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# Proving logic

Sat 4 Mar, 2017 01:16 pm
Hi everyone, does anyone know what the answers to these questions would be? I am really struggling with this particular assignment, so would appreciate any help or explanations. I have to prove that the following statements are valid in proven logic. Thank you
¬ = not → = if/ then
¬ ¬(P & Q) : ¬ ¬ (Q & P) (6)
¬ P → ¬Q: Q → P (6)
: (P →Q) → (¬Q →¬P) (5) Principle of transposition
Q → R : (¬Q →¬P) →(P →R) (9)
(P & Q) →¬R : R →(P →¬Q) (11)
P: [(¬(Q → R) →¬P)] →[( ¬R →¬Q)] (9)
P, ¬Q: ¬ (P →Q) (6)
P, ¬P : Q (8)
: ¬P → (P →Q) (10) Law of Dun Scotus
P → ¬P : ¬P (11)
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Type: Question • Score: 5 • Views: 1,545 • Replies: 45
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cicerone imposter

0
Sat 4 Mar, 2017 11:54 pm
@miafuller,
Real human problems are not constructed of formulas.
Reality is how the individual perceives it subjectively.
Your values are not the same as others. That's the reality of life.
Philosophy is understanding reality; that's logic.
Krumple

2
Sun 5 Mar, 2017 12:14 am
@cicerone imposter,
cicerone imposter wrote:

Real human problems are not constructed of formulas.

Sure they are. Even recipes!

cicerone imposter wrote:

Reality is how the individual perceives it subjectively.

There are objective experiences though or else we wouldn't even be able to communicate.

cicerone imposter wrote:

Your values are not the same as others. That's the reality of life.

Are there no objective values?

cicerone imposter wrote:

Philosophy is understanding reality; that's logic.

I though philosophy was the practice of pointing out reality to everyone who doesn't understand it. Why are there philosophers if reality is supposedly so clear?

The human mind can hold an untruth as truth and a truth as untrue. The mind doesn't care about being true to reality (at least not in a general sense, some care more than others)

This was only a practice in hair splitting, so dont mind me.
Blickers

1
Sun 5 Mar, 2017 12:15 am
@miafuller,
Tough one. Don't know if anyone here is into logic like that.

If you don't get an answer, why not try a message board devoted to philosophical topics like Philosophy Forums. Good luck.
fresco

2
Sun 5 Mar, 2017 03:45 am
@Krumple,
OFF TOPIC
Quote:
There are objective experiences though or else we wouldn't even be able to communicate.

No....there are experiences which we agree about, (largely due to our common physiology), which we call 'objective' !
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ON TOPIC
Obviously this has little to do with standard 'Truth Table' proofs which are often requested here by philosophy students of uncertain mathematical ability.

The philisophical significance of such proofs or otherwise indeed involves the epistemological status of traditional (binary) logic per se, which has been questioned by the Post-Modernists for example.
fresco

1
Sun 5 Mar, 2017 04:47 am
@Blickers,
Not tough at all......This is 'Logic 101'. It requires the student to check corresondence of 'truth tables' or to apply validity methods such as 'backward fell swoop'. Obviously to do this homework here, even if we wanted to, would take far too much space.
0 Replies

layman

-2
Sun 5 Mar, 2017 05:33 am
@miafuller,
miafuller wrote:

Hi everyone, does anyone know what the answers to these questions would be? I am really struggling with this particular assignment, so would appreciate any help or explanations. I have to prove that the following statements are valid in proven logic. Thank you
¬ = not → = if/ then
¬ ¬(P & Q) : ¬ ¬ (Q & P) (6)
¬ P → ¬Q: Q → P (6)
: (P →Q) → (¬Q →¬P) (5) Principle of transposition
Q → R : (¬Q →¬P) →(P →R) (9)
(P & Q) →¬R : R →(P →¬Q) (11)
P: [(¬(Q → R) →¬P)] →[( ¬R →¬Q)] (9)
P, ¬Q: ¬ (P →Q) (6)
P, ¬P : Q (8)
: ¬P → (P →Q) (10) Law of Dun Scotus
P → ¬P : ¬P (11)

1) what does the colon mean?
3) is this supposed to be a series of separate problems, or are these all supposed to be implications of continuing assumptions which are merely added to the first (P implies Q, because two negatives make a positive) as it goes along?
0 Replies

izzythepush

2
Sun 5 Mar, 2017 08:07 am
@miafuller,

"Could it be daffodils?"
0 Replies

Fil Albuquerque

1
Sun 5 Mar, 2017 09:46 am
@fresco,
Why do we agree on those experiences ? Please provide a comprehensive explanation. Your solipsistic statements are inconsistent with agreement on anything...
0 Replies

cicerone imposter

1
Sun 5 Mar, 2017 10:14 am
@Krumple,
"Human problems" not food. Objective to the perceived. Do you believe in god or are you an atheist? What political party do you belong to?
Are you always correct in your perceptions?
0 Replies

cicerone imposter

1
Sun 5 Mar, 2017 10:23 am
@fresco,
fresco understands objective truth.
It's when truth conditions are met without bias.
0 Replies

cicerone imposter

1
Sun 5 Mar, 2017 10:35 am
@Krumple,
How does one "point out reality" to the masses?
0 Replies

Razzleg

1
Wed 8 Mar, 2017 04:27 am
@miafuller,
Y'know, it's funny, I just copy-and-pasted Mia's logic problem into google (because i sure as hell couldn't solve it, it's been more than 20 years since i took symbolic logic), and it became fun to track their attempts to seek answers on various websites. (The OP actually found the most helpful advice on reddit, which is a fact that is interesting in its own right...)

A lot of people on these here internets didn't know what the OP wanted to know, but only here did they receive the sort of bullshit, non sequitur parade of responses you folks offered. Here's a beakdown of this thread: OP asked logic question, Cicerone offered vacuous platitudes, Krumple made glib ontological hypotheses, fresco acted as if he knew what was going on but didn't actually help the OP, layman interjected without understanding the problem, izzythepush posted a meme, Fil challenged everybody in a vague sort of way, and finally Cicerone returned to challenge Fil for supremacy in the matter of ambiguous statements.

What are we doing here? And why are we calling it philosophy?
roger

2
Wed 8 Mar, 2017 05:21 am
@Blickers,
Blickers wrote:

Tough one. Don't know if anyone here is into logic like that.

If you don't get an answer, why not try a message board devoted to philosophical topics like Philosophy Forums. Good luck.

Well, dang. I thought that was the name of the forum that was hijacked by a2k about a decade ago and kind of blended into a2k. In fact, I thought that was where we got Krumple and Razzleg.
Fil Albuquerque

1
Wed 8 Mar, 2017 06:22 am
@Razzleg,
Excuse me Razzleg but where did I vaguely challenged everybody? I asked a very specific question to Fresco on his god damn habit of talking about agreement on every thread he jumps in. I didn't care with the fracking OP problem for a second nor tried to answer his bulshit lazy ass "do my home work for me"...By the way, what was vague about a very cut clear question to Fresco ? Why do we agree on some statements? Can you answer in his place perhaps?

...oh by the way, to bypass answering a Philosophical problem when we have reason to believe we should not answer it is a philosophical decision.

...what are we doing here?
Averages of the same stuff we do everyday!
You might as well ask what the Parlament in any country is doing the all freaking day...

Last but not least, given your criticism, why didn't you answer the OP and ruled by example, eh ?
0 Replies

fresco

1
Wed 8 Mar, 2017 06:52 am
The answer to those might want to know what 'agreement is ...it is 'social coherence and convergenence usually expressed in the form of verbal behaviour' or consequent mutual action This is the antithesis of a 'solipsistic position' because it places 'social interaction ' at the forefront of semantics.
I have nothing further to say on the matter' .Refer to Wittgenstein's dismissal of 'private language' if my point is not understood.
izzythepush

1
Wed 8 Mar, 2017 06:59 am
@Razzleg,
So it's not daffodils then? You learn something every day.
Fil Albuquerque

1
Wed 8 Mar, 2017 07:02 am
@fresco,
Nobody asked you what IS agreement for fracks sake, I have asked you WHY do people can agree? Which is a very interesting question indeed...What is the engine/mechanics for agreement given and according to your motto Truth is relative. How can people even debate among themselves without differing infinitely from each other to the point of not being able to have a talk. Your background frame theory allows for an infinite degree of relativism which statistically would render communication impossible, let alone agreement.

Your "conceptual ecosystem" is so deficient in establishing long shot relations that it has trouble understanding how relativism intertwines with infinity no doubts...

Post Scriptum - Let me make it easy for you, you don't believe in Ratios of any order yet your agreement requires one!
izzythepush

1
Wed 8 Mar, 2017 07:06 am
@Fil Albuquerque,
Fil Albuquerque wrote:

Nobody asked you what IS agreement for fracks sake,

I did. I consistently bombarded Fresco with inane and insistent pms demanding exactly that. In the end it was only the threat of a dry slap that made me back down.
0 Replies

Fil Albuquerque

1
Wed 8 Mar, 2017 07:21 am
How does one MECHANICALLY connect one person X given concept with another person vision of the concept in the first place?
...worse, how does the partner even arrives at an approximation of the concept with an infinite degree of freedom ? ...which is EXACTLY what lack of an absolute referent entails...

...its an absolute shame that someone with a philosophical education can't phantom just how far his understanding or cosmovision indulges in total Irrationality. This is the exact opposite of what Philosophy is all about!
0 Replies

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