Formal Logic Help

*Ari*
Posts: 47
Joined: Sun Dec 05, 2010 1:20 am

Formal Logic Help

Postby *Ari* » Fri Jan 14, 2011 7:34 pm

Hi,

Just a quick reminder, as I can't remember for the life of me. Can you get the contrapositive of "most" statements? I am weary because I remember "most" statements are a non-reversible term, and it's only "some" "all" statements that can be reversed.

For instance,

"Most successful entrepreneurs work at least 18 hours a day, and no one who works at least 18 hours a day has time for leisure activities. But all happy entrepreneurs have time for leisure activities."

SE ->(Most) 18 -> ~L -> ~HE

What would the contrapositive of this statement be?

HE -> L -> ~18 ->(MOST!?) ~SE

Cheers.

bhan87
Posts: 850
Joined: Mon Mar 12, 2007 8:08 pm

Re: Formal Logic Help

Postby bhan87 » Fri Jan 14, 2011 7:38 pm

*Ari* wrote:Hi,

Just a quick reminder, as I can't remember for the life of me. Can you get the contrapositive of "most" statements? I am weary because I remember "most" statements are a non-reversible term, and it's only "some" "all" statements that can be reversed.

For instance,

"Most successful entrepreneurs work at least 18 hours a day, and no one who works at least 18 hours a day has time for leisure activities. But all happy entrepreneurs have time for leisure activities."

SE ->(Most) 18 -> ~L -> ~HE

What would the contrapositive of this statement be?

HE -> L -> ~18 ->(MOST!?) ~SE

Cheers.


You're diagramming "no one" incorrectly. No A's are B's. is actually A -> ~B

SE most 18
18 -> ~LE
__________
SE most ~LE

Also, no you can't take the contrapositive of a most statement

Hope this helps!

*Ari*
Posts: 47
Joined: Sun Dec 05, 2010 1:20 am

Re: Formal Logic Help

Postby *Ari* » Fri Jan 14, 2011 7:42 pm

bhan87 wrote:
*Ari* wrote:Hi,

Just a quick reminder, as I can't remember for the life of me. Can you get the contrapositive of "most" statements? I am weary because I remember "most" statements are a non-reversible term, and it's only "some" "all" statements that can be reversed.

For instance,

"Most successful entrepreneurs work at least 18 hours a day, and no one who works at least 18 hours a day has time for leisure activities. But all happy entrepreneurs have time for leisure activities."

SE ->(Most) 18 -> ~L -> ~HE

What would the contrapositive of this statement be?

HE -> L -> ~18 ->(MOST!?) ~SE

Cheers.


You're diagramming "no one" incorrectly. No A's are B's. is actually A -> ~B

SE most 18
18 -> ~LE
__________
SE most ~LE

Also, no you can't take the contrapositive of a most statement

Hope this helps!


I'm slightly confused. I did diagram "no one" as A -> ~B

But, indeed! It answers my questions about the ability to take contrapositives. I can't believe I haven't had to determine that prior.

*Ari*
Posts: 47
Joined: Sun Dec 05, 2010 1:20 am

Re: Formal Logic Help

Postby *Ari* » Fri Jan 14, 2011 7:42 pm

*Ari* wrote:
bhan87 wrote:
*Ari* wrote:Hi,

Just a quick reminder, as I can't remember for the life of me. Can you get the contrapositive of "most" statements? I am weary because I remember "most" statements are a non-reversible term, and it's only "some" "all" statements that can be reversed.

For instance,

"Most successful entrepreneurs work at least 18 hours a day, and no one who works at least 18 hours a day has time for leisure activities. But all happy entrepreneurs have time for leisure activities."

SE ->(Most) 18 -> ~L -> ~HE

What would the contrapositive of this statement be?

HE -> L -> ~18 ->(MOST!?) ~SE

Cheers.


You're diagramming "no one" incorrectly. No A's are B's. is actually A -> ~B

SE most 18
18 -> ~LE
__________
SE most ~LE

Also, no you can't take the contrapositive of a most statement

Hope this helps!


I'm slightly confused. I did diagram "no one" as A -> ~B

But, indeed! It answers my questions about the ability to take contrapositives. I can't believe I haven't had to determine that prior.

Also thanks! I appreciate the help.

bhan87
Posts: 850
Joined: Mon Mar 12, 2007 8:08 pm

Re: Formal Logic Help

Postby bhan87 » Fri Jan 14, 2011 7:47 pm

Whoops, I misread your post!




Return to “LSAT Prep and Discussion Forum”

Who is online

Users browsing this forum: No registered users and 4 guests