Question

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.

Answer 1

I know that it is Valid but I need to justify why... conjunction?

Answer 2

why not use the table?

Answer 3

not good w/ the table

Answer 4

valid by the law of contraposition.
the law of contrapoisiton states:
if a implies b, then not b implies not a.
the statement and its contrapositive are equivalent.??????

Answer 5

If it is cold, then you need a coat.
You do not need a coat.
It is not cold.
:.You are in a hot tub.

Answer 6

ummm that was not a good answer

Answer 7

lol

Answer 8

I am no so sure but it's a contrapositive statement,but I still believe it's better to use the table.you can't remember all the rules

Answer 9

no

Answer 10

ill look into it

Answer 11

p implies q,-q therefore -p

Answer 12

use the table!table!
and then
[(p implies q)and(-q)] implies -p shall be a tautology.

OR
using just your knowledge of logic
p implies q is only F when p is T and q is F
and that notes -P is T
so F implies T is T and in all other cases it's T so it's tautology meaning it's VALID

Answer 13

thanks

Answer 14

so you got it?

Answer 15

yes...im going to read further into it and practice until it becomes more clearer to me

Answer 16

Ok!break a leg.But TABLE IS VERY IMPORTANT.work hard on that it makes life is easier.

Answer 17

life easier. D:

Answer 18

yes im sure ill get it just been a long day of work....mind may be too cluttered

Answer 19

OK!be safe.