## "Unless" statement Brainfart!

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brooklynballers

Posts: 16
Joined: Sat Feb 20, 2010 4:25 pm

### "Unless" statement Brainfart!

N cannot be selected unless L is selected.

Isn't this supposed to diagrammed as L --> N?

doyleoil

Posts: 628
Joined: Sat Oct 11, 2008 2:59 pm

### Re: "Unless" statement Brainfart!

brooklynballers wrote:N cannot be selected unless L is selected.

Isn't this supposed to diagrammed as L --> N?

just the opposite (meaning, N ---> L)

artichoke

Posts: 760
Joined: Mon Jun 21, 2010 11:20 pm

### Re: "Unless" statement Brainfart!

No. N--->L

if N is selected, you know L has been as well because N can only be selected if L is.

brooklynballers

Posts: 16
Joined: Sat Feb 20, 2010 4:25 pm

### Re: "Unless" statement Brainfart!

doyleoil wrote:
brooklynballers wrote:N cannot be selected unless L is selected.

Isn't this supposed to diagrammed as L --> N?

just the opposite (meaning, N ---> L)

Could you explain the process of getting to your diagram?

agentcom

Posts: 76
Joined: Thu Oct 09, 2008 7:59 pm

### Re: "Unless" statement Brainfart!

Umm it's been a while, but wouldn't it be:

~L --> ~N

doyleoil

Posts: 628
Joined: Sat Oct 11, 2008 2:59 pm

### Re: "Unless" statement Brainfart!

agentcom wrote:Umm it's been a while, but wouldn't if be:

~L --> ~N

This isn't a bad place to start, because I think the best, most common sense, way to get to the diagram is to say to yourself "what happens if L isn't there?" If L isn't there, then N isn't there. And the contrapositive of that is "N ----> L"

agentcom

Posts: 76
Joined: Thu Oct 09, 2008 7:59 pm

### Re: "Unless" statement Brainfart!

Edit: What doyle said

brooklynballers

Posts: 16
Joined: Sat Feb 20, 2010 4:25 pm

### Re: "Unless" statement Brainfart!

So you could select L, but not necessarily select N right?

Jeffort

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

### Re: "Unless" statement Brainfart!

brooklynballers wrote:So you could select L, but not necessarily select N right?

Yes

blackwater88

Posts: 197
Joined: Tue Feb 09, 2010 1:40 pm

### Re: "Unless" statement Brainfart!

unless: if not
DONE

brooklynballers

Posts: 16
Joined: Sat Feb 20, 2010 4:25 pm

### Re: "Unless" statement Brainfart!

blackwater88 wrote:unless: if not
DONE

So the best way to think of it would be:

N can not be selected (if not) L is selected
OR
N can not be selected if L is not selected.

Which gives us:
If L is not selected, then N is not selected.

Contrapositive:
N --> L

Audio Technica Guy

Posts: 317
Joined: Tue Jun 29, 2010 5:21 pm

### Re: "Unless" statement Brainfart!

"if not" works. Some people have just as hard of a time with if not as they do with unless though, and if that is the case, just think "whatever comes immediately after unless goes on the right side, the other thing goes on the left and negated."

Jeffort

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

### Re: "Unless" statement Brainfart!

Audio Technica Guy wrote:"if not" works. Some people have just as hard of a time with if not as they do with unless though, and if that is the case, just think "whatever comes immediately after unless goes on the right side, the other thing goes on the left and negated."

I like the 2nd one bolded above more. It is less confusing and faster since it is pretty brainless and mechanical with less translation steps.

blackwater88

Posts: 197
Joined: Tue Feb 09, 2010 1:40 pm

### Re: "Unless" statement Brainfart!

Jeffort wrote:
Audio Technica Guy wrote:"if not" works. Some people have just as hard of a time with if not as they do with unless though, and if that is the case, just think "whatever comes immediately after unless goes on the right side, the other thing goes on the left and negated."

I like the 2nd one bolded above more. It is less confusing and faster since it is pretty brainless and mechanical with less translation steps.

To me "if not" works much faster, to be honest I first learned the bolded part, when I thought about "if not" it made me doubt since I didn't grasp the concept of "unless" that well. However, if you just take it as it is and substitute "unless" for "if not" every time it appears, there really is no transitional thinking. Just like you should memorize that all As are Bs = A ==> B

Unshake

Posts: 90
Joined: Wed Jan 20, 2010 3:00 pm

### Re: "Unless" statement Brainfart!

If you're using the logical reasoning bible, check out page 126 and maybe review all of chapter six. Basically what is explained here is correct; if you see the word "unless" (and some other words like until or except) whatever is modified by this becomes the necessary condition.