Thread: question about validating an argument

I am trying to detrmine whether this argument is valid or not:

p → q
∼p
———
∴∼q

I did not see this as modus ponens or modus tollens.

But I described it as:

p: I walk my dog
q: he is happy

p → q: if I walk my dog he is happy
~p: I did not walk my dog

therefore

~q: he is not happy

This is not valid according to the table there could be two different outcomes.

is this correct?

p|q|p → q| ~p|~q

T|T|T |F |F
T|F|F |F |T
F|T|T |T |F
F|F|T |T |T

Is this correct?

If now please explian how to prove (valid) or (invalid)?

Let and .
If you have do you have

yes

Originally Posted by robasc

yes

Yes what?

You have

yes it is false

Well then the argument is not valid.

this is known as a fallacy, denying the antecedent correct?

Yes. What is the point of all this?

I am double checking myself to make sure I am understanding the material correctly?