Improving on PowerScore's "Double Not Arrow"--See Quinn's Improved Improvement in the Comments

attorneysomerville

The "/A->B" rule is so important for grouping games that PowerScore uses a special symbol ("A<-|->B", or "the double-not arrow") to note it. As a person who understands how important this is for grouping games, I think the "double-not arrow" is brilliant. As a person who has tried to explain it to others, it is both frustrating and confusing. The "double not arrow" is ONLY used when the sufficient term is negative and the necessary term is positive--or is it the opposite? It makes a huge difference, but I find it almost impossible to keep it straight in my head, much less explain it to someone else. For that reason, I think JY is wise to avoid using it here at 7Sage.

But what if it were not confusing? I have come up with TWO arrows that practically write themselves and make grouping games much easier. All you have to do is look at the way we write out "/A->B" and "A->/B."

Note how the slash comes first in the "/A->B" situation, but comes second in the "A->/B" case. Let's turn those slashes into pictures. If we put the forward slash first, we can make a "/\" picture. If we put it second, we get a "\/" picture.

/A->B turns into A<-/\->B
A->/B turns into A<-\/->B

Pictures are helpful if they mean something, so let's call the "/\" picture an "erupting volcano." The "erupting volcano arrow" means that something is erupting, so that something must be in your slot. The "\/" looks like a "leaky funnel," which means something is leaking, which means something must be OUT.

If you can remember that "slash comes first" means "/\," and "/\" means "erupting volcano," and "erupting volcano" means something must be in, you can turn a "/A->B" rule into a full slot within seconds. And if you can remember what a "leaky funnel" does, you'll fill an out slot just as fast.

And there's no reason to ever get them mixed up!

quinnxzhang

I think this is all too convoluted. Much simpler to just understand that, classically, "A→B" is equivalent to "~A or B".

So for "~A→B", this is equivalent to "~~A or B", which is in turn classically equivalent to "A or B". This means at least one of A and B must be in.

And for "A→~B", this is equivalent to "~A or ~B". This means at least one of A and B must be out.

This is simpler than having to remember another mnemonic and involves a deeper understanding of how the LSAT treats conditionals.

attorneysomerville

Quinn, I agree with your logic but not your advice. I can figure out "/A->B" on the fly by saying, "So... if A is IN, B can go anywhere, so they can both be in." But... it takes a moment to work that out, and it would take ME a moment to work out the same result using your method. PowerScore uses the "double-not arrow" to save that moment, and I think there is some merit to that. It's just that I haven't figured out a way to reliably USE the double-not arrow for its intended purpose because I'm always second-guessing myself (is that both in or both out? Did I write that down properly?).

Bottom line: there's a trade-off between fast and simple. People who use flashcards are trying to get their speed up by exchanging a thought process for instant recognition. I PREFER working out the logic in my head, but I only have 35 minutes on a logic game section, and a fast, reliable mnemonic may have its advantages.

Having said all that... I love your explanation of the "NOT A or B" mode, and I'm going to try it out with some guinea pigs. If I can explain that effectively, I'll gladly use it instead of a new mnemonic. If I can't, though, I think I'll stick with my "erupting volcano" and "leaky faucet" pictures.

attorneysomerville

So... I'm still thinking through what you said, Quinn. I hadn't thought of writing down the original statement in the "A or B" form. THAT would be fast, easy, and powerful. Likewise, I should read a "A->/B" rule and write down "/A or /B," which is probably better expressed as "NOT (A AND " (which I would write as an AB block with a slash through it.

So... thinking this out... I read "/A->B," and I write down "A/B." I read "A->/B," and I write down "NOT [AB]." Right?

attorneysomerville

Just went over this and got to try out the "A/B" and "/[AB]" explanations. It went great. SO much for making up two new symbols to replace the "double not arrow." Let's go with Quinn's approach!

Admin edit: You know why I edited this. Last warning.

Alex

I prefer the 7Sage/The LSAT Trainer's logical diagramming methods better. My reasoning is that The Bible's always seemed gimmicky to me and while you may have found a way to simplify their already confusing way, I think anyone would be better off just starting and using 7Sage, especially for conditional logic.

attorneysomerville

Actually, I don't know why you edited it, but I see I better err on the super safe side. I value the input I get here tremendously, and I am NOT trying to exploit this side to boost my own business. This community is one of the finest places on the Internet for testing out ideas and seeing what is the BEST way to learn the LSAT, and I am eager to promote 7Sage.

S.P. 170

I worked through evey page og powerscore LG and my score did not improve. I've been doing 7sage LG for a couple weeks. Score is improving. I trust in JY's method because it has given me results by actually helping me to UNDERSTAND what is going on. The double not arrow didn't help me understand anything, actually.

jennilynn89

I'm going to have to agree with @"S.P. 170" and @"Alex Divine" the double arrow is really confusing, and the information is pretty convoluted.
The powerscore bibles didn't do anything, but confused me even further... I really wished I had started out with the 7Sage curriculum from the beginning.
Clear and Simple learning = success!