P: A–most–XP: not B → not AC: ?

Mehran May 31, 2017

@DennisGerrard remember the two rules for making a deduction with a Quantifier statement:

(1) Sufficient & Necessary Statement (the only exception is two "Most" statements with the left side in common).

(2) The Quantifier shares the sufficient condition in common with the S & N statement (i.e. the arrow must point away from the Quantifier statement).

Here "A" is what is in common but to get "A" we need the contrapositive of P2:

A ==> B

To combine these statements, we need to reverse P1 and "most" becomes "some":

X-some-A

X-some-A ==> B

To conclude:

X-some-B
B-some-X

Watch the video lesson on Quantifiers if you are still struggling with these concepts.

You just need to commit these rules to memory. Hope that helps!

DennisGerrard June 3, 2017

In the case you described, if X most A, A==>B, we can't conclude X most B,right?

Mehran June 6, 2017

@DennisGerrard no, you could.

X-most-A ==> B

X-most-B
B-some-X

Hope that helps! I would recommend watching our video lesson on Quantifiers for a more in-depth review of these concepts.