[SystemSafety] Engineering depends on making arguments (was Re: Fwd: Measurement + Control)

[Nancy Leveson]

Michael,

I think you are really stretching the definition of "argument." We don't
document, design, analyze, etc, just for the purpose of "argument." We
document, for example, in order to aid communication and to allow
maintenance and change to designs.

There are many ways of verifying things beyond logical argument as the term
is used on this list.

Nancy


On Mon, Dec 16, 2013 at 6:25 AM, C. Michael Holloway
<c.m.holloway at nasa.gov>wrote:

>  > Engineering is not about making "arguments."
>
> At one level, the statement is trivially true.  Engineering is (by
> definition) about constructing practical products.  The desired end result
> is, for example, a bridge, not the designs and analyses of the bridge.
>
> But at another level, the statement is false.  Producing the desired end
> product necessarily requires specification, design, analysis, and
> associated activities.  These activities in turn necessarily produce
> results, which are usually embodied in documents.  These documents
> necessarily contain many arguments.  Some of these arguments may be
> explicit (for example, calculations about the load that a particular truss
> must support).  Some of these arguments may be implicit (for example, the
> implicit argument underlying a decision to adopt a particular design as
> sufficiently safe based on the results of a thorough hazard analysis).
> Whether implicit or explicit, arguments permeate every aspect of
> engineering.
>
> Arguments are not the end product of engineering, as they are of
> philosophy.  But without arguments, there is no engineering.
>
> --
>
> C. Michael Holloway
>
> Disclaimer: My opinions are mine alone. Give neither blame nor credit to
> my employer for them.
>
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>


-- 
Prof. Nancy Leveson
Aeronautics and Astronautics and Engineering Systems
MIT, Room 33-334
77 Massachusetts Ave.
Cambridge, MA 02142

Telephone: 617-258-0505
Email: leveson at mit.edu
URL: http://sunnyday.mit.edu
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