# New Member with questions!

1. Philosophy Forum
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Fri 6 Jun, 2008 01:28 pm

Hello everyone, this is my first post here. I'm glad to find some place where I can talk with people interested in Philosophy too. I'm mainly interested in Logic though.

I did have a question though, I'm taking basic philosophy right now and our professor gave us some questions to go over. I am completely stumped on four of them. He gave us a sheet with 18 rules for inference and replacement.

we are supposed to prove the arguments as valid. I'm hoping someone can help explain this to me.
And Logic pro's in the room? Don't laugh, they're hard for me. :p

Anyhow, here are the problems I have

1:
[A [SIZE="5"]꜆[/SIZE] (B v C)] [SIZE="5"]꜆[/SIZE] (D [SIZE="5"]꜆[/SIZE] A)
~A
/∴ ~D

2:
A [SIZE="5"]꜆[/SIZE] B
/∴ A [SIZE="5"]꜆[/SIZE] ~(~B . ~C)

3:
~N [SIZE="5"]꜆[/SIZE] S
S [SIZE="5"]꜆[/SIZE] ~A
~A [SIZE="5"]꜆[/SIZE] ~V
/∴ V [SIZE="5"]꜆[/SIZE] (A . N)

4:
~W [SIZE="5"]꜆[/SIZE] ~F
~F [SIZE="5"]꜆[/SIZE] ~(E v A)
~E [SIZE="5"]꜆[/SIZE] S
P [SIZE="5"]꜆[/SIZE] A
/∴ ~W [SIZE="5"]꜆[/SIZE] (S . ~P)

VideCorSpoon

Fri 6 Jun, 2008 01:34 pm
@SteveP phil,
Welcome! Never hesitate to ask any questions!

I can help you through them if you want. But first, are you developing a proof or you just need the blank connectives? These proofs seem broken, like they are missing substantial parts of the overall problem. Write down the proofs the exact way your teacher wrote them down. Also, you may want to start a new thread in the logic section.

Also, you may want to tell your instructor there are 20 inference and replacement rules. But he/she may not count indirect and conditional proofs as rules.

SteveP phil

Fri 6 Jun, 2008 01:42 pm
@VideCorSpoon,
Wow, thanks for the quick reply.

What we were told to do is prove the arguments valid. We need to break down the problems using things such as Modes Ponens or DeMorgan's rule (to name a few).

and these problems are written down just as she wrote them, except I put the conclusion on a separate line - whereas she wrote them on the same line as the last string.

SteveP phil

Fri 6 Jun, 2008 01:50 pm
@SteveP phil,
It did occur to me that you might not be able to see all the special characters I put in there... I have a bunch of horshoe's and what-not. If you can't see them let me know.

btw, she DID Say we could use Conditional and Inconditional proofs as well.

VideCorSpoon

Fri 6 Jun, 2008 01:52 pm
@SteveP phil,

SteveP phil

Fri 6 Jun, 2008 01:55 pm
@VideCorSpoon,
We can create new lines using the 18 rules she gave us. And thats how we are supposed to do it. I just can't figure out where to start. Each line is number 1-? in order so I didn't think the numbering mattered.

SteveP phil

Fri 6 Jun, 2008 01:56 pm
@SteveP phil,
Ok, I see whats wrong. You're not seeing my special characters I put in.
Let me see if I can Upload them in a file.

VideCorSpoon

Fri 6 Jun, 2008 01:57 pm
@SteveP phil,
Ok, but still, create a new thread in the logic section.

SteveP phil

Fri 6 Jun, 2008 01:58 pm
@VideCorSpoon,
VideCorSpoon;15270 wrote:
Ok, but still, create a new thread in the logic section.

I don't have permission to.

VideCorSpoon

Fri 6 Jun, 2008 01:59 pm
@SteveP phil,
Ok, I'll start a new thread entitle "Logic Proof Help."

SteveP phil

Fri 6 Jun, 2008 02:00 pm
@VideCorSpoon,
VideCorSpoon;15272 wrote:
Ok, I'll start a new thread entitle "Logic Proof Help."

Thanks! I'll be there in a second!

Justin

Fri 6 Jun, 2008 08:55 pm
@SteveP phil,
SteveP;15271 wrote:
I don't have permission to.

Yes, you do have permission to. Welcome to the forums!

SteveP phil

Sat 7 Jun, 2008 12:34 am
@Justin,
Ah, thank you justin!

1. Philosophy Forum
2. » New Member Introductions
3. » New Member with questions!