Mathematics does not
lie, if the context is taken into account.
Modus
putting ponens (or modus ponens, MP) is a valid argument form and an inference
rule in propositional logic. In the MP it is part of a conditional (if P, then
Q), the first or antecedent P is given or affirmed, and it is concluded that
the consequent or Q is true. The statement is: "If P implies Q,
and P is true, then Q is also true."
If P, then Q. P. Therefore,
Q. (Affirmation of the antecedent)
The
invalid fallacy or reasoning:
If P, then Q. Q.
Therefore, P. (Affirmation of the consequent)
Consider
the following situation. Juan, on the way back home, passes an electrical
appliance store that displays several models of flat-screen TVs. Thinking about
the 2018 World Cup of Russia, he pauses for a moment to contemplate the
spectacular images in a colorful model. The seller notices his interest, tells
him that it costs $ 1,000 but if he buys at that moment the television only has
to pay $. 750. So, Juan will save $ 250.
Question 1. If John buys the
television, what would be the valid argument?
First:
If I pay $ 750 for the TV, then I save.
I
pay $ 750 per TV.
Then,
I'm saving.
Second: If I pay $ 750
for the television, then I save,
I'm saving.
Then, I paid only $
750 for the TV
Question 2. How much does Juan
save? (Detail: Juan did not have or had the intention to buy the television,
the passage through the store was fortuitous)
