Modus Ponens or Modus Tollens

I am confused by these. Here is the problem:

For each of the following pairs of statements, use Modus Ponens or Modus Tollens to fill in the blank line so that a valid argument is presented.

a) If Janice has trouble starting her car, then her daughter Angela will check Janice's spark plus.

Janice had trouble starting her car.

∴ ___________________________________

b) If Brady solved the first problem correctly, then the answer he obtained is 137.

Brady's answer to the first problem is not 137.

∴ ___________________________________

c) If this is a repeat-until loop, then the body of this loop is executed at least once.

_____________________________________

∴ The body of the loop is executed at least once.

d) If Tim plays basketball in the afternoon, then he will not watch television in the evening.

_____________________________________

∴ Tim didn't play basketball in the afternoon.

Here is what I have:

a) Her daughter Angelawill check Janice's spark plugs

b) Brady did not solve the problem correctly

c) This is a repeat-until loop

d) Tim watched television in the evening

I'm just not sure how to write these using Modus Ponens or Modus Tollens. Confusing.

Re: Modus Ponens or Modus Tollens

Quote:

Originally Posted by

**rhymin** For each of the following pairs of statements, use Modus Ponens or Modus Tollens to fill in the blank line so that a valid argument is presented.

a) If Janice has trouble starting her car, then her daughter Angela will check Janice's spark plus.

Janice had trouble starting her car.

∴ ___________________________________

b) If Brady solved the first problem correctly, then the answer he obtained is 137.

Brady's answer to the first problem is not 137.

∴ ___________________________________

c) If this is a repeat-until loop, then the body of this loop is executed at least once.

_____________________________________

∴ The body of the loop is executed at least once.

d) If Tim plays basketball in the afternoon, then he will not watch television in the evening.

_____________________________________

∴ Tim didn't play basketball in the afternoon.

Here is what I have:

a) Her daughter Angelawill check Janice's spark plugs

b) Brady did not solve the problem correctly

c) This is a repeat-until loop

d) Tim watched television in the evening

I'm just not sure how to write these using Modus Ponens or Modus Tollens. Confusing.

I am really confused too. Are you saying that you don't know which is which?

You have the correct answers for the 'blanks'. So what is your question?

Re: Modus Ponens or Modus Tollens

Well the textbook said to use Modus Ponens or Modus Tollens to fill in the blank, which should look something like this:

[p ^ (p → q)] → q

or

p → q

¬q

______

∴¬p

But, I'm not quite sure how exactly to write these out.

Re: Modus Ponens or Modus Tollens

Quote:

Originally Posted by

**rhymin** Well the textbook said to use Modus Ponens or Modus Tollens to fill in the blank, which should look something like this:

[p ^ (p → q)] → q

or

p → q

¬q

______

∴¬p

But, I'm not quite sure how exactly to write these out.

I really think that you are over-thinking this question.

As far as I am concerned, I taught this for over forty years, you have completed the question correctly.

You have correctly applied the rules.

Now, I am not your instructor. So I cannot be sure what you mean,

Re: Modus Ponens or Modus Tollens

Okay thank you. I guess I was over thinking it. I just got confused because the examples go very in depth with the "p, q, ∴, →, ¬, etc." symbols and letters and it is very hard for me to follow.