Re: [SystemSafety] EASA Notice of Proposed Amendment 2014-13

From: Matthew Squair < >
Date: Tue, 22 Jul 2014 12:45:04 +1000

Nor a reference to James Armstrong's contemporaneous work on deconstructing safety arguments via adversarial counter argument (publ. 2004).

Matthew Squair

MIEAust, CPEng
Mob: +61 488770655
Email; Mattsquair_at_xxxxxx

On 22 Jul 2014, at 1:03 am, Peter Bernard Ladkin < ladkin_at_xxxxxx

Because EASA talks about safety/assurance cases, cites Toulmin and then uses its own conception, I
thought I'd look up the international standard on assurance cases, ISO/IEC 15026 Part 2.

It's 10pp long, including 2pp of Bibliography. The Bibliography includes a lot of ISO and IEC
standards, a bunch of "Ministry of Defence" standards, without indicating which they might mean
(answer: the UK), a couple of references to Altran UK's SafeSec project, including only URLs which
no longer work (hint to the wise: grandfather your URLs when you revamp your WWW site! Back twenty
years ago when we first taught people about WWW design this was de rigeur), a reference to
Greenwell, Knight and Pease's taxonomy of fallacies (in ISSC 2006), and to Tim Kelly's diss.

Nothing to Toulmin, Parsons, or anyone in the argumentation community.

It's not bad, though. I'm somewhat unsure as to what a "justification" is; it seems to sit in
between a claim and an assumption. It is said to be "a reason for the choice of a claim": isn't
there always just one valid such reason, namely that the claim is required to validate the argument?

The "blurb" is almost two pages long, leaving about five and a half pages for substance. It does
better than EASA NPA 2014-13. Assurance cases consist of claims, arguments, evidence, justifications
and assumptions (whereas NPA 2014-13 leaves the last two out) and it sort-of specifies the relations
between them.

Since it is an international standard on something the EASA NPA 2014-13 requires, namely assurance
cases, one wonders why it was not cited.

Does anyone know who was on the committee which wrote 15026-2?

PBL Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Tel+msg +49 (0)521 880 7319

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