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Hello,

(I had originally written Only in the topic title, I meant Unless.
So I do well on LR, but don't diagram, however I'd like to be able to understand how I'm supposed to do it.

For example, the blueprint website has an example of “Unless I just brushed my teeth, you’ll find me sipping a cold glass of orange juice”, and their diagram says

not JB —> OJ

Contrapositive:

not OJ —> JB

Now, I can memorize this and remember it this way. It also makes sense to me. However, what doesn't make sense to me is if these are the only two possibilities.

Is,

JB -> not OJ also correct, or no?

(If I've just brushed my teeth, then I'm not drinking OJ.)

I understand that you have to be careful and can't just go based on what makes "sense in the real world", but instead have to adhere to the actual statement in its absolute logic, so I'm wondering if I've fallen into this trap.

If my diagram does not work, I think I probably have the necessary and sufficient conditions mixed up, but that really isn't explanatory enough for me. Would someone please explain?

Thank you

dontsaywhatyoumean wrote:Hello,

So I do well on LR, but don't diagram, however I'd like to be able to understand how I'm supposed to do it.

For example, the blueprint website has an example of “Unless I just brushed my teeth, you’ll find me sipping a cold glass of orange juice”, and their diagram says

not JB —> OJ

Contrapositive:

not OJ —> JB

Now, I can memorize this and remember it this way. It also makes sense to me. However, what doesn't make sense to me is if these are the only two possibilities.

Is,

JB -> not OJ also correct, or no?

(If I've just brushed my teeth, then I'm not drinking OJ.)

I understand that you have to be careful and can't just go based on what makes "sense in the real world", but instead have to adhere to the actual statement in its absolute logic, so I'm wondering if I've fallen into this trap.

If my diagram does not work, I think I probably have the necessary and sufficient conditions mixed up, but that really isn't explanatory enough for me. Would someone please explain?

Thank you

Hey there! I too use Blueprint prep. And when we learned about the words unless, until, except and without, we learned that we need to replace those words with the words "if not". So in your example, “Unless I just brushed my teeth, you’ll find me sipping a cold glass of orange juice” it would be replaced with "If I did not just brush my teeth, you'll find me sipping a cold glass of orange juice.

So when you Diagram it, it says:

not JB --> OJ

and the contrapositive would be:

not OJ --> JB

and yes these are the only two possibilities. Both statements are to be taken as true and nothing else. (JB --> not OJ does not make sense because although it could be possible in the real world, according to the statement they gave you, it cannot be possible. The only information you have is that If I did not just brush my teeth, you will find me sipping a cold glass of orange juice, and the contrapositive of the statement (logically equivalent statement) If I did not find you sipping a cold glass of orange juice, then you just brushed your teeth.

Oh and you did diagram it right. Whatever statement follows the word "unless" becomes your sufficient condition which you also negate. I hope this somewhat helps. Just know you only have whatever you diagram plus its contrapostive! Goodluck

Whatever follows only is a necessary condition.

Did you mistake the question for an "Only" type question? Because the example you provided is an "Unless" question. Whatever follows the word "Only" becomes your necessary condition. "Only" can be tricky sometimes it is not always the first word that follows that becomes your necessary condition. You have to look for the referent of the statement. Only mondays are Kyles favorite day of the week. In this statement, Kyle is the referent of the statement so he becomes the necessary condtion. SO:

M-->KFD

NOT KFD --> NOT M

Hope this helps!

Oh sorry, I meant "Unless". No, I interpreted it as unless.

sephora_addict wrote: Oh and you did diagram it right. Whatever statement follows the word "unless" becomes your sufficient condtion which you also negate. I hope this somewhat helps. Just know you only have whatever you diagram plus its contrapostive! Goodluck

Well my diagram, the one I was wondering if I diagrammed it right, is the,

JB -> not OJ.

(If I've just brushed my teeth, then I'm not drinking OJ.)

Which I thought was probably wrong, and based on your posts, I'm guessing is?


Hmm... Actually, think of it now like a logic games "If not, or unless" it seems to make sense.

Thanks (although I'd still appreciate clarification on this question)

dontsaywhatyoumean wrote:

sephora_addict wrote: Oh and you did diagram it right. Whatever statement follows the word "unless" becomes your sufficient condtion which you also negate. I hope this somewhat helps. Just know you only have whatever you diagram plus its contrapostive! Goodluck

Well my diagram, the one I was wondering if I diagrammed it right, is the,

JB -> not OJ.

(If I've just brushed my teeth, then I'm not drinking OJ.)

Which I thought was probably wrong, and based on your posts, I'm guessing is?


Hmm... Actually, think of it now like a logic games "If not, or unless" it seems to make sense.

Thanks (although I'd still appreciate clarification on this question)

I hope someone can give you a better answer. Sorry I kinda suck at explaining things. But yes, JB --> not OJ is wrong. You will deal with these conditional statements in both LR and LG so remember the rules for both sections.

dontsaywhatyoumean wrote:Hello,

(I had originally written Only in the topic title, I meant Unless.
So I do well on LR, but don't diagram, however I'd like to be able to understand how I'm supposed to do it.

For example, the blueprint website has an example of “Unless I just brushed my teeth, you’ll find me sipping a cold glass of orange juice”, and their diagram says

not JB —> OJ

Contrapositive:

not OJ —> JB

Now, I can memorize this and remember it this way. It also makes sense to me. However, what doesn't make sense to me is if these are the only two possibilities.

Is,

JB -> not OJ also correct, or no?

(If I've just brushed my teeth, then I'm not drinking OJ.)

I understand that you have to be careful and can't just go based on what makes "sense in the real world", but instead have to adhere to the actual statement in its absolute logic, so I'm wondering if I've fallen into this trap.

If my diagram does not work, I think I probably have the necessary and sufficient conditions mixed up, but that really isn't explanatory enough for me. Would someone please explain?

Thank you

JB --> not OJ is not correct.

The easiest and simplest way for me to understand unless without etc questions has been to replace the word with "if not".

I will not go out unless joe does
I see as:
I will not go out if joe does not.

Both can be written:

not joe--> not go
or
go --> joe