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I read through the LRB bible section, and I realize that these can be done using formal logic, however I am still missing so many of them in the cambridge packet. I don't know if I'm just diagramming incorrectly with my logic or what, but I am getting really frustrated. If someone who is good at these could chime in that would be great.

flash21 wrote:I read through the LRB bible section, and I realize that these can be done using formal logic, however I am still missing so many of them in the cambridge packet. I don't know if I'm just diagramming incorrectly with my logic or what, but I am getting really frustrated. If someone who is good at these could chime in that would be great.

Maybe you're relying too much on diagramming. Most are probably most efficiently done w/o diagramming.

Perhaps try identifying the gap and saying it in words.

Clicked cause I thought this was going to be about OCI interviews

Manhattan LSAT Noah wrote:

flash21 wrote:I read through the LRB bible section, and I realize that these can be done using formal logic, however I am still missing so many of them in the cambridge packet. I don't know if I'm just diagramming incorrectly with my logic or what, but I am getting really frustrated. If someone who is good at these could chime in that would be great.

Maybe you're relying too much on diagramming. Most are probably most efficiently done w/o diagramming.

Perhaps try identifying the gap and saying it in words.

Thanks, maybe you are right. I will try this instead, as in, identifying the jump that is made to the conclusion?

flash21 wrote:

Manhattan LSAT Noah wrote:

flash21 wrote:I read through the LRB bible section, and I realize that these can be done using formal logic, however I am still missing so many of them in the cambridge packet. I don't know if I'm just diagramming incorrectly with my logic or what, but I am getting really frustrated. If someone who is good at these could chime in that would be great.

Maybe you're relying too much on diagramming. Most are probably most efficiently done w/o diagramming.

Perhaps try identifying the gap and saying it in words.

Thanks, maybe you are right. I will try this instead, as in, identifying the jump that is made to the conclusion?

Exactly. Often these are quite predictable, so work that skill for a while over diagramming. That said, I do bust out diagrams for SA questions with LOTS of conditional statements.

By SA im assuming you mean sufficient assumption, and if this is the case manhattan uses a pretty good example to diagram and I always resort back to this (the situation may not be exactly this but youll get the point:

If the situation was you wanted to buy a ball with strictly the money in your wallet, and the ball cost $50:
1. A necessary assumpton would be you would have $1 in your wallet to buy the ball. You MUST necessarily have 1 dollar to buy the ball, but the 1 dollar does not sufficiently satisfy the condition. If this is diagramed as a hollow conditional arrow, think of this situation as filling in part of the conditional arrow.
2. A sufficient assumption would be you have $100 in your wallet to buy the ball. You have a sufficient amoutn of money to buy the ball, but $100 is NOT necessary to bull the ball. You satisfy what is needed, but you do not necessarily have to hae $100 to buy the ball. If this sitatuation is diagramed as a hollow conditional arrow, think of this situation as filling in more that just the arrow and coloring outside the lines.
3. A necessary and sufficient assumption would be you have exactly $50 in your wallet to buy the ball. This number is not only required, but it is enough to fully satisfy the condition. This conditional arrow diagram fully colors in the hollow arrow.

In whole dollars:
1. Any amount from $1-49 is necessary
2. Any amount from $51+ is sufficient
3. $50 exactly is both necessary and sufficient

Idk if this is what you were even asking, but hope this helps

goldenboy514 wrote:By SA im assuming you mean sufficient assumption, and if this is the case manhattan uses a pretty good example to diagram and I always resort back to this (the situation may not be exactly this but youll get the point:

If the situation was you wanted to buy a ball with strictly the money in your wallet, and the ball cost $50:
1. A necessary assumpton would be you would have $1 in your wallet to buy the ball. You MUST necessarily have 1 dollar to buy the ball, but the 1 dollar does not sufficiently satisfy the condition. If this is diagramed as a hollow conditional arrow, think of this situation as filling in part of the conditional arrow.
2. A sufficient assumption would be you have $100 in your wallet to buy the ball. You have a sufficient amoutn of money to buy the ball, but $100 is NOT necessary to bull the ball. You satisfy what is needed, but you do not necessarily have to hae $100 to buy the ball. If this sitatuation is diagramed as a hollow conditional arrow, think of this situation as filling in more that just the arrow and coloring outside the lines.
3. A necessary and sufficient assumption would be you have exactly $50 in your wallet to buy the ball. This number is not only required, but it is enough to fully satisfy the condition. This conditional arrow diagram fully colors in the hollow arrow.

In whole dollars:
1. Any amount from $1-49 is necessary
2. Any amount from $51+ is sufficient
3. $50 exactly is both necessary and sufficient

Idk if this is what you were even asking, but hope this helps

Pretty spot on, but I have an issue with how you characterized the jointly necessary and sufficient assumption. If you word it as 'x has exactly $50 in his wallet', then that's a sufficient assumption, but it's not necessary. After all, if you negate the assumption, then he doesn't have exactly $50, but he doesn't need exactly $50 - he could have exactly $60. Now, you might've meant the following but just didn't explicitly put it this way: the necessary & sufficient assumption is that 'x has at least $50 in his wallet'. If you negate that, then he doesn't have at least $50, and so how can he buy the $50 ball? He must have at least $50 or else he simply can't afford it. But if he doesn't have exactly $50? What of it? It's sufficient to assume that he's got exactly $50, since it's enough to buy the ball, but conceivably he could have exactly $60 and that would allow the conclusion to follow too.

manhattan LR vs lsat trainer for LR? what do you guys think?

And thank you guys very much for the replies, it helped a lot.

goldenboy514 wrote:By SA im assuming you mean sufficient assumption, and if this is the case manhattan uses a pretty good example to diagram and I always resort back to this (the situation may not be exactly this but youll get the point:

If the situation was you wanted to buy a ball with strictly the money in your wallet, and the ball cost $50:
1. A necessary assumpton would be you would have $1 in your wallet to buy the ball. You MUST necessarily have 1 dollar to buy the ball, but the 1 dollar does not sufficiently satisfy the condition. If this is diagramed as a hollow conditional arrow, think of this situation as filling in part of the conditional arrow.
2. A sufficient assumption would be you have $100 in your wallet to buy the ball. You have a sufficient amoutn of money to buy the ball, but $100 is NOT necessary to bull the ball. You satisfy what is needed, but you do not necessarily have to hae $100 to buy the ball. If this sitatuation is diagramed as a hollow conditional arrow, think of this situation as filling in more that just the arrow and coloring outside the lines.
3. A necessary and sufficient assumption would be you have exactly $50 in your wallet to buy the ball. This number is not only required, but it is enough to fully satisfy the condition. This conditional arrow diagram fully colors in the hollow arrow.

In whole dollars:
1. Any amount from $1-49 is necessary
2. Any amount from $51+ is sufficient
3. $50 exactly is both necessary and sufficient

Idk if this is what you were even asking, but hope this helps

so are you saying the necessary assumption is something that is absolutely necessary for you to have, and without it you simply could not have the ball? but the sufficient assumption is more than satisfying the condition?

goldenboy514 wrote:By SA im assuming you mean sufficient assumption, and if this is the case manhattan uses a pretty good example to diagram and I always resort back to this (the situation may not be exactly this but youll get the point:

If the situation was you wanted to buy a ball with strictly the money in your wallet, and the ball cost $50:
1. A necessary assumpton would be you would have $1 in your wallet to buy the ball. You MUST necessarily have 1 dollar to buy the ball, but the 1 dollar does not sufficiently satisfy the condition. If this is diagramed as a hollow conditional arrow, think of this situation as filling in part of the conditional arrow.
2. A sufficient assumption would be you have $100 in your wallet to buy the ball. You have a sufficient amoutn of money to buy the ball, but $100 is NOT necessary to bull the ball. You satisfy what is needed, but you do not necessarily have to hae $100 to buy the ball. If this sitatuation is diagramed as a hollow conditional arrow, think of this situation as filling in more that just the arrow and coloring outside the lines.
3. A necessary and sufficient assumption would be you have exactly $50 in your wallet to buy the ball. This number is not only required, but it is enough to fully satisfy the condition. This conditional arrow diagram fully colors in the hollow arrow.

In whole dollars:
1. Any amount from $1-49 is necessary
2. Any amount from $51+ is sufficient
3. $50 exactly is both necessary and sufficient

Idk if this is what you were even asking, but hope this helps

This is almost exactly the same example I use in my tutoring to illustrate these concepts! (Have I tutored you before?)

exactly...as otunga pointed out, saying you have EXACTLY 50 is not a necessary assumption. i should have kept the word exactly out, but I meant to show that stating 50 dollars is both necessary and sufficient.
a necessary condition is something that is in fact necessary, and without the necessary condition, it is false. If you want enough money to buy the ball, than you need $50. If you have 50, than you surely have 1 dollar. So having 1 dollar is necessary to buy the ball. IF YOU NEGATE THE NECESSARY, than it sohuld destroy the argument. Not having 1 dollar destroys the argument because if you do not have $1, than you do not have 1, 2, 5, 25, 49, 50, or a million dollars.

The sufficient does not mean that you have more than what is needed. it means you have enough to satisfy the condition ($50), but could potentially have more than what is needed. to say having $60 is sufficient would be correct, but it is not necessary. It is rather necessary to have 1-50 dollars. Having 50+ is sufficient. And having 50 dollars would both satisfy the necessary, and would be sufficient to buy the ball.

By negating the necessary, you are destroying the logic. But when you negate the sufficient, it doesnt mean you are destroying the logic. (you could be however if you are negating both the sufficient and necessary simultaneously)

Nessary negated: You DONT have 1 dollar. Well than you sure as hell dont have $50, so you aint gettin that ball!
Sufficient negated: You DONT have $100. Sorry im not rich, but i still could have $99, or even $51, so I still may have enough to buy the ball. Negating the sufficient doesnt destroy the argument.

LSAT Blog wrote:

goldenboy514 wrote:By SA im assuming you mean sufficient assumption, and if this is the case manhattan uses a pretty good example to diagram and I always resort back to this (the situation may not be exactly this but youll get the point:

If the situation was you wanted to buy a ball with strictly the money in your wallet, and the ball cost $50:
1. A necessary assumpton would be you would have $1 in your wallet to buy the ball. You MUST necessarily have 1 dollar to buy the ball, but the 1 dollar does not sufficiently satisfy the condition. If this is diagramed as a hollow conditional arrow, think of this situation as filling in part of the conditional arrow.
2. A sufficient assumption would be you have $100 in your wallet to buy the ball. You have a sufficient amoutn of money to buy the ball, but $100 is NOT necessary to bull the ball. You satisfy what is needed, but you do not necessarily have to hae $100 to buy the ball. If this sitatuation is diagramed as a hollow conditional arrow, think of this situation as filling in more that just the arrow and coloring outside the lines.
3. A necessary and sufficient assumption would be you have exactly $50 in your wallet to buy the ball. This number is not only required, but it is enough to fully satisfy the condition. This conditional arrow diagram fully colors in the hollow arrow.

In whole dollars:
1. Any amount from $1-49 is necessary
2. Any amount from $51+ is sufficient
3. $50 exactly is both necessary and sufficient

Idk if this is what you were even asking, but hope this helps

This is almost exactly the same example I use in my tutoring to illustrate these concepts! (Have I tutored you before?)

HAHA, no and i dont want to take credit for this. Again, almost exactly how manhattan puts it

In MLSAT LR, there's an exercise at the end of the Assumption chapter that I found VERY useful. It lists a bunch of statements under an argument and asks you to ascertain whether the statement is a necessary assumption, a sufficient assumption, a jointly necessary & sufficient assumption, or none of the above (so more or less irrelevant to the argument). It really helped me to grasp the necessary and sufficient distinction. More than that, it helped me to understand what doesn't constitute an assumption (as exemplified by the 'none of the above' option). While I didn't personally seek this out, I think it would've been great to have more of these types of exercises.

Nova wrote:Clicked cause I thought this was going to be about OCI interviews

In the lsat forum? Lol

Sorry to post again, but I just wanted to add this if your gettin confused on conditional logic in more abstract terms.

I always thought of the necessary as what is absolutely gonna happen in the event you provide me with the sufficient.

A --> B
A is sufficient
B is necessary

If you want to have A, and your gonna make the claim you have A, than you gotta bring B to the party too.
A is sufficient, $60
B, is necessary, $1

$60 --> $1

Likewise, if you negate the necessary ( You dont have $1, than you destroy the argument and show that the sufficient is also not met). Hope this helps.

As for your question, Manhattan LR is what I used and I really think it worked alot. Their focus on argument structure is reinforced throughout and they want you to understand structure, not just memorize how to solve question types. This helps you stay fluid and adapt to difficult questions.

Clearlynotstefan wrote:

Nova wrote:Clicked cause I thought this was going to be about OCI interviews

In the lsat forum? Lol

I mostly TLS through "view active topics"

I would like to contribute to the thread but im tooo rusty lol

Looks like a lot of solid explanations here

So, without the sufficient assumption, the whole argument cannot happen at all and it falls apart?

I think you may be talking about/thinking of a necessary assumption, which is necessary for the argument. Sufficient, to me, means its just one of possibly many ways that could satisfy the argument.

Anyway, I had trouble with SA questions bc 1. some are long 2. they are long with conditional logic. And the logic is used differently than on Must Be True questions. What helped is to summarize the argument by sifting through the unimportant info (background stuff) and taking out the most important info which I noticed sometimes could only be 1-2 lines. But then I also look at terms not mentioned in the premises but mentioned in the conclusion. If the term(s) are in the conclusion but not the premises they should also appear in the answer choice bc obviously that means theres a disconnect between premises and conclusion and we are trying to connect everything. Things mentioned in premises and conclusion, I dont pay particular attention too. This is by no means a full proof method but combined with some conditional diagramming and identifying the gap it should lead you towards the right answer!

flash21 wrote:So, without the sufficient assumption, the whole argument cannot happen at all and it falls apart?

It doesn't necessarily fall apart, but it's not complete. Sufficient assumptions can be negated and not destroy the argument.

To confuse you even more, sufficient assumptions can destroy an argument when they contain a necessary assumption. Sometimes a sufficient assumption IS a necessary assumption, meaning what is absolutely necessary for an argument to make logical sense is enough to assure the completeness of the argument.

I'm not creative enough to make my own example, so I'll illustrate this with #54 in the Cambridge packet. In this argument, the conclusion - a concrete statement - is made based off a premise that has not been proven by data. Everything else in the argument is pretty solid. In order for the conclusion to be true, it's necessary that the data proves the premise. However, if the data proves the premise, it also completes the argument. Nothing more would need to be said in order for it to be logically sound.

The analogy I can pull here between necessary and sufficient assumptions, pulling to another LR example that I can't remember, is between indictment and conviction. Not everyone who is indicted is convicted, but everyone who is convicted is indicted. The analogy doesn't fall exactly, but I think it gives some illustration.

Okay, so I think I am understanding what you guys are saying.

Could this work too though : If I draw the question out logically, with the conclusion being the necessary part of the logical chain, and the premises being the necessary part, would this also help lead to the answer of the question?