Re: Post questions and comments here!

[Admin]

You are welcome and encouraged to use arguments from movies and TV shows. This particular argument seems invalid to me. If it is an enthymeme, what would the missing premises have to be to make it valid?
Monica

[LordAubrey]

Okay, this is a very silly question and I anticipate some very odd looks from not only the classmates but perhaps the teacher. And anyone else looking over the shoulders who understand the portfolio assignment.

But my argument that I am working on is actually a debate over the relationship status of non-existent alien characters. However, its essentially something that people are very bitter and stubborn over.

Is this still acceptable? It is a logical procedure and something I am very interested in. If I can't, I will go forward with something a little more close to home(and by that, I mean Europe. Sorry, America!) But I can't help but be drawn to fight against the argument of "Nepeta can't show any interest in Eridan because she called him a creep! And he is a creep! Its impossible, abloobloobloo ;_;"

[Admin]

Here is a gem from Stephen Bond, a PhD student in Ireland:

"An Ad hominem is 'You are an ignorant person, therefore your arguments are [weak].'"

Put that way, it is more clearly a fallacy! I recommend his blog post on the subject: plover.net/~bonds/adhominem.html

Bond offers examples of people in chat rooms wrongly claiming to have been subjects of ad hominem attacks. It is quite enjoyable and illuminating, but beware of strong language.


I also recommend this article in Scientific American:
www.sciam.com/article.cfm
May, 2008 Scientific American “Character Attacks: How to Properly Apply the Ad Hominem” By Yvonne Raley (http://www.sciam.com/article.cfm?id=character-attack)
Raley writes that attacks on character, "can be legitimate when a character critique is directly or indirect­ly related to the point being articulated.”

Be careful, however. Raley is not as precise with language as Bond is. She does not use the word "valid" in our technical sense, for example.

[Monica]

Conditional Proof

The method of conditional proof is a strategy for obtaining conditionals. It involves making a hypothetical assumption, showing what would follow from that assumption, and then asserting that if the assumption were true, then the consequent would follow.

Please note: the final product of the method of conditional proof is always a conditional.


Thus, for example:

1. P --> Q
2. (R v S) --> ~Q / P --> ~R
Indent 3. P ACP
Indent 4. Q 1, 3 MP
Indent 5. ~~Q 4 DN
Indent 6. ~(R v S) 2, 5 MT
Indent 7. ~R • ~S 6 DM
Indent 8. ~R 7 Simp
9. P --> ~R 3-8 CP

When using the conditional proof strategy you must keep a couple of things in mind:
(1) The conditional that you’ll end up with will always have the assumed statement as antecedent, and the final derived statement of the sub-proof as consequent; thus, make sure that you always assume the antecedent of the conditional that you’re trying to obtain. For example:

1. ~A v (B • C) / (B • ~C) --> ~A
Indent 2. B • ~C ACP
Indent 3. ~C 2 Com, Simp
Indent 4. ~B v ~C 3 Add, Com
Indent 5. ~(B • C) 4 DM
Indent 6. ~A 1, 5 Com, DS
7. (B • ~C) --> ~A 2-6 CP


(2) Once you have finished a sub-proof it is closed off from the rest of the proof. You may not use any of those lines again. For example:

1. (P v Q) --> R / (P --> R) • (P v Q)
Indent 2. P ACP
Indent 3. P v Q 2 Add
Indent 4. R 1, 3 MP
5. P --> R 2-4 CP
6. (P --> R) • (P v Q) 3, 5 Conj WRONG

This argument is invalid; but if we use line 3 after the sub-proof has been closed we can seem to ‘prove’ it anyway. The conditional proof strategy wouldn’t be very helpful if it let us ‘prove’ invalid arguments like this.


Practice:

7.5, I: 5)
1. A --> ~(A v E) / A --> F


8. 1. P --> (Q v R)
2. (P --> R) --> (S • T)
3. Q --> R / T

11) 1. M --> (K --> L)
2. (L v N) --> J / M --> (K --> J)


14) 1. (F • G) --> H
2. F --> G / F -->H

15) 1. C --> (D v ~E)
2. E --> (D --> F) / C --> (E --> F)



20) 1. A -->[B --> (C • ~D)]
2. (B v E) --> (D v E) / (A • B) --> (C • E)

[Monica]

26. H -> U / H-> (U v T)

Well, if you have a -> and are stuck, you can always do material implication. That will give you a wedge, and maybe you can do something with that. Also, there is a completely new sentence letter in the conclusion (T), so we'll probably have to add it at some point.

[Linh]

I have problem when solving 7.4, III: 26.
Can I have any suggestion or idea?

[Admin]

In the middle of 7.3, Hurley writes:

"If your instructor permits it, you can combine commutativity and double negation with other inferences on a single line, as the following short proof indicates" (pg 373 in 10th Edition).

On Monday (7/25) we made a deal: your instructor will permit this move in your homeworks and on your quizzes if and only if the mode for Quiz 4 is 58, 59, or 60.

The results for Quiz 4:

mean (all the scores divided by the number of people) 50
median (the score in the middle) 59
mode (the score that shows up most often) 60

So the deal is on. Congratulations! You may use this short cut on your own written work (though we will continue to write out each step separately in class).

- Monica

[Admin]

You are invited and encouraged to use the SCCC Summer Integrated Water Projects as a source for some of your portfolios. Information is below. - Monica
--------

"“WITHOUT WATER WE HAVE NO LIFE, NO CULTURE, NO SOCIETY.”

- Jim Schultz



SmallWFPlogo.jpg





Integrated Water Projects

Wednesday, August 10th

9:00 to 11:30

Room #1110



Students from Communications and Sociology have been working together this quarter to develop social change projects around the global issue of water.

Groups will be presenting their work on Wednesday, August 10th from 9:00 until 11:30, in room #1110.

We would love to have you and your students stop by and experience an integrated assignment in action.



Hope to see you and your classes there, any questions feel free to ask Greg Hinckley or Marian Lyles."

[Admin]

Per request, I have compiled more specific grade targets for you to aim for.

These are for guidelines only and not a guarantee of grade!

I won't know for sure until the end of the quarter, but I will start with this general grade breakdown and then adjust it, so this should give you a general idea of what you can aim for on quizzes.

GRADE	TOTAL PTS.	AVERAGE QUIZ GRADE TARGETS:
		(85%)*	(100%)**
4.0 95%	500 pts	58 pts	55 pts
3.0 85%	440 pts	49 pts	47 pts
2.0 75%	400 pts	43 pts	41 pts
1.0 65%	345 pts	36 pts	33 pts
0.7 60%	330 pts	33 pts	31 pts

* Assuming 85% for HW, portfolio and participation
** Assuming 100% for HW, portfolio and participation

[Admin]

Here are some tips on strategy for proofs.

1. Look for repeated patterns (such as [(~S v T) v ~M] repeated in more than one premise somewhere).
2. Small sentences are your friend (e.g., A, ~R). Use them to "pry open" the compound statements.
3. Work backwards from the conclusion.
4. If there is a letter in the conclusion that is not in the premises, you will probably have to use the ADDITION rule at some point. (This especially applies to the last problem on the homework).

- Monica

[Admin]

8/1
Read Ch. 7.3-7.5 **CHANGED**
HW 5:
7.3.III: 5, 11, 27; IV: 8. 7.4.III: 3, 8, 26.
7.5.I: 2, 9, 18 (CP proofs only); II: 2 (CP proof only).

8/8
Read Ch. 7.5-7.6 **CHANGED**
HW 6:
7.5.I: 2, 9, 18 (CP proofs only); II: 2 (CP proof only).
7.6.I: 1, 8, 9; II: 5.

8/15
Read Ch. 3.1-3.5 **CHANGED**
Read only Fallacies #: 4,6,9,11,12,13,14,15,16,17
HW 7:
3.1.I: 6, 8, 9. 3.2.I: 2, 17; II: 3, 5, 8.
3.3.I: 1, 6, 12; II: 1, 5, 9.
3.4.I: 17, 18; II: 1, 2, 3, 4.

[Linh]

I mean HW 6 due on Moday, 8 / 8, I don't know why it appears an icon there...

[Linh]

Thank you Monica.

Hi Aubrey,

This is the list of homework:

HW 4 (due Monday 7/25):
7.1: III/ 2,8,11,20; IV/ 2,6;
7.2: III/ 8, 17, 21, 27

HW 5: (due Monday 8/1):
7.3: III/ 5, 11, 27; IV/ 8
7.4: III/ 3, 8, 26
7.5: I/ 2,9,18 (CP proofs only); II/ 2 (CP proofs only)

HW 6 (due Monday 8/: TBA

HW 7: (due Monday 8/15):
3.1: I/ 6,8,9
3.2: I/ 2,9,17; II/ 3,5,8,9
3.3: I/ 1,6,12,14; II/ 1,2,5,9
3.4: I/ 15,17,18; II/ 1,2,3,4

[Admin]

Interesting question! This is an issue of convention/rules only, not of logic.

DS is the name of the form when the other premise is a negation of the the Left-hand disjunct.

If the Right-hand disjunst is being negated instead, the argument is still valid, but we cannot use the DS rule, according to the rules we are learning in Hurley's text.

Bring your question to class, and we can talk about it some more.

- Monica

[Linh]

I have a question in the yellow sheet.
The answer key said that number 9 is valid, but not DS form.
If "p v q" is equivalent to "q v p" ( I read somewhere in the book :p), then number 9 has the form:

q v p
tilde p
Conclusion is q

While DS form is:

p v q
tilde p
Conclusion is q

So, does "DS" exist in the first form with "q v p", or "DS" only has the "p v q" form?

[LordAubrey]

A question from myself as well!

Would it be possible to have a list of the homework assignments(As in the pages/problem numbers) posted somewhere on here?

I am a little forgetful and tend to lose papers rather easy, and it would be useful to have them accessible for when I happen to leave the sheet that has the homework somewhere I can't find it.

(If this is already in place somewhere, though, could I get pointed in that direction? Apologies for my ridiculous levels of forgetfulness.)

[Monica]

Good question! The worksheet I sent today on 6.3 is just for practice and studying -- it is not homework.
Monica

[Linh]

Hello,

I have a question.
The attached file you sent us by email, is it a homework or just an extra work for us to practice?

Linh

[Admin]

Post questions on this forum.

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