need help with conditional logic

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jlhero

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Joined: Mon Feb 02, 2009 11:52 pm

need help with conditional logic

A should derive solely from B.

is this A if and only if B?

jamesireland

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Joined: Sun Dec 05, 2010 8:52 pm

Re: need help with conditional logic

I'd need some more context to understand what the original statement is getting at, but it doesn't seem that that alone translates to a biconditional. The original statement doesn't have the sort of symmetry that a biconditional statement has.

It might be something like: B -> A. This conditional indicates that one can derive A, so long as one has B already. What this doesn't capture is the "solely" part, which I want to say can't be captured without quantification.

TL/C;DR version: it's not A <-> B, it might be B -> A.

jlhero

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Joined: Mon Feb 02, 2009 11:52 pm

Re: need help with conditional logic

the original statement was something like:

the actual value of a jewelry should derive solely from its aesthetic value.

it is supposed to be a strengthening principle for something like this:

because a fake jewelry that is not identifiable by the naked eye does not differ in its aesthetic value from an authentic one, it should be deemed as valuable as the authentic jewelry.

jamesireland

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Joined: Sun Dec 05, 2010 8:52 pm

Re: need help with conditional logic

In that case there doesn't seem to be any conditional reasoning.

The bit about fake jewelry is making what should appear to be a pretty strong claim: fake jewelry should be deemed as valuable as actual jewelry. The reason given for this is that they do not differ in aesthetic value (which is also a strong claim, supported by the claim that they are indistinguishable to the naked eye).

Upon reading this you should have a strong reaction. You might think that even though a piece of fake jewelry and a piece of real jewelry have the same aesthetic value, this doesn't mean that they need to be deemed as valuable. Maybe the real jewelry is made of solid gold, and the fake jewelry is only gold plated, and so the real jewelry has much greater monetary value. This would make one think that (all else equal) the real jewelry should be deemed more valuable.

The statement is a strengthening principle because it eliminates problems like that just mentioned. According to it, it doesn't matter if the real and fake jewelry have different monetary values, all that matters is the jewelry's aesthetic value.

jlhero

Posts: 49
Joined: Mon Feb 02, 2009 11:52 pm

Re: need help with conditional logic

but i still think a relationship like A should derive solely from B contains conditional logic...

it may be B-->A or B<-->A

cogitoergosum

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Re: need help with conditional logic

I tend to think that if indeed it is a conditional statement it would be A --> B, not the opposite. I would read "A should derive solely from B" as "A only if B," which would make A a sufficient condition for B.

Anyone else?
Last edited by cogitoergosum on Wed Aug 31, 2011 9:26 pm, edited 1 time in total.

cogitoergosum

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Joined: Tue May 31, 2011 7:13 pm

Re: need help with conditional logic

The "should" is weird though, and seems to suggest something less concrete than a conditional statement...

kaiser

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Joined: Mon May 09, 2011 11:34 pm

Re: need help with conditional logic

"Should" is NOT a conditional statement.

/thread unless OP wishes to revise his hypothetical

jlhero

Posts: 49
Joined: Mon Feb 02, 2009 11:52 pm

Re: need help with conditional logic

i think ur right.

the word should made the relationship less strong, so this is a strengthener instead of an assumption.

now i have another question.

if the question assumes A-->B,

then is B-->A an strengthener for the question?

thank you guys!~~~

kaiser

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Joined: Mon May 09, 2011 11:34 pm

Re: need help with conditional logic

jlhero wrote:i think ur right.

the word should made the relationship less strong, so this is a strengthener instead of an assumption.

now i have another question.

if the question assumes A-->B,

then is B-->A an strengthener for the question?

thank you guys!~~~

No, "should" isn't even a strengthener. "Should" means nothing in this context. It means its one person's opinion of what the state of the world "should" ideally be given some other state of events. It carries no weight, and doesn't do anything to strengthen.

As for your new question, I have no clue what you mean by "a strengthener". If the question tells you that A-->B then you cannot deduce B-->A since B merely allows for the possibility of A occuring. B alone does not necessarily guarantee the occurrence of A (I say "not necessarily" because it theoretically could be the case that B does indeed lead to A, but we can't assume this on our own).

jlhero

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Joined: Mon Feb 02, 2009 11:52 pm

Re: need help with conditional logic

1. should + A-->B can strengthen a conclusion because it is a principle that makes the conclusion slightly more likely.

2. my second question is, if the conclusion of a stimulus conclude A-->B without giving a supporting premise, which means the stimulus contains an assumption of if A, then B. If the question asks which answer choice would strengthen the conclusion, would an answer choice saying B-->A strengthen the conclusion? (perhaps by making the assumption of A-->B slightly more likely to be true?)

kaiser

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Joined: Mon May 09, 2011 11:34 pm

Re: need help with conditional logic

jlhero wrote:1. should + A-->B can strengthen a conclusion because it is a principle that makes the conclusion slightly more likely.

2. my second question is, if the conclusion of a stimulus conclude A-->B without giving a supporting premise, which means the stimulus contains an assumption of if A, then B. If the question asks which answer choice would strengthen the conclusion, would an answer choice saying B-->A strengthen the conclusion? (perhaps by making the assumption of A-->B slightly more likely to be true?)

1. Completely incorrect. I don't know where you are getting that from, and I would like to know your source. "Should" is just an opinion. It says absolutely nothing about the state of the world. Many things are counterintuitive in real life, such that what "should" happen doesn't actually happen. Example:

In law school, I studied a lot so I should do well on the exam

Well guess what? What "should" happen isn't necessarily the correlation that exists in the real world (where amount of studying actually has little to do with how well you perform on law school exams). So my opinion that something "should" happen has zero effect on the strength of the correlation. And what kind of authority am I? "Should" is an opinion word so the authority comes into question, as opposed to a conditional which is deductive, and would be the case even if no person in the world existed (i.e. if it rains, the ground will be wet). So no, you are not correct about this. Again, please provide a source and I will certainly check it out.

2. Your Q is incomplete. No question gives you a conclusion absent any premise. And I've almost never seen a questino in which the conclusion itself is a conditional relationship (though its theoretically possible). Again, if you point me in the direction where you saw this odd example, I would be happy to look it up. I'm just going to stop you here because this hypo isn't reflective of what is on the test, and is only going to confuse people who will actually try and analyze it. If the conclusion were A-->B, then why would an assumption be if A then B? That is exactly what the conclusion is. And why are we talking about assumptions in the context of a strengthening question? Again, I think we all need to be on the same page before we analyze this because its only going to confuse people.

jlhero

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Joined: Mon Feb 02, 2009 11:52 pm

Re: need help with conditional logic

i don't know why you think we shouldn't talk about assumptions in strengthening questions. often the stimulus would contain a gap, which is assumed to be true for the conclusion to be properly drawn. often a strengthening answer (in the example i mentioned, a principle) would bridge that gap or make that assumption to be slightly more likely to be true (correct me if you think differently).

the principle strengthen question i am talking about i think it is from pt 62 (not 100% sure). It's about the aesthetic value of a jewel and whether a fake one unidentifiable by the naked eye would be deemed as valuable as a real one.

kaiser

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Joined: Mon May 09, 2011 11:34 pm

Re: need help with conditional logic

jlhero wrote:thank you for the reply.

i don't know why you think we shouldn't talk about assumptions in strengthening questions. often the stimulus would contain a gap, which is assumed to be true for the conclusion to be properly drawn. often a strengthening answer (in the example i mentioned, a principle) would bridge that gap or make that assumption to be slightly more likely to be true (correct me if you think differently).

the principle strengthen question i am talking about i think it is from pt 62 (not 100% sure). It's about the aesthetic value of a jewel and whether a fake one unidentifiable by the naked eye would be deemed as valuable as a real one.

Lets start from scratch and construct a hypo piece by piece. Again, I'm not saying you are wrong. I am just confused by what you are presenting (or perhaps its just how you are presenting it).

So what is your premise, what is the conclusion? Lets start with that. Then we can discuss what the assumption is that links the premise and the conclusion (and then finally determine what would strengthen). But we gotta do this step by step or else its just gonna go off the rails again. So what is the premise and the conclusion you want to propose for this hypo?