After reading the last few posts, all of which I have enjoyed, I am writing
this. It is, hopefully, an accurate, summary of Vincenti's position.

First, to the comment about Polanyi from Chris, there is no question that
Vincenti drew from Polyani. But I would not be in a position to say whether or
not he is "guilty of a rather limited interpretation." He seems to draw more
heavily upon Edwin Layton, Edward Constant, Donald Campbell, Rachel Laudan,
and John Staudenmaier. As for citations, John Feland posted the link to the
complete written works of Vincenti
(http://www.stanford.edu/group/STS/wgvworks.shtml).

R. Allen Reese said:

>may I comment that flapping is a mechanism for
>producing thrust, not lift.  A bird gets lift because its wings have the
>aerofoil section, and flapping is used to rotate the outer feathers
>(primaries) as propulsion.  Hence birds using alternative energy sources
>(thermals, cliff updrafts, wind/wave interactions) do not need to flap.
>The engineering problems that kept Man out of the air were more to do with
>the weight/strength ratio of available materials and power sources

I would agree that "materials" played a significant role in keeping man out of
the air. However, I would argue that the misunderstanding of what relevant
feature of flight to abstract out of observations of birds and apply to man's
situation was a bigger part of the problem.

Orville Wright is quoted as saying, “Learning the secret of flight from a bird
was a good deal like learning the secret of magic from a magician. After you
know the trick and what to look for, you can see things you didn’t notice when
you did not know exactly what to look for” (Combs, 1979).

The misunderstanding that the critical principle was flapping led people off
in unfruitful directions. Until the focus changed to rigid wings did we begin
to progress. But, and this is where we get to Vincenti, the relevant issue at
hand is what did those engineering a solution really settle on? Was it a rigid
wing or was it the underlying principle of how the rigid wing brings forces
together to produce the desired effect of lift?

Vincenti's purpose seems to be to on the "intellectual content of
engineering." Hence the title of his book, "What Engineers Know and How They
Know It." He defines six categories of knowledge. He admits they they are not
exhaustive and there is some overlap between categories. But it is a framework
for beginning to quantify and qualify what engineering knowledge is about. His
categories are:

1. Fundamental design concepts
2. Criteria and specifications
3. Theoretical tools
4. Quantitative data
5. Practical considerations
6. Design instrumentalities

The part I am particularly interested in is his "Fundamental design concepts."
Here is where he defines the "operational principle" and the "normal
configuration." (He draws the term operational principle from Polanyi's work
and in this regard appears to define it as Polanyi does.) It is this
operational principle that is the mechanism by which things happen. The
operational principle for flight being that of lift. However, there is an
operational principle in thrust as well as the components within the device.
Each device resolves forces to accomplish some end.

Each artifact has one or more operational principles involved. But the way the
operational principle gives rise to the physical structure of the artifact is
what is called the normal configuration. Given the operational principle that
explains lift we can define a variety of normal configurations including fixed
wing aircraft and rotary wing aircraft. Each uses the same operational
principle for lift but in a different normal configurattion.

This is where we get to the question of "generative" principles or ideas and I
will end this post since it seems to get into other issues.

Jon