7Sage Logic

NorthernAtticus

Hi guys,

I'm working through the core curriculum at the moment in preparation for the Sept. LSAT, and I'm getting a bit hung up at the logic section. A lot of my undergrad has been formal propositional and first order logic, and so many of my intuitions are being challenged by the unconventional way 7Sage teaches logic. For example, I would immediately translate the statement "No pilots are blind," as:

~∃x(P(x)^B(x)) - there does not exist an object that is a pilot and that is blind.

And of course the negation of that would just be ∃x(P(x)^B(x)) - there exists some object that is a pilot and that is blind.

Do you think it's worth 'reprogramming' myself to do things 7Sage's way, or just stick with the way I've been doing it for years? I guess I'm just a bit concerned that there is something specific to the LSAT where conventional logical notation would fail, and it would be worth knowing 7Sage's method.

Daniel.Sieradzki

Hi @"alaric.taves",

Great question. Like you, I had exposure (though not as much as you) to logic before 7Sage. In college, I took two classes devoted to logic and a bunch of philosophy and discrete math classes that used logic.

7Sage does a great job of teaching the logic (lawgic) used on the LSAT. However, as you know, there is a lot more to logic than what the LSAT tests. Thus, we know more than we need to know and learning logic from 7Sage can feel a little weird. It seems to be geared to people who are relatively new to formal logic systems.

That being said, I still think there are valuable logic lessons to learn from 7Sage. The LSAT loves to use and test you on conditional statements. Thus, the statement you mentioned: "No pilots are blind" would best be translated to the conditional statement: P --> ~B or if you prefer B --> ~P. Your use of predicate logic and existential quantifiers is great but not very helpful on the LSAT. I think it might be worth learning the translations for the four groups of statements that 7Sage covers in its logic lessons. The rest of the material you likely will not need given your background. It is really nice being able to translate an LSAT statement into a conditional statement in a matter of two seconds because of 7Sage's group breakdown.

I hope this helps. Good luck! Also, let me know if you have any other questions.

akistotle

I cannot answer your question, but I think it depends on your diagnostic PT score. If you are already scoring high 160s - 170s, I don't think you should change your method.

I hope someone with your background can answer your question!!

Edit: I commented before refreshing this page so I missed @"Daniel.Sieradzki" 's comment! Sorry!

NorthernAtticus

Thanks for the responses! @Daniel.Sieradzki Thank you, that's exactly what I was looking for. I was making a point to try to stick to the basic conditional statements without quantifying over anything or using other connectives, but then the "some" notation was introduced which seems to be used sort of like a pseudo-existential quantifier. I'll definitely make sure I have the 4 groups down. J.Y. tends to go into such exquisite detail at times, which I think might be causing me to overthink this!

jknauf

@"alaric.taves" said:
Thanks for the responses! @Daniel.Sieradzki Thank you, that's exactly what I was looking for. I was making a point to try to stick to the basic conditional statements without quantifying over anything or using other connectives, but then the "some" notation was introduced which seems to be used sort of like a pseudo-existential quantifier. I'll definitely make sure I have the 4 groups down. J.Y. tends to go into such exquisite detail at times, which I think might be causing me to overthink this!

Oh gosh, I was the opposite of you guys. I had very little training in Formal Logic. After learning some basic logic by studying the LSAT, I figured it would be fruitful to try and develop a deeper understanding. So I did what any wanna be academic does! Went to the library and checked out a formal logic book. Man, was I in for a rude awakening. It was like reading Chinese.

The LSAT authors will reward you for your deeper understanding of logic. So you are off to a great start and have a leg up on many of us.

Good luck in your studies!