Modus Tollens

Modus Tollens

A logical argument of the form:
If P, then Q.
Latin:
removing by taking away.

Modus tollens Logic:

If P, then Q
Not P is true
Therefore Not Q is true
Using if A, then B, we have:
A = Not P and B = Not Q

P = antecedent and Q = consequent.
If antecedent = false, consequence = false.

Modus tollens Notation:

!P → !Q

Truth Table Modus tollens:

The fourth line of the table below shows Modus tollens

P	Q	P → Q
T	T	T
T	F	F
F	T	T
F	F	T