MODUS TOLLENS

Sentence pattern:

if [sentence 1] then [sentence 2]
not [sentence 2]

Therefore, not [sentence 1]		 Form:
Example:




If Rexin contains morphine. then it is habit forming.

It is not the case that it is habit forming.
..
Therefore, it is not the case that Rexin contains morphine..		 Example symbolized:
Following the logical convention of letting a single letter represent an atomic sentence:

R = Rexin contains morphine.
H = It is habit forming..

And replacing 'if...then...' with a symbol for implication: >
And replacing 'it is not the case' with: ~


R > H
~H
-----------

~R
 Example of MT:


~(S > H) > ~(F + ~P)
(F + ~P)
---------------------
~~(S > H)

 Application:

1. ~M > (~K > M)
2. ~M             ~~K 
3. ~K > M      1, 2 MP
4. ~~K         2, 3 MT