Re: [SystemSafety] A Whimsical Paradox

From: Michael Jackson < >
Date: Thu, 29 Jan 2015 16:33:27 +0000


Your logical paradox paper is fun. Thank you.

I think we must distinguish two classes of case in which everyday reasoning does not 'adhere to classical logic'. One is the case of a person who says "Eight times seven equals fifty four". The other is the case of the person who says "Everybody loves my baby but my baby loves only me."

The first person intends to make a true assertion about arithmetic, but by ignorance or carelessness, or incompetence at calculation, instead asserts a falsehood. The second person makes a statement apparently implying "I am my baby" (work it out!), but intends no such implication and, of course, does not believe it and would certainly deny it.

The second case merely reflects the looseness of everyday language. Even a seemingly precise statement ("Everybody loves my baby") may use a term ('everybody') informally and loosely: the speaker means, and the hearer will understand, that in this assertion 'everybody' does not include 'my baby'.

When we include terms denoting phenomena of the real world we must rely on very loose interpretations. Perhaps "P1 loves P2" must be understood to be irreflexive: P1 /= P2 is implied because for P1 = P2 we would introduce the word 'self' somewhere. Similarly, with suitable interpretations, the matter
of 'confidentiality' need involve no logical inconsistency.

However hard we try to tighten our interpretations there is always room for further doubts. The interesting question is: How can we ever model the real world phenomena adequately for dependable system development? The key, I think, is to recognise that a model, with its interpretations and universally
quantified assertions, can be good enough in a particular restricted region of the system's operating envelope. This ought to be (actually is?) an explicit consideration in designing the structure of the system behaviour. Many realworld  models are needed for adequacy in the current region of the operating envelope.

At 05:46 29/01/2015, Peter Bernard Ladkin wrote:
>I'd not really heard about the "Chem Trails" nonsense except
>superficially, had an odd encounter on
>a bus, and asked people about it on a closed mailing list I am on.
>Mike Holloway said, well,
>everyone believes *some* nonsense.
>I am interested in everyday reasoning, which, contrary to what many
>people believe, regularly and
>justifiably does not always adhere to "classical" logic. I would say
>that an example is Mike's
>claim. I saw the chance to construct a classical-logical paradox.
>Maybe I did; maybe I didn't.
>The paper is aimed at curious teenagers rather than those with any
>technical training. But at least
>one adult has claimed to find it interesting. Perhaps others here might?
>Prof. Peter Bernard Ladkin, Faculty of Technology, University of
>Bielefeld, 33594 Bielefeld, Germany
>Je suis Charlie
>Tel+msg +49 (0)521 880 7319
>The System Safety Mailing List

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systemsafety_at_xxxxxx Received on Thu Jan 29 2015 - 17:33:28 CET

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