## Diagramming conditional reasoning involving Unless

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stray

Posts: 213
Joined: Thu Dec 23, 2010 12:18 pm

### Diagramming conditional reasoning involving Unless

I thought when using unless (as well as until, without, and except) you had to use the event/condition that unless modifies as the necessary condition, and negate the other event/condition and use that as the sufficient condition.

So why is this:
Unless they find an eyewitness and put the defendant on the stand, they will lose the case.

Diagrammed as this: LC --> FE and DS

LC - lose case, FE - find eyewitness, DS - defendant on stand.

Shouldnt we negate lose case and make it NOT lose case?

stray

Posts: 213
Joined: Thu Dec 23, 2010 12:18 pm

### Re: Diagramming conditional reasoning involving Unless

Anyone know where I'm getting it wrong? This is killing me.

lovejopd

Posts: 544
Joined: Tue Dec 01, 2009 1:00 pm

### Re: Diagramming conditional reasoning involving Unless

Treat Unless as "Not If"

Not(FE AND DS)-->LC

=Contrapositive

Not LC --> FE OR DS

HTH

stray

Posts: 213
Joined: Thu Dec 23, 2010 12:18 pm

### Re: Diagramming conditional reasoning involving Unless

lovejopd wrote:Treat Unless as "Not If"

Not(FE AND DS)-->LC

=Contrapositive

Not LC --> FE OR DS

HTH

I dont think I understand. The only issue I am having is trying to understand why its not negated as PowerScore taught me. I have been using that rule for a bit now and then this example just goes against it and its really just bugging me out.

Jeffort

Posts: 1888
Joined: Wed Jun 18, 2008 4:43 pm

### Re: Diagramming conditional reasoning involving Unless

ColumbiaBigLaw wrote:I thought when using unless (as well as until, without, and except) you had to use the event/condition that unless modifies as the necessary condition, and negate the other event/condition and use that as the sufficient condition.

So why is this:
Unless they find an eyewitness and put the defendant on the stand, they will lose the case.

Diagrammed as this: LC --> FE and DS

LC - lose case, FE - find eyewitness, DS - defendant on stand.

Shouldnt we negate lose case and make it NOT lose case?

Why do you think the diagram you posted is correct? It is incorrect, LC should be negated as you suggest at the end of your post.

Jeffort

Posts: 1888
Joined: Wed Jun 18, 2008 4:43 pm

### Re: Diagramming conditional reasoning involving Unless

ColumbiaBigLaw wrote:
lovejopd wrote:Treat Unless as "Not If"

Not(FE AND DS)-->LC

=Contrapositive

Not LC --> FE OR DS

HTH

I dont think I understand. The only issue I am having is trying to understand why its not negated as PowerScore taught me. I have been using that rule for a bit now and then this example just goes against it and its really just bugging me out.

As in my previous post, why do you think the example you posted is correct? It is not.

stray

Posts: 213
Joined: Thu Dec 23, 2010 12:18 pm

### Re: Diagramming conditional reasoning involving Unless

Jeffort wrote:
ColumbiaBigLaw wrote:I thought when using unless (as well as until, without, and except) you had to use the event/condition that unless modifies as the necessary condition, and negate the other event/condition and use that as the sufficient condition.

So why is this:
Unless they find an eyewitness and put the defendant on the stand, they will lose the case.

Diagrammed as this: LC --> FE and DS

LC - lose case, FE - find eyewitness, DS - defendant on stand.

Shouldnt we negate lose case and make it NOT lose case?

Why do you think the diagram you posted is correct? It is incorrect, LC should be negated as you suggest at the end of your post.

PowerScore told me its correct. And whats really frustrating is that not 10 pages ago it taught you the Unless/Except/Without/Until Rules where you negate the sufficient condition.

Jeffort

Posts: 1888
Joined: Wed Jun 18, 2008 4:43 pm

### Re: Diagramming conditional reasoning involving Unless

ColumbiaBigLaw wrote:
Jeffort wrote:
ColumbiaBigLaw wrote:I thought when using unless (as well as until, without, and except) you had to use the event/condition that unless modifies as the necessary condition, and negate the other event/condition and use that as the sufficient condition.

So why is this:
Unless they find an eyewitness and put the defendant on the stand, they will lose the case.

Diagrammed as this: LC --> FE and DS

LC - lose case, FE - find eyewitness, DS - defendant on stand.

Shouldnt we negate lose case and make it NOT lose case?

Why do you think the diagram you posted is correct? It is incorrect, LC should be negated as you suggest at the end of your post.

PowerScore told me its correct. And whats really frustrating is that not 10 pages ago it taught you the Unless/Except/Without/Until Rules where you negate the sufficient condition.

That's what happens when you use an old pirated pdf version of the LRB you got for free(stole) via a torrent or other download source and don't even check for errata reports about old versions. The example you gave is an error that was only in the original printings of the LRB from many many years ago when the book first came out and in a pdf version of the original version given to PS students at the time that got leaked out into file sharing land.

You should buy a current copy of the book, there have been some changes since the first version. Here is the full list of errors from all older versions: (but you should really do the honorable thing and buy a legit copy)
http://www.powerscore.com/lrbible/conte ... ctions.cfm

stray

Posts: 213
Joined: Thu Dec 23, 2010 12:18 pm

### Re: Diagramming conditional reasoning involving Unless

Jeffort wrote:
ColumbiaBigLaw wrote:
Jeffort wrote:
ColumbiaBigLaw wrote:I thought when using unless (as well as until, without, and except) you had to use the event/condition that unless modifies as the necessary condition, and negate the other event/condition and use that as the sufficient condition.

So why is this:
Unless they find an eyewitness and put the defendant on the stand, they will lose the case.

Diagrammed as this: LC --> FE and DS

LC - lose case, FE - find eyewitness, DS - defendant on stand.

Shouldnt we negate lose case and make it NOT lose case?

Why do you think the diagram you posted is correct? It is incorrect, LC should be negated as you suggest at the end of your post.

PowerScore told me its correct. And whats really frustrating is that not 10 pages ago it taught you the Unless/Except/Without/Until Rules where you negate the sufficient condition.

That's what happens when you use an old pirated pdf version of the LRB you got for free(stole) via a torrent or other download source and don't even check for errata reports in new versions. The example you gave is an error that was only in the original printings of the LRB from many many years ago when the book first came out and in a pdf version of the original version given to PS students at the time that got leaked out into file sharing land.

You should buy a current copy of the book, there have been some changes since the first version. Here is the full list of errors from all older versions: (but you should really do the honorable thing and buy a legit copy)
http://www.powerscore.com/lrbible/conte ... ctions.cfm

Yikes! I didnt want to buy a current version because I dropped mad dough on the Manhattan books, but I was having trouble with it and I heard power score gives you a better foundation. So I thought I'd just skim this version as a supplement to Manhattan. I was actually finding it very helpful before this. Thanks for the help though.

Damn, I dont know if I should just try and sell the Manhattan books and buy the updated Powerscore set because I am actually liking it better.

Jeffort

Posts: 1888
Joined: Wed Jun 18, 2008 4:43 pm

### Re: Diagramming conditional reasoning involving Unless

If you're going to use it, you should do the ethical thing and buy it, wanting to be a lawyer and all. One day you'll appreciate getting paid for stuff you put a lot of work into writing for others.

stray

Posts: 213
Joined: Thu Dec 23, 2010 12:18 pm

### Re: Diagramming conditional reasoning involving Unless

Jeffort wrote:If you're going to use it, you should do the ethical thing and buy it, wanting to be a lawyer and all. One day you'll appreciate getting paid for stuff you put a lot of work into writing for others.

Nah, I get that. Money's just kind of tight, so I wanted to get either the Manhattan set or Powerscore set, and unfortunately feel like I made a mistake by just going straight to Manhattan. Soo when I realized I wasnt really getting the concepts, it was too late, one thing led to another, and nooooowww I'm looking like an idiot. I should have opted for the Powerscore before anything else. I'm going to look for a cheap, used version.

rambleon65

Posts: 185
Joined: Mon May 13, 2013 2:05 pm

### Re: Diagramming conditional reasoning involving Unless

ColumbiaBigLaw wrote:
Jeffort wrote:If you're going to use it, you should do the ethical thing and buy it, wanting to be a lawyer and all. One day you'll appreciate getting paid for stuff you put a lot of work into writing for others.

Nah, I get that. Money's just kind of tight, so I wanted to get either the Manhattan set or Powerscore set, and unfortunately feel like I made a mistake by just going straight to Manhattan. Soo when I realized I wasnt really getting the concepts, it was too late, one thing led to another, and nooooowww I'm looking like an idiot. I should have opted for the Powerscore before anything else. I'm going to look for a cheap, used version.

"Unless they find an eyewitness and put the defendant on the stand, they will lose the case."

Not lose case -> Find witness AND Defendant on stand
If not find witness OR defendant on stand -> lose case

(the "AND" in the necessary condition turns to "OR" when you negate it for a contrapositive)

Also, spending an extra few bucks now to get a solid LSAT score could mean literally thousands of dollars after applications. Just remember that and good luck!

bp shinners

Posts: 3086
Joined: Wed Mar 16, 2011 7:05 pm

### Re: Diagramming conditional reasoning involving Unless

lovejopd wrote:Treat Unless as "Not If"

Not(FE AND DS)-->LC

=Contrapositive

Not LC --> FE OR DS

HTH

Not correct. When you negate an AND, it becomes an OR. So that original statement/the contrapositive is wrong (the original is technically correct, but from your contrapositive, I think you didn't realize that the AND in your original statement is really an OR since the NOT applies to it) (~=NOT):
~FE or ~DS -> LC
~LC -> FE AND DS

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