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Q. When to and not to use formal logic and/or contrapositives
How do you diagram this
J is selected unless W is selected
J is selected if and only if W is selected
If W is not selected then J is not selected
Either J or W must be selected
Help anyone
Comments
W-> JW->JW-> J andJ-> WYou can use formal logic whenever you have words that trigger formal logic - if, unless, without, etc. I suggest signing up for a 7sage course or purchasing the LSAT Trainer - it'll help you sort these out.
ETA: (I'm a little rusty so a good exercise would be to check my work)
*"unless" means "negate the sufficient". Pick either variable, make it the sufficient indicator and then negate it.
*"If and only if" means the two variables have a bi-conditional relationship. Which means the arrow goes both ways.
*"if" is a sufficient condition indicator. Keep the properties of "not" for both the variables.
*"Or" means one of the variables has to be selected. That means we know that if one of them is not selected the other one absolutely now has to be selected.
*Once you have at least a conditional statement written down, you can just do the contrapositive of that statement. Don't worry about if you are required to do the contrapositive right of the back.
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*I hope that helps.
You should be using formal logic whenever you can. When I first began studying, I would have to bracket the premises and conclusion so I could parse through the argument. Now it's completely intuitive, my mind does this automatically. Once you improve your understanding of logic, your mind will begin to diagram intuitively.
It will all make sense with time and dedication!
Thanks everyone. Can any of this be used in connection to relative ordering?
When I work through the books I am able to follow, sometimes, but when I go to the practice test, there is always something different or improvised that causes me to freak out. Are there any precedence rules or words of encouragement when tackling challenging logic games.
I'm not entirely sure what you are asking.
Are you referring to conditionals which aren't just simple IF a then b statements?
To pull an example from an LR question: 'It is wrong to waste our natural resources, and it is an incredible waste of resources to burn huge amounts of trash in incinerators'
This translates into: BHATI ---> WR ---> W
or the contrapositive
/W --> /WR --> /BHATI
and from here we can make a couple inferences
BHATI ---> W and /W --> /BHATI
Well even though my example is from an LR question, it still uses the same fundamental knowledge or skills of formal logic which you would use on a logic game.
In order to really get better at this skill, it takes time. You have to be able to parse through complex language in the shortest amount of time possible. A difficult task no doubt, but needed for mastery of LSAT skills.
My advice would be to really 'meditate' on the idea of what sufficient and necessary conditions are. Really hone in on what makes them sufficient or necessary and as you begin to develop this skill speed will come.
Do your best to understand valid argument forms and invalid argument forms. There is plenty of beneficial lessons on the 7sage core curriculum so I would recommend purchasing a 7sage package. If you don't like it, I believe there is a 7 or 14 day money back guarantee policy. All you would have to do is contact @"Dillon A. Wright" . If you are still against this, I would recommend a book on formal logic.
There's no real shortcut, just time, patience, and effort.
Best wishes
Yup, 14 days!
This course sounds really exciting and helpful. Is there a time period for completion or can one study at their own pace?
It has a Schedule you can adhere to that is recommend. But you can also go at your own pace!