Basic conditionals

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tke1600
Posts: 9
Joined: Wed Jul 03, 2013 9:30 pm

Basic conditionals

Postby tke1600 » Sat Jul 06, 2013 1:23 pm

Hey guys, new here. I'm in the process of changing my thinking from rational to lsat logical.

Here are two made up "if/then" scenarios with contrapositves:

If you add 2 + 2 then you get 4. Contrapositive: If you don't get 4, then you didn't add 2 + 2.

Next, which is irrational to me:

If you get 4 then you added 2 + 2. Thus, CP would be: If you don't add 2 + 2, then you didn't get 4.

My brain says "well 3 + 1 = 4 so this can't be true". But in terms of lsat logic it has to be true based on the stimulus?

Let me know if my though process is off on this or if I am making any mistakes!

magickware
Posts: 359
Joined: Sun Nov 04, 2012 1:27 pm

Re: Basic conditionals

Postby magickware » Sat Jul 06, 2013 1:42 pm

Conditional statements are self-contained.

If I got an A, then I must have studied a lot.

A->studied a lot.
-studied a lot->-A

In all reality, there could have been other factors that influenced whether I got an A or not. However, in this specific conditional statement, the only thing that is required for me to get an A is me studying a lot.

I could instead write-

If I got an A, then I must have cheated.

A->cheated
-cheated->-A

And it's still perfectly valid.

Or

If I got an A, then I must be psychic and read the minds of the teacher and knew all the answers already.

A-> " "
- " "->-A

And so on and so forth.

Now, you could of course account for reality and make the following conditional-

If I got an A, then I must have either studied a lot, or cheated, or be able to read minds.

A-> studied a lot or cheated or able to read minds.

-studied a lot and -cheated and -able to read minds->-A
Last edited by magickware on Sat Jul 06, 2013 1:49 pm, edited 1 time in total.

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Balthy
Posts: 668
Joined: Sat Apr 03, 2010 12:28 pm

Re: Basic conditionals

Postby Balthy » Sat Jul 06, 2013 1:47 pm

How dare you distinguish between being rational and "lsat logical." The LSAT is the epitome of thinking rationally.

You're thinking, I think, about the difference between an argument being sound and valid. Here: http://www.iep.utm.edu/val-snd/

Fortunately, the LSAT does not ever ask you to determine an argument's soundness.

kaiser
Posts: 2940
Joined: Mon May 09, 2011 11:34 pm

Re: Basic conditionals

Postby kaiser » Sat Jul 06, 2013 1:48 pm

tke1600 wrote:Hey guys, new here. I'm in the process of changing my thinking from rational to lsat logical.

Here are two made up "if/then" scenarios with contrapositves:

If you add 2 + 2 then you get 4. Contrapositive: If you don't get 4, then you didn't add 2 + 2.

Next, which is irrational to me:

If you get 4 then you added 2 + 2. Thus, CP would be: If you don't add 2 + 2, then you didn't get 4.

My brain says "well 3 + 1 = 4 so this can't be true". But in terms of lsat logic it has to be true based on the stimulus?

Let me know if my though process is off on this or if I am making any mistakes!


Well, it doesn't make sense because that conditional isn't true (in that it isn't a sound conditional statement in the real world). Conditional relationships are supposed to be reflections of real word phenomena (not causation, but correlation of phenomena). But of course, you can make up any silly thing you want and call it conditional if the structure works, but as you can see, intuitive reasoning goes out the window when you do that. I think you are much better off using sound conditionals that don't get you sidetracked.

I'm guessing you made this up yourself?

User avatar
tke1600
Posts: 9
Joined: Wed Jul 03, 2013 9:30 pm

Re: Basic conditionals

Postby tke1600 » Sat Jul 06, 2013 2:05 pm

superdingle2000 wrote:How dare you distinguish between being rational and "lsat logical." The LSAT is the epitome of thinking rationally.

You're thinking, I think, about the difference between an argument being sound and valid. Here: http://www.iep.utm.edu/val-snd/

Fortunately, the LSAT does not ever ask you to determine an argument's soundness.



Yes, I was thinking in terms of sound/unsound or valid/invalid. Thanks for the article. Really helped!




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