Is this a Logical argument??

Question

I'm taking a intro Logic course in University and this is one of the questions. I just want to make sure I'm not out in left field here..


North Korea lacks strong diplomatic ties with the United States.(~p) If diplomatic ties were strong (p), the U.S. would have a good chance of persuading them to negotiate away their nuclear weapons program.(q) So the U.S. doesnt have much of a chance of persuading North Korea to negotiate away their nuclear
weapons program. (~q)

Now, I reduced this argument down to a sentential language and this is what I came up with...

(p>q)
~p
--------
~q

Now, I know this is denying the antecedent, but I cannot come up with anything else....

Is it still a valid argument??

Answer 1

Simply because P leads arguably to Q,
it does not follow that lacking P (or -P), Q is less likely.
Q may have many sources of success, among them P, but not exclusively P.

(For example, if the US threatened nuclear annihilation within 2 weeks unless N. Korea ceased all weapons programs, it may be persuasive even though there were no diplomatic relations.)

Answer 2

As you already know, one cannot deny the antecedent or affirm the consequent and still have a logically valid argument. This is simply modus ponens, modus tollens stuff. So, the argument (as you have stated it) is not valid. The form should be "p > q, ~q, therefore ~ p." I think the problem above is your denial of p. P should refer to the "if" part of the conditional, not to the part about North Korea lacking strong diplomatic ties with the USA.

Answer 3

Not valid. Here's a simpler example to see why an argument of that form is not valid:

If I become a doctor, then I will make a lot of money.
I won't become a doctor.
Therefore I won't make a lot of money.

Pretty obvious that it's invalid.

Answer 4

This is exactly why everyone with an IQ over 20 hates Logic. I am 50 years old and have NEVER, ever had to use Logic, calculus or had to diagram a damn sentence.

Answer 5

You make me very glad that there are so many people in this world that are smarter than me...I have no clue what all the p's and q's are for, but I'm glad you're minding them! :) OH, and without all the other mumbo jumbo, I think the point is valid...you can't convince someone who doesn't like you to do something they don't want to do!

Answer 6

I like what you're trying to do. but, there is no logic in this. In fact, does logic make any sense at all? ever? can you, for instance, explain logically that you have a favourite color?

Answer 7

http://en.wikipedia.org/wiki/Contrapositive

Answer 8

No, it isn't valid.
p>q does not necessarily entail -p > -q.

Answer 9

idk