Advice on improving and understanding Necessary/ Sufficient Conditions in LG Forum

[AlexandraHope]

So, I noticed a pattern in my LGs and the majority of the questions that I miss have something to do with that and they also seem to take up the most time. What would be the best way to approach the separating of necessary and sufficient conditions? I know in my LG Bible, there was a list of key words. I was thinking about making flash cards; but I am also weary about how helpful that would be.

[justkeepswimming794]

So, I noticed a pattern in my LGs and the majority of the questions that I miss have something to do with that and they also seem to take up the most time. What would be the best way to approach the separating of necessary and sufficient conditions? I know in my LG Bible, there was a list of key words. I was thinking about making flash cards; but I am also weary about how helpful that would be.

if you're still in school, take a formal logic class. if not, consider investing in an online LSAT course specific in LG. (I did that.) If all else fails:http://plato.stanford.edu/entries/necessary-sufficient/ read as much as you can. I have a masters in Philosophy, message me if you want to chat further.

[Manhattan Prep Matt]

There are very few things on the LSAT that I think are ideally learned through memorization. The conditional logic keywords are on that list.

The reason is twofold:
1) It's formal logic, so a formal approach is warranted.
2) Most of the LSAT is testing a skill, so memorization can hurt your ability to perform (rigidly memorizing things makes it harder to apply flexibly). However, formal logic isn't testing flexible thinking.

On LG, if you have the keywords memorized and apply that to the rules, I actually think you're in better shape than if you have an intuitive sense of the language. The writers of the test are really good at phrasing individual rules, or clusters of rules, in a way that subverts your natural understanding of language (think of a series of rules that all have "if" halfway through, and then a final rule with an "only if" - tell me you've never misdiagrammed that rule!). If, however, your approach to formal logic is formulaic and involves straight recall of the keywords, you're more likely to slow down, highlight the keyword, and apply the rules that you've memorized.

That said, it's important to work with the keywords, not just memorize the list. So definitely work through many, many examples. You can create flashcards including rules that are pulled from actual Games for that purpose.

[eli2015]

So, I noticed a pattern in my LGs and the majority of the questions that I miss have something to do with that and they also seem to take up the most time. What would be the best way to approach the separating of necessary and sufficient conditions? I know in my LG Bible, there was a list of key words. I was thinking about making flash cards; but I am also weary about how helpful that would be.

Take a 7sage course, I promise you will not regret it.

[BlueprintJason]

I would memorize all of the sufficient and necessary indicator words in the lists that you have. I would streamline the process by learning it one way really well and applying the rules like a math formula.

But, I would take it a step further than the other posters have mentioned--particularly for phrases that are giving you trouble. One think that really helps internalize this (rather than just learn some abstract rules) is making up your own examples and to drill yourself on them.

One that messes with students is the phrase "the only." Typically the thing that comes right after "only" or "only if" is the necessary condition, but the phrase "the only" actually precedes the sufficient condition.

The "rule" way is just to remember that "the only" is THE ONLY EXCEPTION to the only family.

But, if you just make a few examples, you'll learn it anyhow.

What I do for this is draw a line down the middle of a piece of paper. Then, on the left, I write out a made up example that highlights the thing I'm working on. On the right, I write the correct way to write the conditional statement with diagramming (plus contrapositive).

So for this one I could write:

The only cars allowed (CA) in the show are ones with spinner rims (SR). (Seems reasonable). ||||| other side ||||| CA-->SR / not SR--> not CA

Heavy binge-drinking (HBD) is the only way to succeed in life (SL). |||| other side ||||| SL --> HBD / not HBD --> not SL

The utility of this approach is that you are initially encoding the material into your brain in a way that makes you work with the material and learn by doing. Recall is usually better when you learn this way. The other reason is that you now have a built in set of practice drilling for future use. I would use these types of drills with my students as a warm up before having them do logic games with conditional grouping heavy rules (or especially tricky rules).

HTH

Jason

[giantswan]

I used the LG Bible and I think they key words are the only thing that I can remember that felt completely useless to me. You may find them helpful depending on your learning style, but I thought of them as a last resort measure (if even that). Personally I thought that if I needed key words to point out sufficient and necessary conditions (or anything else) that probably meant that I didn't have a great grasp on the underlying logic or maybe I was just bad at reading/diagramming the game. Either way, learning key words felt a bit like treating the symptom.

I think what you should really be spending time on is looking at questions (in LG or LR) that deal with sufficient/necessary conditions and making sure you fully understand the concept. If you do, maybe what you should be looking at is if you are reading the game/diagramming in a way that is messing you up.

[BlueprintJason]

I used the LG Bible and I think they key words are the only thing that I can remember that felt completely useless to me. You may find them helpful depending on your learning style, but I thought of them as a last resort measure (if even that). Personally I thought that if I needed key words to point out sufficient and necessary conditions (or anything else) that probably meant that I didn't have a great grasp on the underlying logic or maybe I was just bad at reading/diagramming the game. Either way, learning key words felt a bit like treating the symptom.

I think what you should really be spending time on is looking at questions (in LG or LR) that deal with sufficient/necessary conditions and making sure you fully understand the concept. If you do, maybe what you should be looking at is if you are reading the game/diagramming in a way that is messing you up.

I do disagree that learning the rules is useless (most students really benefit from learning rules for conditional statements in my experience teaching, and most students really struggle with diagramming that don't) I definitely agree that it's best to really internalize and understand things so that you can sort of "forget" the rules and just understand how to diagram naturally.

Making your own examples really helps with this. If you know how to diagram every conditional combo possible, and you know it intuitively, then you'll always do it right when it counts.

But I understand what you mean. Some students don't respond as well to the rule memorization system and really struggle with it. Unfortunately (not saying this is the case for you) the students that resist mastering the rules and don't adequately practice tend to be the ones who continue to make diagramming mistakes until the end. Definitely agree that applying the skills in actual questions should be the majority of time spent, but only once the concepts are first mastered. Otherwise, students tend to practice bad habits.

[giantswan]

I used the LG Bible and I think they key words are the only thing that I can remember that felt completely useless to me. You may find them helpful depending on your learning style, but I thought of them as a last resort measure (if even that). Personally I thought that if I needed key words to point out sufficient and necessary conditions (or anything else) that probably meant that I didn't have a great grasp on the underlying logic or maybe I was just bad at reading/diagramming the game. Either way, learning key words felt a bit like treating the symptom.

I think what you should really be spending time on is looking at questions (in LG or LR) that deal with sufficient/necessary conditions and making sure you fully understand the concept. If you do, maybe what you should be looking at is if you are reading the game/diagramming in a way that is messing you up.

I do disagree that learning the rules is useless (most students really benefit from learning rules for conditional statements in my experience teaching, and most students really struggle with diagramming that don't) I definitely agree that it's best to really internalize and understand things so that you can sort of "forget" the rules and just understand how to diagram naturally.

Making your own examples really helps with this. If you know how to diagram every conditional combo possible, and you know it intuitively, then you'll always do it right when it counts.

But I understand what you mean. Some students don't respond as well to the rule memorization system and really struggle with it. Unfortunately (not saying this is the case for you) the students that resist mastering the rules and don't adequately practice tend to be the ones who continue to make diagramming mistakes until the end. Definitely agree that applying the skills in actual questions should be the majority of time spent, but only once the concepts are first mastered. Otherwise, students tend to practice bad habits.

I did not say learning the rules is useless - just the key words. In fact what you just did, using "key words" and "rules" interchangeably, is another reason I dislike key words so much. If "key words" are all you have for rules, I think you've got a pretty poor strategy. Unfortunately I have heard from more than a couple people who seem to think that memorizing the key words is the best tool they have. I think there are a lot of "rules" you can learn that make sense and are more useful. Maybe to Blueprint memorizing a list of key words is the same thing as learning rules - but to me that seems to be giving a lot of credit to key words.

I do agree that applying the skills is more useful after you have mastered the concept - I just disagree that key words are the best way to master any concept.

Just my opinion - as I said before some people might find them useful.

[BlueprintJason]

I used the LG Bible and I think they key words are the only thing that I can remember that felt completely useless to me. You may find them helpful depending on your learning style, but I thought of them as a last resort measure (if even that). Personally I thought that if I needed key words to point out sufficient and necessary conditions (or anything else) that probably meant that I didn't have a great grasp on the underlying logic or maybe I was just bad at reading/diagramming the game. Either way, learning key words felt a bit like treating the symptom.

I think what you should really be spending time on is looking at questions (in LG or LR) that deal with sufficient/necessary conditions and making sure you fully understand the concept. If you do, maybe what you should be looking at is if you are reading the game/diagramming in a way that is messing you up.

I do disagree that learning the rules is useless (most students really benefit from learning rules for conditional statements in my experience teaching, and most students really struggle with diagramming that don't) I definitely agree that it's best to really internalize and understand things so that you can sort of "forget" the rules and just understand how to diagram naturally.

Making your own examples really helps with this. If you know how to diagram every conditional combo possible, and you know it intuitively, then you'll always do it right when it counts.

But I understand what you mean. Some students don't respond as well to the rule memorization system and really struggle with it. Unfortunately (not saying this is the case for you) the students that resist mastering the rules and don't adequately practice tend to be the ones who continue to make diagramming mistakes until the end. Definitely agree that applying the skills in actual questions should be the majority of time spent, but only once the concepts are first mastered. Otherwise, students tend to practice bad habits.

I did not say learning the rules is useless - just the key words. In fact what you just did, using "key words" and "rules" interchangeably, is another reason I dislike key words so much. If "key words" are all you have for rules, I think you've got a pretty poor strategy. Unfortunately I have heard from more than a couple people who seem to think that memorizing the key words is the best tool they have. I think there are a lot of "rules" you can learn that make sense and are more useful. Maybe to Blueprint memorizing a list of key words is the same thing as learning rules - but to me that seems to be giving a lot of credit to key words.

I do agree that applying the skills is more useful after you have mastered the concept - I just disagree that key words are the best way to master any concept.

Just my opinion - as I said before some people might find them useful.

I understand that you meant that you personally found memorizing key words useless, I just don't think the majority of students are able to intuit this kind of thing as easily as you might have in your prep (maybe you just have a learning style that's different than most). I've taught hundreds of students by now, and I can assure you that this has been the case in my experience. So I don't agree that they are useless [read: for other people that might be reading this, I'm not trying to convince you, you already did well and got a great outcome]. I'm more concerned here with people who might be reading this thinking that your results are typical--they're not. Most people don't read a convoluted conditional statement on the LSAT and instantly have an intuitive sense of the way you would diagram or understand what exactly follows from it until mastering a lot of basic skills and doing a lot of drill work, which our curriculum provides.

As to the distinction between rules and keywords, I was speaking about learning a key rule in the context of learning the rule associated with that key word--I thought that was pretty clear from the context of our discussion. As in, the phrase "only if" always precedes a necessary condition. That's a rule that requires learning a "key word" for it to be applied. They aren't all I have to teach students (or all Blueprint has for that matter), they are just one example of a type of rule that we teach related to key word usage. I wasn't speaking in absolutes here. Of course, our students learn all the different mutations of conditional logic necessary for the LSAT and learn the key deductions that follow from combining conditionals, etc.

Again, I didn't say that learning key words was the best way to master "any" concept. That's not fairly characterizing what I was saying at all. I'm just saying that for that particular concept (which thing signifies a suff/nec condition for the purposes of creating a visual diagram to represent the logic), most students do better when they learn the rules associated with the key words and learn how to apply them by making examples.

[Pierce]

From my experience, reading about necessary and sufficient conditions from a number of different sources (many can be found online) can help to build an understanding. With this improved understand, you should also be able to more easily recognize terms that denote them. You can then use this recognition and understanding to drill questions until the point that you can quickly and easily answer them under timed pressure.