![[dr. bob]](/dr-bob-sm.gif)
Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 17 to 41 of 41. Go back in thread:
Posted by alexandra_k on May 17, 2005, at 0:12:48
In reply to Re: couple more: » alexandra_k, posted by alesta on May 16, 2005, at 23:38:28
Posted by alexandra_k on May 17, 2005, at 0:37:16
In reply to Re: please do not post to me (nm) » alesta, posted by alexandra_k on May 17, 2005, at 0:12:48
... its not my 'semester long schoolwork'.
I wrote it.
It took me a while.
Because I wanted to try and see whether I could explain the concept of validity and invalidity to people with no formal training in logic.
Trying to explain things simply is an art...
It isn't one that I am very good at.
But I want to get better.I know a lot of people don't care.
That is fine.
I know a lot of people find it hard.
That is fine too.
Some people get it fairly easily first off...
Others have to work at a slower pace...
Still more have to work fairly hard to start with...
But everyone is capable of getting it in the end.Myself.
I had to work really really hard.
I thought that might be able to help me explain that to other people.
Just in case they are interested.If people aren't.
Then just ignore me.
If you don't feel able to do that...
Then take it over to admin
Like people do with Lou.
I am who I am.
Posted by All Done on May 17, 2005, at 0:54:31
In reply to Re: couple more: » Larry Hoover, posted by alexandra_k on May 16, 2005, at 22:48:40
Can I give it a try :)?
> (e) - VALID
> (P1) It is raining and it is wet
> _________________________________
> (C) It is raining
>
> (f) - INVALID
> (P1) Either it is raining or it is wet
> (P2) It is not raining
> _______________________________
> (C) It is not wet
>
> (g) - VALID
> (P1) Either it is raining or it is wet
> (P2) It is not wet
> ____________________________
> (C) It is raining
>
> (These are a little harder)
>
> (h) - VALID
> (P1) If it is snowing then I am cold
> (P2) I am not cold
> ____________________
> (C) It is not snowing
>
> (i) - INVALID
> (P1) If it is snowing then I am cold
> (P2) It is not snowing
> ___________________________
> (C) I am not cold
Posted by All Done on May 17, 2005, at 1:11:09
In reply to Re: in case anyone was wondering..., posted by alexandra_k on May 17, 2005, at 0:37:16
I've read logic puzzle books just for fun. I wonder if Larry has, too.
Even if I can't figure them out all the time (or maybe even most), I love the process of thinking it through and trying to figure out the right answer. I can get lost in my thoughts that way. It's a nice escape.
And when I know there's a right answer and I've figured it out...woohoo! Yeah, I'm a geek.
:)
Posted by Damos on May 17, 2005, at 1:37:42
In reply to Re: in case anyone was wondering..., posted by alexandra_k on May 17, 2005, at 0:37:16
Hey Alex,
I guess these were probably largely for my benefit and I really appreciate you taking the time and effort to post them. I'm just kinda sorry I haven't really had a chance to look at them before this. Even sorrier the thread kinda went south at the end.
Don't get enough brain exercise and look forward to working through your posts.
Thanks again, lots of love
Posted by alexandra_k on May 17, 2005, at 2:26:10
In reply to Re: couple more: » alexandra_k, posted by All Done on May 17, 2005, at 0:54:31
> Can I give it a try :)?
Of course...
And it turns out...
that you are a natural
:-)
Bingo.
Well done.I was kind of hoping...
Kind of hoping...
That if people got into this then I could show people how to construct formal proofs of validity.Then you should indeed be able to work out those logic puzzles :-)
The funny thing about logic is that it is
so hard to explain.
If people don't get it you have the urge to point.
And then to point HARDER.
But that doesn't really help someone see it.But most people can do it without understanding the *why*'s.
The *why*'s just tend to be more helpful than pointing harder.
:-)
:-)
:-)
Thank you so much.
Posted by alexandra_k on May 17, 2005, at 2:40:19
In reply to Thanks Alex , guess these were for my benefit » alexandra_k, posted by Damos on May 17, 2005, at 1:37:42
(((Damos)))
Take all the time you need.
And I promise most sincerely not to be offended if you think:
Logic!!!
AAAAAAAAAAAAAAAAAAAAAAAAAAAARGH.
And hate it.
Like most people.
:-)
Posted by alesta on May 17, 2005, at 13:57:55
In reply to Re: couple more: » alexandra_k, posted by alesta on May 16, 2005, at 23:13:02
Posted by Damos on May 17, 2005, at 16:57:05
In reply to Re: :-) You are wonderful Damos, posted by alexandra_k on May 17, 2005, at 2:40:19
I'm gonna be so good and just say 'thank-you'.
Okay, can I now say my brain aches.
c) invalid
d) valid
e) valid
f) invalid
g) Buggered if I know, valid I think
h) Hmmmm, valid?
i) InvalidI agonised over g) & h) and am still not convinced either way, but have resisted the temptation to look at Lar & All Done's posts just in case. It's so odd seeing arguements presented like this. Even odder to use logic in this way.
Have to admit to being more than a little confused for a while (still debating the answers with myself as I post this), but enjoyed the exercises.
Thanks,
(((Alex)))
Posted by 10derHeart on May 17, 2005, at 21:56:17
In reply to that went well.:) (nm), posted by alesta on May 17, 2005, at 13:57:55
Alesta,
I'm so confused.
I've reread several times, trying to see how Alex was taunting anyone. I can't for the life of me see it. Her post seemed innocent and neutral to me.
Is it when she asked if people were lost? I took that on its face, purely as a straight question, not putting anyone down or anything. As she stated, this stuff isn't commonly done and IS confusing. I assumed she genuinely wanted to know, so she could rephrase, help them, etc.
Is this just a huge misunderstanding? Or I am incredibly dense and have missed something?
I am more than willing to try and see it from another POV, if you feel like maybe explaining another way why you felt taunted...?
To me, your words and tone seemed a bit harsh, even hostile, and not supportive. I was so surprised. That seems completely unlike you, from all your wonderfully supportive threads I've seen here lately. :-( ??
This thread really bothered you, clearly. But I don't know why. I hate it when I don't *get* why a poster becomes upset about a thread. I learn so much more about how to coexist here with everyone when I do understand.
And the way this thread "went south," as Damos put it so well, well, it makes me very sad.
Because lately a few subjects I find fascinating or fun have run through my head. And I've been thinking to myself, "Wonder if this question, or subject, would be cool/fun/neat (sorry, my vocab is probably dating me) to post on social?" But I've hesitated, worried I'll seem foolish, or boring, or weird, or irritating. Much like the anxiety and doubts that grip me IRL from time to time.
Now I'm a bit more worried that I was right.
Feel free to ignore if rehashing this will lead to any violations of the board civility guidelines. I understand sometimes it's just better not to talk about stuff.
I just got so lost reading the dialog between you two. And sad, don't forget sad.
Posted by alesta on May 17, 2005, at 22:07:29
In reply to Alesta » alesta, posted by 10derHeart on May 17, 2005, at 21:56:17
10erheart,
in all honesty, i only read the first line of your post and stopped there. i want to just forget about this thread right now. i'm sorry i can't respond. but i just can't handle it right now. i have my reasons for my interpretations. that's all i have the energy to put forth. one more disagreement may just push me over the edge. (note my thread about severe depression/suicidal thoughts.) i hope you understand.amy
Posted by 10derHeart on May 17, 2005, at 22:18:10
In reply to Re: Alesta » 10derHeart, posted by alesta on May 17, 2005, at 22:07:29
Posted by gardenergirl on May 17, 2005, at 22:19:56
In reply to Re: (((alexandra))), posted by All Done on May 17, 2005, at 1:11:09
alexandra and laurie,
> I've read logic puzzle books just for fun. I wonder if Larry has, too.Oh lordy, me too! And the logic part of the GRE was my best score. And my favorite. They were much more like games than test items. MUCH better than the vocab stuff!
>
> Even if I can't figure them out all the time (or maybe even most), I love the process of thinking it through and trying to figure out the right answer. I can get lost in my thoughts that way. It's a nice escape.
>
> And when I know there's a right answer and I've figured it out...woohoo! Yeah, I'm a geek.
>
> :)Geeks rock! :)
gg
Posted by alexandra_k on May 17, 2005, at 23:22:08
In reply to Re: couple more: » Larry Hoover, posted by alexandra_k on May 16, 2005, at 22:48:40
Your answers are correct :-)
Some of them were hard.
I get what you mean about your brain aching...
Mine ached an awful lot to start with.
There are 'handy tricks'(formal or mechanical proofs) to tell whether an argument is invalid or valid. But most people can tell without having to resort to proofs when the arguments are relatively simple (as you did):-)
> (g)
> (P1) Either it is raining or it is wet
> (P2) It is not wet
> ____________________________
> (C) It is rainingIs valid, like you said.
(P1) Tells us that it is either true that it is raining or it is true that it is wet.
(P2) Tells us that it isn't wet.
So... In order for (P1) to be true (which we are asked to assume) It just has to be raining.> (h)
> (P1) If it is snowing then I am cold
> (P2) I am not cold
> ____________________
> (C) It is not snowingThis was a harder one, but it is valid, like you said.
(P1) tells us that if it is true that it is snowing then it just has to be true that it is cold.
(P2) tells us that it isn't cold.
It cannot be true that it is snowing and not cold or this would contradict (P1) So it cannot be snowing.I'll do some more.
Maybe later today or tomorrow...
But once again... No obligation.
:-)
Posted by alexandra_k on May 17, 2005, at 23:24:51
In reply to Re: (((alexandra))) » All Done, posted by gardenergirl on May 17, 2005, at 22:19:56
> And the logic part of the GRE was my best score. And my favorite. They were much more like games than test items. MUCH better than the vocab stuff!
And about a million times better than the math!
I liked doing GRE logic puzzles too.
They have changed it now. No more logic puzzles. Now they give you an argument and ask you to write a commentary on whether it is a good or bad argument.:-(
Not nearly as much fun (IMO):-)
Posted by gardenergirl on May 17, 2005, at 23:28:44
In reply to Re: (((gg))), posted by alexandra_k on May 17, 2005, at 23:24:51
But...that section was not a valid indicator of abilities. There was a definite practice effect that would raise scores of repeaters.
gg
Posted by alexandra_k on May 17, 2005, at 23:50:35
In reply to That's horrible! » alexandra_k, posted by gardenergirl on May 17, 2005, at 23:28:44
> But...that section was not a valid indicator of abilities. There was a definite practice effect that would raise scores of repeaters.
Of course.
Logic is mechanical.
Even a dumb *ss computer can do it.
In fact computers are better at it than people because people tend to want to think outside the box whereas the computer just keeps on cranking away applying the mechanical rules...But the whole GRE is like that.
There are vocab lists to memorise for the verbal section.
Analogies to practice.
There are tricks all the way along.
Thats why they can make a fair bit of money selling study guides and running courses on how to pass it etc etc.And it works.
And I was serious about the cultural bias.
And several questions seemed to be assessing ones attitudes toward american social policy etc etc.'The scales are to justice as the torch is to ___'
'President Bush's recent speech to the Iraq citizens...'
(a) condescending
(b) bold
(c) reassuring...get the general idea???
Posted by Dr. Bob on May 18, 2005, at 0:26:33
In reply to Re: couple more: » alexandra_k, posted by alesta on May 16, 2005, at 23:27:57
> the whole tone of your thread was abrasive... this is a very intelligent (and modest) group that has better things to do than your semester long schoolwork. your post was taunting, pointblank.
Please don't post anything that could lead others to feel accused or jump to conclusions about them. The last time you were blocked it was for 1 week, so this time it's for 3.
If you or others have questions about this or about posting policies in general, or are interested in alternative ways of expressing yourself, please see the FAQ:
http://www.dr-bob.org/babble/faq.html#civil
Follow-ups regarding these issues should be redirected to Psycho-Babble Administration. They, as well as replies to the above post, should of course themselves be civil.
Thanks,
Bob
Posted by Damos on May 18, 2005, at 2:06:36
In reply to Re:Damos, posted by alexandra_k on May 17, 2005, at 23:22:08
Looks simple when you explain it, but all I was creating last night was a mental pretzel ;-)
Relatively simple arguements for a relatively simple person - it was a perfect match then.
Posted by alexandra_k on May 18, 2005, at 5:02:20
In reply to Another victory for luck over good management =0) » alexandra_k, posted by Damos on May 18, 2005, at 2:06:36
> Looks simple when you explain it, but all I was creating last night was a mental pretzel ;-)
Thats ok.
Mental pretzel...
I like that image :-)
Thats the way it was for me.
Until I learned the 'rules' which 'tell' you whether an argument is valid or invalid.
Everyone is capable of follwing the rules.
But being able to tell before you know the rules is much harder.
And you did settle on the correct answers - even though you weren't so sure about them...
Maybe you over-thought it by second guessing your answers and then started with the pretzel thing :-)> Relatively simple arguements for a relatively simple person - it was a perfect match then.
You aren't simple.
You aren't simple at all...
All I mean is that once you know the rules you can figure out whether arguments with 5 or 6 or 9 premises are valid or invalid. But there one needs to follow the rules to figure it out - because there is no way that we can just 'see' it by looking.:-)
Posted by gardenergirl on May 18, 2005, at 10:54:47
In reply to Re: That's horrible! » gardenergirl, posted by alexandra_k on May 17, 2005, at 23:50:35
The Wechsler Adult Intelligence Scales are biased, too, especially on the Information and Comprehension subtests.
sigh
gg
Posted by gardenergirl on May 18, 2005, at 10:59:06
In reply to Re: Another victory for luck over good management =0) » Damos, posted by alexandra_k on May 18, 2005, at 5:02:20
Hmmmm, mental pretzel?
My brain works more like a mental mosaic. And all the pieces seem to "light up" all the surrouding pieces, too. Maybe even a mental "word find" game...all the letters can make lots of words, but I have to find the right word/concept for the moment.
Good for creativity. Makes logic hard. Intuition rules for me. But it makes it really hard to 'splain my thinking to others. Funny, I expect them to take what I say on faith at times, if I can't communicate the parts of the big picture adequately. But me take someone else's statement on blind faith? No way!
The other good part is I can get hours of entertainment following my associations. :D
gg
Posted by alexandra_k on May 18, 2005, at 16:39:14
In reply to More like a mental array or mosaic for me., posted by gardenergirl on May 18, 2005, at 10:59:06
> My brain works more like a mental mosaic. And all the pieces seem to "light up" all the surrouding pieces, too. Maybe even a mental "word find" game...all the letters can make lots of words, but I have to find the right word/concept for the moment.
Sounds like a neural network to me...
The 'lighting up' are the exitatory connections... 'Sparrow' makes you think 'bird' 'flies' 'feathers' etc etc...
> Good for creativity. Makes logic hard. Intuition rules for me. But it makes it really hard to 'splain my thinking to others. Funny, I expect them to take what I say on faith at times, if I can't communicate the parts of the big picture adequately. But me take someone else's statement on blind faith? No way!
> The other good part is I can get hours of entertainment following my associations. :D:-)
The other side to that is inhibitory connections.
So when you think something like P is true then you are supposed to be able to inhibit P is false for the rest of the puzzle..I think I get what you mean, though.
Logic comes hard for people.
We are a connectionist system on the neural level(a neural net).
(That is opposed to how a computer works where it just follows rules)
We can follow rules, but they come harder...
Posted by Larry Hoover on May 19, 2005, at 8:48:55
In reply to Re: (((alexandra))), posted by All Done on May 17, 2005, at 1:11:09
I don't know what went wrong with my computer last night, but it crashed my IE twice when I was trying to answer this thread. Might be karma. Or it might not. ;-)
> I've read logic puzzle books just for fun. I wonder if Larry has, too.
Many years ago, perhaps, but I find them tiring now. I have to limit my cognitive "expenses", as they are on a budget. Just like you manage money.
What draws me to this sort of issue really arises from formal debate of ideas. Recognizing the various fallacies, arguments of distraction, and so on. They are nearly all ancient recognitions of faulty thought: petitio principii (begging the question....you must believe the assumption(s) in order to accept the conclusion); argumentum ad vericundiam (appealing to a higher authority for the "truth", or expert opinion); argumentum ad hominem (numerous variants, all meant to distract the argument to the attributes of the presenter, rather than the issue at hand e.g. argumentum ad hominem circumstantis, trivializing an economic argument posed by a person who is unemployed); and of course, the direct fallacies known as denying the antecedent and affirming the consequent. Those are the formal names of what we've been doing here, determining the validity of propositional arguments. Some propositional arguments are so absurd, they have a special label: non sequitur, Latin for "it does not follow". In those cases, the conclusion is logically unrelated to the proposition.
Lots more at:
http://www.fallacyfiles.org/index.htmlMore examples, and nicely explained, at:
http://www.infidels.org/news/atheism/logic.htmlKnowing how to both discover these arguments, and to present them without yourself falling into using them, is a real art. I really like the challenge in doing so.
The difficulty in employing such arguments is that some people take *all* argument as being ad hominem (directed at the person), even if it is absolutely clear that the argument is about an idea. Anyway.....
> Even if I can't figure them out all the time (or maybe even most), I love the process of thinking it through and trying to figure out the right answer. I can get lost in my thoughts that way. It's a nice escape.
>
> And when I know there's a right answer and I've figured it out...woohoo! Yeah, I'm a geek.
>
> :)Yes, then you are indeed a geek.
:-)
Lar
Geek
Posted by alexandra_k on May 19, 2005, at 18:46:00
In reply to Re: (((alexandra))) » All Done, posted by Larry Hoover on May 19, 2005, at 8:48:55
There are two sides to this:
Critical reasoning / thinking
Logic
They are related... But a bit different.
Critical reasoning / thinking deals with arguments in a natural language (English or whatever) and looks at evaluating whether they are good arguments or not. Part of that process of evaluation is the formal question of validity, but then there are also a lot of other things that can go wrong (lots of 'substantive fallacies' in which the premises are false) and lots of verbal tricks to make something appear valid whereas really it is not.Logic looks solely at argument structures or forms. Typically by translating English (or whatever natural language) into a logical (artificial) language such as the higher or lower predicate calculus first.
It doesn't care whether the premises are in fact true or not because it considers every possible arrangement of truth values. Any argument that has an invalid structure is an example of a formal fallacy - and there are two ones that occurr commonly enough to be given names:
The fallacy of denying the antecedent and the fallacy of affirming the consequent.From the extract:
>Many times in the past, people have concluded that because something is logically impossible (given the science of the day), it must be impossible, period.
But that doesn't follow...
Logical possibility and impossibility is an objective matter. Basically, something is logically impossible if it describes a contradictory state of affairs. e.g.
It is raining and it is not raining.
That sentance describes a logically impossible state of affairs - so long as 'raining' means the same thing both times it occurs.
Science doesn't show us anything at all about the notion of logical possibility / impossibility / necessity.If we plug the laws of nature (of the best scientific theory we have) in as premisses and assume that they are true and see what we can and cannot deduce from them then we have what is and is not physically, or metaphysically, or naturally, or nomologically necessary / possible / impossible etc.
So IF we assume the best scientific theory of the day THEN we can deduce what must be the case in the world (according to the theory).
If the conclusion turns out to be false of the actual world then it means that one of the premises (ie some of the laws of nature that appear in the scientific theory) must be false.So... Perpeptual motion machines are logically possible. This is because there is no contradiction in the idea. If the present scientific theory is correct, however, then perpeptual motion machines are naturally or metaphysically or nomologically or physically impossible. Because the existence of perpeptual motion machines would contradict the theory.
If we found a perpeptual motion machine then that wouldn't be a problem for logic. It would be a problem for the scientific theory. We would have to revise the premises (ie the scientific theory).
>It was also believed at one time that Euclidean geometry was a universal law; it is, after all, logically consistent. Again, we now know that the rules of Euclidean geometry are not universal.
There is another theory. Same scenario. Logical consistency comes too cheap. It is easy to find. Just because something is logically consistent doesn't make it a universal law...
>Secondly, logic is not a set of rules which govern human behavior. Humans may have logically conflicting goals. For example:
John wishes to speak to whoever is in charge.
The person in charge is Steve.
Therefore John wishes to speak to Steve.
Unfortunately, John may have a conflicting goal of avoiding Steve, meaning that the reasoned answer may be inapplicable to real life.Sure we have different goals. It is an axiom of 'folk psychology' that:
People will act in such a way as to satisfy their desires were their beliefs true (this is a rationality constraint).
It is acknowledged that people have different desires (goals).
The notion is that people act from the 'strongest' goal.So:
What is the rational thing for John to do???
John has two desires.
1. The desire to speak to the person in charge.
2. The desire to not speak to Steve.If John desires more to speak with the person in charge then it is rational for him to talk to Steve.
If John desires more to not speak with Steve then it is rational for him to not speak with Steve.Logic cannot tell us what he most desires (ie what IS the case).
But it can tell us what it is rational to do GIVEN different desires.That isn't a problem for logic either...
This is the end of the thread.
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