## Basic LG Bible ?

Prepare for the LSAT or discuss it with others in this forum.
whiteness

Posts: 37
Joined: Wed Apr 25, 2012 3:49 pm

### Basic LG Bible ?

Ok, I am trying to throw out everything I know and learn the LG Bible. This is a basic question, Im only in the 2nd chapter.

Will this mess me up and am I correct.

Ex. G does not speak fourth unless Q speaks second.

The book says G4--->Q2 and -(Q2)-----> -(G4)

I look at it like this is the same thing

Q2-->G4 and -(G4)---> -(Q2)

I think these are equivalent and its easier for me to think like that than the other way around depending on how the clue is written.

But before I get too much farther I would like someone to clarify this

shifty_eyed

Posts: 1925
Joined: Fri Oct 02, 2009 8:09 pm

### Re: Basic LG Bible ?

They are not equivalent. Q could be 2nd without G being 4th. This is called a mistaken reversal,I think in the LG bible. Review necessary and sufficient condition definitions.

whiteness

Posts: 37
Joined: Wed Apr 25, 2012 3:49 pm

### Re: Basic LG Bible ?

shifty_eyed wrote:They are not equivalent. Q could be 2nd without G being 4th. This is called a mistaken reversal,I think in the LG bible. Review necessary and sufficient condition definitions.

I see why it is wrong but for some reason my mind is thinking of it backwards. Is the first thing mentioned in the clue the first to be notated in the diagram.

Can anyone give an example where the 2nd term in the clue goes first in the diagram?

Br3v

Posts: 4272
Joined: Mon Jun 13, 2011 7:18 pm

### Re: Basic LG Bible ?

whiteness wrote:Ok, I am trying to throw out everything I know and learn the LG Bible. This is a basic question, Im only in the 2nd chapter.

Will this mess me up and am I correct.

Ex. G does not speak fourth unless Q speaks second.

The book says G4--->Q2 and -(Q2)-----> -(G4)

I look at it like this is the same thing

Q2-->G4 and -(G4)---> -(Q2)

I think these are equivalent and its easier for me to think like that than the other way around depending on how the clue is written.

But before I get too much farther I would like someone to clarify this

OP, here is what Powerscore gives as a "trick" for unless questions.

"when you see unless, it introduces the necessary condition, then negate the other condition to use as the sufficient condition"

So: A unless B
Not A > B or it's contra positive: Not B > A

If you say it to yourself in "real words" it makes sense

A unless B: "I have A unless I have B" so "if I don't have A, I know I have B"

Not G4 unless Q2
So we get: G4 > Q2 and contra: Not Q2 > NotG4

Say it out loud: G is not 4 unless Q is 2. So if G is 4 we know Q is 2.

Br3v

Posts: 4272
Joined: Mon Jun 13, 2011 7:18 pm

### Re: Basic LG Bible ?

Your fundamental problem seems to be that you do not fully understand necessary and sufficient conditions. Don't worry it takes a little to understand but keep at it as it is fundamental to the LSAT.

Though you can make up examples for conditional statements that are valid and not valid so be careful, sometimes it helps.

If I am eating dinner right now, then I am alive.

What is necessary and what is sufficient?
Well if you are eating, you know that you must be alive! So in this case being alive is necessary and eating dinner is the sufficient conditional.

You can be alive and not be eating dinner right? Yes
Can you be eating dinner but not be alive? No

So does being alive mean you are eating dinner? No not necessarily we cant be sure.

What you did was try to reverse G4 and Q2 and we can't do this even if we negate both it doesn't make it equal.

I suggest reading powerscores explanation of conditionals until you fully grasp it.

whiteness

Posts: 37
Joined: Wed Apr 25, 2012 3:49 pm

### Re: Basic LG Bible ?

I understand this concept now. Since I have nothing better to do on a Saturday night, I've been working through the LG bible, I just got to the first real game. I got all of them right! If I had done that game yesterday I would have missed half of them. I am impressed thus far.