IF you are not T, then you are not V.
Diagram: NOT T> NOT V
The book also said V> T.
I don't know how can it get V>T. You are V doesn't mean you are T. am I wrong?
Thank you
Formal Logic question
 The Abyss
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Re: Formal Logic question
V > T is the contrapositive of /T > /V. Flip and negate. They are logically equivalent.
 lollsat
 Posts: 53
 Joined: Wed Mar 18, 2015 1:37 pm
Re: Formal Logic question
Hey buddy! It is V> T because that's the contrapositive to NOT T> NOT V. If you don't know what "contrapositive" is don't worry! I was there a few months ago when I was beginning my prep. There's an article on TLS that really helped me out that explains conditional logic fundamentals. Here it is: http://www.toplawschools.com/conditionalreasoning.html Someone will post here giving you a great explanation, still, I HIGHLY recommend going through that article as it thoroughly explains the basics. Good luck!

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Re: Formal Logic question
OK so we had T > V right?
That means if we don't have T, we most certainly don't have V  basically we need T to have V  so if we have V, then we must have T
It follows the method used to gain a contrapositive 
If you have T >  V
Switch places so it becomes V >T and then reverse signs (negative becomes positive, positive becomes negative and vice versa 
So it becomes V > T
__________________
Think of it in simpler terms:
If it's not round it's not a circle
So you'd have:
 (round) >  (circle)
Though irrelevant to LG (doesn't need to make sense if they give you a rule) but it makes sense since circles are round, so if it's not round how could it be a circle.
If you follow the contrapositive method, you'd get
circle > round
The rule gave us that if it's not round it can't be a circle. If it can't be a circle unless it's round, then we know that if it is a circle, then it must be round, otherwise it'd violate the original rule. Same idea with the original example of TV
That means if we don't have T, we most certainly don't have V  basically we need T to have V  so if we have V, then we must have T
It follows the method used to gain a contrapositive 
If you have T >  V
Switch places so it becomes V >T and then reverse signs (negative becomes positive, positive becomes negative and vice versa 
So it becomes V > T
__________________
Think of it in simpler terms:
If it's not round it's not a circle
So you'd have:
 (round) >  (circle)
Though irrelevant to LG (doesn't need to make sense if they give you a rule) but it makes sense since circles are round, so if it's not round how could it be a circle.
If you follow the contrapositive method, you'd get
circle > round
The rule gave us that if it's not round it can't be a circle. If it can't be a circle unless it's round, then we know that if it is a circle, then it must be round, otherwise it'd violate the original rule. Same idea with the original example of TV

 Posts: 12
 Joined: Sun Mar 22, 2015 6:11 pm
Re: Formal Logic question
thanks for your guys help
 RZ5646
 Posts: 2395
 Joined: Fri May 30, 2014 1:31 pm
Re: Formal Logic question
tequilawine wrote:IF you are not T, then you are not V.
Diagram: NOT T> NOT V
The book also said V> T.
I don't know how can it get V>T. You are V doesn't mean you are T. am I wrong?
Thank you
The other responses explained it but they didn't prove it, so I'll give it a shot with a reductio ad absurdum:
Say you're V. Then let's assume that you're ~T (not T). But then by your first conditional you must be ~V, and we just said that you're V. You have V and ~V at the same time, which is a contradiction. Thus the assumption that you are are ~T must be false, and its opposite must be true: you are T. Thus, if you are V, you are T, and V > T.
In general, any conditional p > q can be flipped into ~q > ~p. The flipped version is called the contrapositive, and it works both ways: ( p > q ) <> ( ~q > ~p ).
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