As always, thanks, Bruno for taking the time to educate this bum.
Starting at the bottom:
"To ask a logician the meaning of the signs, (...) is like asking
the logician what is logic, and no two logicians can agree on the
possible answer to that question."
*This is why I asked  --  YOUR  -- version.*
***
"Logic is also hard to explain to the layman,..."
*I had a didactically gifted boss (1951) who said 'if you understand
something to a sufficient depth, you can explain it to any avarage educated
person'. *
*And here comes my *
*"counter-example" to your A&B parable: condition: I have $100 in my purse.*
*'A' ** means "I take out $55 from my purse" and it is true. *
*'B' means: I take out $65 from my purse - and this is also true. *
*A&B is untrue (unless we forget about the meaning of & or and . In any
language.*
***
*"*I think you are pointing the finger on the real difficulty of logic for
beginners...."
*How else do I begin than a beginner? to learn signs without meaning, then
later on develop the rules to make a meaning? My innate common sense refuses
to learn anything without meaning. Rules, or not rules. I am just that kind
of a revolutionist. *
*Finally, (to begin with) *
*..."*study of the laws of thought, although I would add probability theory
to it ...???"
*I discard probability as a count - consideration  inside a limited (cut)
model, 'count'*
*- also callable: statistics, strictly limited to the given model-content of
the counting - *
*with a notion (developed in same model) "what, or how many the next simialr
items MAY be" - for which there is no anticipation in the stated
circumstances. To anticipate a probability one needs a lot of additional
knowledge (and its critique) and it is still applicable only within the said
limited model-content. *
*Change the boundaries of the model, the content, the statistics and
probability will change as well. Even the causality circumstances (so
elusive in my views).  *
**
*Regards*
*John*

**
**


On Tue, May 19, 2009 at 11:51 AM, Bruno Marchal <marc...@ulb.ac.be> wrote:

>
> Hi John,
>
>
> On 18 May 2009, at 21:00, John Mikes wrote:
>
> > Bruno:
> >
> > could you tell in one sentence YOUR identification for logic?
>
> That is a difficult question, and to be honest, I am still searching.
> As a platonist (that is: classical logician) I am OK with the idea
> that logic is the abstract (domain independent) study of the laws of
> thought, although I would add probability theory to it (like Boole).
>
>
>
> > (I can read the dictionaries, Wiki, etc.)
> > I always say :common sense, but what I am referring to is
> >    -- --  M Y -- -- common sense,
> > distorted - OK, interpreted - according to my genetic built, my
> > experience (sum of memories), instinctive/emotional traits and all
> > the rest ab out what we have no idea  today yet.
>
> I can agree with this, althought the aim is too suppress as far as
> possible the distortion.
>
>
> >
> > I never studied 'formal' logic, because I wanted to start on my own
> > (online mostly) and ALL started using signs not even reproducible on
> > keyboards
>
> That is why Knuth invented LATEX :)
>
>
>
> > and not explained what they are standing for. As I guessed: the
> > 'professors' issued "notes" at the beginning of the college-courses
> > (($$s?)) and THERE the students could learn the 'vocabulary' of
> > those signs.
> > You also use some of them.
>
> I think you are pointing the finger on the real difficulty of logic
> for beginners. You are supposed not to attribute meaning on those
> signs, because what the logician is searching for is rule of reasoning
> which does not depend on the meaning. The hardness of logic is in the
> understanding of what you have to NOT understand to proceed. Logicians
> take the signs as just that: sign, without meaning. Then they will
> develop rule of transformation of those sign, in such a way that
> machine can play with them, and mathematical rule of meaning, and they
> are happy when they succeed to find nice correspondence between rule
> and meaning. It makes the subject both very concrete and abstract at
> the same time. I am used to think that logic is the most difficult
> branch of math. Somehow, computer science makes it more easy. It
> motivates the point of not trying to put meaning where none is
> supposed to be.
>
>
>
>
> >
> > I was looking at a dozen books as well and did not find those signes
> > explained, not in footnotes, not in appendicis, not as intro- or
> > post- chapters. They were just applied from page 1.
> > So I gave up.
>
> I can understand. It is hard to study logic alone. Yet there are good
> books, but it takes some effort to understand where you have to take
> those sign literally. I would suggest the reading of the little
> penguin book by Hodges "Logic", which is perhaps clear for an
> introduction.
> Logic is laso hard to explain to the layman, because it concerns
> objects which look like formal things, and it takes time to understand
> that we study those objects without interpreting them. beginners take
> time to understand the use of saying that, for example, we will say
> that "A & B" is true when A is true and B is true. They can believe
> that they learn nothing here, but they are false because the "&" is
> formal, and the "and" is informal. After all you do learn something if
> I say that "A et B" is true when A is true and B is true. In this case
> you learn french, which are at the same level of informality, but in
> logic you attach rules and meaning to explicitly formal things on
> which you reason *about*.
> To ask a logician the meaning of the signs, is a bit like asking a
> biologist the meaning of "ATTAGTTCAATCCCT" or DNA. It is like asking
> the logician what is logic, and no two logicians can agree on the
> possible answer to that question.  When student ask some question
> here, it is not rare the answer he get is just "we are not doing
> philosophy here". The object study is far more concrete than beginners
> can imagine, and that is why the notion of machine and computer
> science can help a lot for many parts of logic.
>
> Bruno
>
>
> http://iridia.ulb.ac.be/~marchal/
>
>
>
>
>
>

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