matching the pieces of the premise OR the pieces of the conclusion. (C) actually makes slight errors with both of them!

-t

[georxia]

But C does have three separate variables the only difference is one is a negative of the other:

1st premise: GM--->MIDBAD
2nd premise: M<--(s)-->~(MIDBAD)

Conclusion: M<--(s)-->~(GM)

The chain follows with the implicit contrapositive of GM-->MIDAB

[YT]

But C does have three separate variables the only difference is one is a negative of the other:

1st premise: GM--->MIDBAD
2nd premise: M<--(s)-->~(MIDBAD)

Conclusion: M<--(s)-->~(GM)

The chain follows with the implicit contrapositive of GM-->MIDAB

I 100% agree with your diagram. In order to reflect the form better, I'm using P, Q and R.

1st premise: P--->Q
2nd premise: R<--(s)-->~Q
Conclusion: R<--(s)-->~P

Stimulus:

1st premise: P--->Q
2nd premise: P<--(s)-->R
Conclusion: Q<--(s)-->R

(P: Contemporary advertising, Q: Attempts at persuasion, R: Morally reprehensible)

I think the problem with C is neither that it does not have three separate variable nor that it does a contrapositive. I think the issue is that its conclusion reflects a relation between P and R, meanwhile stimulus reflects one with Q and R.

Hope that helps.