## 45-1-25

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sdwarrior403

Posts: 114
Joined: Fri Aug 10, 2012 8:13 pm

### 45-1-25

Stimulus is:

V some E
E ---> ~KH
___________
V some ~KH

I agree that answer C does this. But doesn't B as well?

MS some SP
SP ---> D
___________
MS some D

ScottRiqui

Posts: 3633
Joined: Mon Nov 29, 2010 8:09 pm

### Re: 45-1-25

Shouldn't the first rule for answer B be: "SP some MS" instead?

Just as some Visitors Engage in harmful practices (V some E), some Petition Signers Support the Mayor (SP some MS).

I think C is more closely parallels the question, specifically the "no one who" construction of the second sentence. I'm going to keep looking at it though - there should be something that makes B more-explicitly "wrong".

timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

### Re: 45-1-25

The order of a some statement is irrelevant.

ScottRiqui

Posts: 3633
Joined: Mon Nov 29, 2010 8:09 pm

### Re: 45-1-25

timmydoeslsat wrote:The order of a some statement is irrelevant.
True, I was just thinking that answer B doesn't naturally parallel the question as well as OP's post made it seem.

Here's my English translation that fits both the question and answer C:

"Some of group A do B. If you do B, then you don't do C. Therefore, some of A don't do C"

For the question, 'A' is visitors, 'B' is engage in harmful activity, and 'C' is knowing that the activity is harmful.

For answer C, 'A' is poll respondents, 'B' is living out of town, and 'C' is voting.

For answer B, 'A' would be petition signers, and 'B' would be supporting the mayor. But what would 'C' have to be to complete the parallel structure? There's nothing to put for C that would make the "If you do B then you don't do C" part of the translation make sense.

Now, you can force the square peg into the hole by making 'A' the people who support the mayor and 'B' signing the petition. Then, 'C' would be "avoiding being denounced".

Now, the translation becomes "Some people who support the mayor signed the petition. If you signed the petition, then you don't avoid being denounced by the mayor. Therefore, some of the mayor's supporters don't avoid being denounced by the mayor.

Strictly speaking, that's what answer B says, but it's a torturous fit to the original question, compared to answer C.

boblawlob

Posts: 519
Joined: Mon Oct 11, 2010 7:29 pm

### Re: 45-1-25

B is wrong because for a transitive property conditional to work, the chain must go from Some/Most to All, not All to Some/Most.

Let's look at this example:

Some As are Bs.
All Cs are As.

AAAAAAAAAAAAA
CCC BB

If you combine try to combine the 2 statements so that it could say Some Cs are Bs, then it is wrong because look at the diagram above: no overlap with C or B

Now let's look at another example:

Some As are Cs.
All Cs are Ds.

AAAAAAAAAAA
CCCC
DDDD

If you combine the two statements, some As are Ds, and this is absolutely true.

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ScottRiqui

Posts: 3633
Joined: Mon Nov 29, 2010 8:09 pm

### Re: 45-1-25

I think answer 'B' *does* go from 'some' to 'all', though. Some of the petition signers were supporters of the mayor, and the mayor denounce all of the petition signers, therefore, some of the people she denounced must have been her supporters.

To use your notation, where A is the group of people the mayor denounced (the list of petition signers), B are people who support the mayor, and C are people who signed the petition but don't support the mayor (group C could have just as easily been omitted, though):

AAAAAAAAAAAAAA
BBBBBBBBBCCCCCCC

There's no way to denounce all of the petition signers without denouncing some people who support the mayor.

So while I still don't think that answer B parallels the question nearly as well as answer C, I don't think it's logically incorrect.

boblawlob

Posts: 519
Joined: Mon Oct 11, 2010 7:29 pm

### Re: 45-1-25

ScottRiqui wrote:I think answer 'B' *does* go from 'some' to 'all', though. Some of the petition signers were supporters of the mayor, and the mayor denounce all of the petition signers, therefore, some of the people she denounced must have been her supporters.
.
No, it doesn't.

Some PS -> MS
PS -> Denounced
Therefore Some Denounced -> MS

Here, the variable that both statements share are one the same side, and the conclusion is an inference not obtained via transitive property.

The stim is:
Some V -> HA
KHA -> Not HA (HA -> Not KHA)
Therefore Some V -> Not KHA.

Stim uses transitive property to reach conclusion where the shared variables in each statement are linked to form a chain.

You're right though: I think what happened was I diagrammed "Denouncing everyone who signed petition" as
Denounced -> SP when it was supposed to be SP -> Denounced, because mayor could have denounced many more people as well.

ScottRiqui

Posts: 3633
Joined: Mon Nov 29, 2010 8:09 pm

### Re: 45-1-25

Since 'some' statements can be correctly written in either direction, what if you had written answer B as:

Some MS -> PS
PS -> Denounced
Therefore some MS -> Denounced

That's clearly reaching the conclusion via a transitive operation.

Thanks for your explanation, BTW - it makes it clear why answer B isn't using the transitive property as written. But it appears to be logically equivalent to what I just wrote above, which does use a transitive operation to reach the conclusion.