## Needhelpp101 2 years ago Determine if the argument is valid or invalid. Give a reason to justify answer. If it is cold, then you need a coat. You do not need a coat. ∴ It is not cold.

1. kt7779

invalid

2. zugzwang

It's actually valid.

valid

4. kt7779

oh

5. zugzwang

TYPO lol if p then q not q therefore not p THIS is the valid one, sorry

6. zugzwang

Modus Tollens*

7. Needhelpp101

thanks Guys :)

8. kt7779

yep

9. zugzwang

10. Needhelpp101

yeah

11. zugzwang

Well, what does it mean if p implies q? It means either p is false, or q is true, right? Because if p is not false, or p is true, it automatically implies q is true.

12. Needhelpp101

yeah

13. zugzwang

So p is false or q is true. At least one of these must be true, right?

14. zugzwang

But you also have the assumption q is false (You do not need a coat)

15. Needhelpp101

yep

16. zugzwang

p is false OR q is true. At lease one of these statements is true, and it's NOT the second statement, because we assumed q is false. Then it must be the case that the first statement is true (p is false) or (It is not cold)

17. Needhelpp101

ty Zug <3

18. zugzwang

anytime