A b/c B question ...

[Giovanni.Nagao]

On the LSAT, when you are told "A b/c B" can you assume

a) If A → B
b) If B →A
c) Neither a) or b)

I’ve always suspected b) but I have never had it confirmed and if it isn’t b) I would certainly like to disabuse myself of the concept ...

[ohthatpatrick]

Well, hopefully I'm not leading you astray based on the overly symbolic, general nature of the question, but I think you are correct in saying that (B) is applicable.

Words such as "because", "since", "after all", and "for" are used as premise cues. A phrase that is prefaced by one of those premise cues indicates that the phrase that follows is a premise. Whatever idea that phrase supports, therefore, would be a conclusion based on that supporting premise.

For example:
You should date Kelly because she's funny.

Conc: You should date Kelly
Prem: Kelly is funny

This would be the same argument if I had otherwise written:
Because Kelly is funny, you should date her.

The way you're symbolizing that with option (B) is
Kelly is funny ---> You should date her

That's how we would represent the Argument Core, but just keep in mind that the arrow in the Core is not the same as the conditional arrow.

What we're really saying with the Core illustration is "DOES the conclusion follow from the evidence?"

So you can think of the Core of that argument being:
Kelly is funny ---?--> You should date her

We can read the Core as, "IF I accept that Kelly is funny, does that mean I HAVE TO ACCEPT that you should date her?"

The sufficient assumption that would make this argument airtight would be:
If Kelly is funny, then you should date her.

THAT is a conditional claim, and that arrow would be a definite connection between trigger and consequence.

So hopefully I haven't made this more confusing in my response. You are correct that "because", no matter where it appears in a sentence, indicates you are about to hear a premise, and premise ideas go on the left hand side of our Core diagram. The idea that is being supported by the "because" is a conclusion (either the main conclusion or a subsidiary conclusion). Conclusions go on the right hand side of our Core diagram.

Let me know if you have lingering questions.

[Giovanni.Nagao]

Patrick,

sorry, I thought the symbolization was clear ... the word 'if' and the arrow '→' were meant to symbolize a conditional relationship, so written out a) would read 'if A, then B' and b) would read 'if B, then A' ... thank you for giving me a chance to clear up any potential confusion ... i guess the verdict is still out on the original question ...

[ohthatpatrick]

Hey-o. I knew what you meant by "if" and "-->". I guess my response was muddled.

The answer to the original question is that (B) is correct, in a limited sense.

The sense in which (B) is correct is that we represent the argument core as [Prem --> Conc ] and "A b/c B" often means that B is the Premise and A is the conclusion.

For example:
We should vote the mayor out of office because he's behaving corruptly.

Argument Core:
Mayor behaving corruptly --> should vote him out

The sense in which (B) is NOT correct, though, is that the Core is not really a conditional statement.

It is not correct to say that any time you read something of an "A because of B" nature that you could interpret that to mean: If A, then B.

If the sentence is saying "A happened because of B", then we're getting a relationship of causality. (not conditional logic)

For example:
Bob got into an accident because he was texting while driving.

That is really just a statement of causality. Texting while driving caused Bob's accident.

That doesn't mean that we can say:
If Bob texts, he will get into an accident.

or even the past tense:
If Bob was texting, then he got into an accident.

If we're saying that "A is true because of B", then we're getting a statement of evidence to justify a claim. (not conditional logic) The mayor example from before was of this nature.

If you're arguing that "A is true" on the basis of "B", then you would represent your argument core as:
B -----> A
prem conc

But the arrow of the argument core is not a conditional arrow (which says that whenever the left side is true, the right side must follow). The author WANTS to believe that his evidence guarantees his conclusion, but we read mostly flawed arguments, so we know that this is normally not true: the author's evidence normally DOES NOT logically entail the conclusion.

So the arrow in the argument core is different from the arrow of conditional logic. If I'm looking at a conditional relationship, I know I can fully trust it to have no exceptions.

If I'm looking at an argument core, I know there's still something "iffy" about going from the left side idea to the right side idea.

That's why I was suggesting we could write the argument core's arrow as ---?-->

The question mark is to remind ourselves that this relationship is what the author is trying to sell us, not something we know to be true.

Again, let me know if any of this is fuzzy.

[Giovanni.Nagao]

Thank you Patrick ... your last message was a lot clearer (at least for me) : ) Thank you for your time and patience ...