Hypothetical Syllogisms- Conditional Arguments

Hypothetical syllogisms (conditional arguments) can have two valid and two invalid structures. The two valid structures are affirming the antecedent (modus ponens) and denying the consequent (modus tollens). The two invalid structures, or fallacies, are denying the antecedent and affirming the consequent. Determine if the arguments below are valid or invalid and what form they take. The first one has been done for you.
(NOTE: The term "modus pollens" has been used in some texts as a version of "modus ponens." For the purposes of this exercise, "modus ponens" will be used.)SAMPLE: Chris and Nick would be very happy if the Browns beat the Steelers. The Browns did beat the Steelers, so Chris and Nick are very happy, indeed.Valid Modus Ponens (Affirming the Antecedent)1. Madeline must have known the material for the test, because if a person knows the material, that person will always get an A, and Madeline was one of the students that got an A.2. Anastasia believes that if she treats people honestly and with an open mind, she will have diverse friendships. She is honest and open-minded and has friends all over the world.3. Roberto thought that if he worked very hard, his boss would give him a raise or a promotion. He made sure she noticed him, but she did not give him a raise or promotion. He thought he must not have worked hard enough.4. "I'm still eating too much ice cream," lamented George. "My waist measurement is the same as it was six months ago. I know if I didn't eat so much ice cream, I would reduce my waist size."5. The good way to make sure we pay fewer taxes is to elect conservatives. We must not have elected enough conservatives, because we are paying more taxes.6. If my neighbor were a decent human being, he wouldn't let his tree leaves fall onto my property. But he's not a decent human being, so we get to clean his tree leaves as well as ours.7. If I could only understand the concept of hypothetical syllogisms, I would get an A in class. Hurray! I got an A in class, so I must have understood the concept of hypothetical syllogisms.More information on this topic can be found here. This message has been edited by AdminPhat, 04-29-2005 02:38 AM

I've been thinking about your recent posts and I still, for the life of me, figure out where you want us to go with this.

Hey HT. I edited the topic and plopped it here! Now on to your examples....
1. Madeline must have known the material for the test, because if a person knows the material, that person will always get an A, and Madeline was one of the students that got an A.2. Anastasia believes that if she treats people honestly and with an open mind, she will have diverse friendships. She is honest and open-minded and has friends all over the world.3. Roberto thought that if he worked very hard, his boss would give him a raise or a promotion. He made sure she noticed him, but she did not give him a raise or promotion. He thought he must not have worked hard enough.

Where do we usually go with our posts? Skipping merrily down the path away from boredom...on to the golden rainbow of wisdom and happiness! Live large!

1. Invalid. Affirming the consequent
2. Valid. Affirming the antecedant
3. Valid. Denying the consequent
4. Valid. Denying the consequent
5. Invalid. Denying the antecedant
6. Valid. Denying the consequent
7. Invalid. Affirming the consequent.(You could have cheated the test. )Maybe you're promoting education??? What's my score teach?This message has been edited by mike the wiz, 04-29-2005 05:34 PM