Re: the official definition [of web accessibility] from the W3C is wrong

Kate said: "For a conversation about accessibility to affect change, you 
have to position it as a tool to achieve the goals that your audience 
already has."

OK, I really think I agree with that statement, especially from the 
perspective of inclusive design and inclusive user experience.  I 
regularly use the concepts of disability and accessibility when 
identifying the "hills" (Note 1: a design thinking term) for the web app 
being designed.

When Kate says: " Our definition: "Disability is the deficit between user 
and system capability.  Is it the responsibility of the system, not the 
user, to bridge that deficit."
is fine until you better define the term "system".  One of the issues I 
discussed was where the "system' that everyone else had was able to bridge 
the deficit for them.  And so then you quickly get to the point of which 
part of the system needs to finishing bridging the deficit. 

For example, if the 'system' doesn't have voice command and control as an 
alternative to keyboard or mouse command and control, then it doesn't 
bridge the deficit needed by many individuals.  If the response is, oh, 
just get an additional piece of assistive technology, I'm OK with that 
too, as long as that assistive technology is capable of inter-operating 
with the rest of the system and the rest of the system has a way (APIs, 
keyboard commands to map the voice commands to, etc.) of inter-operating 
with the assistive technology.  My early ViaVoice example was where it 
wasn't initially capable if being used by a person who couldn't use a 
mouse - the ViaVoice plus the 'rest of the system' didn't bridge the 
deficit because of an early problem in ViaVoice itself, not with the rest 
of the system.  The system was accessible to a lot of other users, and 
accessible to a lot of other users who had other assistive technologies 
combined with it, but for those users who not only wanted to use voice 
command & control, but for which it was essential that it fully 
inter-operate with the rest of the system, the 'system' wasn't fully 
accessible to them. 

So, for your definition of 'disability' (the gap) to be effective in 
causing change, or my definition of 'accessibility' (gap is bridged), the 
definition has to include the definition of the 'users' - and - 'system', 
all the parts of the system that have responsibilities.  I believe what 
the community, especially the accessibility community has been doing for 
the last 33 years since the advent of the Personal Computer in 1981, is 
devising adaptive devices, creating assistive technologies (AT), and 
adding capabilities into the 'system'. 

Often it is not effective to tell web sites owners or web app designers 
that they are responsible for the "whole system" or "bridging the whole 
deficit".  There is an implied essential partnership between the 
components in the system - between the AT, the browser, the platform 
(operating systems such as Windows, iOS, Android, etc.).  If the Web app 
meets the success criteria of WCAG, and the browser meets the success 
criteria is UAAG, then we can say that at least those two components have 
met their responsibility.  There still may be a deficit between some users 
and the system, but at least we know where to focus our efforts to bridge 
the rest of that deficit. 

When defining the 'user' we also have to think of the user's education, 
training, and awareness.  Often the user will experience a problem - a 
disability - a deficit between the user and the system, but the problem or 
fix is actually on the user's side.  For example, if the fonts appear too 
small, and the web site owner has made it compatible with zoom, and the 
browser provides zoom, but the user doesn't know to use zoom (or forgot to 
zoom), then it is the user that needs to do his or her part.  Sure we 
could also expand the definition of 'system' to include the social 
responsibilities - for example we could say that the 'system' failed the 
person because the 'system component' that is responsible for providing 
the education, training, and awareness (e.g. advocacy groups) failed. Or 
perhaps some other responsible party in the ecosystem.  But I prefer to 
simplify it for web site owners and instruct them on their 
responsibilities, and make them aware of the other possible deficits in 
other system components that they may choose to compensate for.  A real 
life example from the late 1990's - when explaining 'disability' to a 
bunch of "new web masters", I was asked: "does that mean I need to produce 
a radio version (audio broadcast) of my web site?  I replied, No!, the 
vision impaired person gets and uses a screen reader, which reads the text 
(via TTS or Refreshable Braille), you Mr Web Master just have to make it 
compatible with the screen reader.  To which I was then asked, "Well, who 
provides them the screen reader?  Which ones do I need to test?, 

Are earbuds and personal eye glasses part of the user or part of the 
system?  the answer matters because your definition said that "Is it the 
responsibility of the system, not the user, to bridge that deficit."

Also, why redefine the term 'disability'? Why not just use the phrase: "
deficit between user and system capability" as the thing to focus on? 
Disability is defined in lost of places (Wikipedia, WHO, etc.) and could 
cause confusion with our goal of bridging the gap, eliminating the 
deficits, etc. etc.  In other words I agree with your intent of affecting 
change. 

My challenge over the past almost 2 decades has been where best to focus 
my energies to most efficiently affect improvement (not just change). That 
is my challenge to all of us in this community.  Quoting Dallin H, Oaks, 
whom I have come to respect  - "We have to forego some good things in 
order to choose others that are better or best".

I also recommend that our definition of 'accessibility' (or 'disability') 
needs to have both a visual graphic and a text description to be able to 
'fully communicate' the definition of the concepts and components we are 
trying to use to inspire ourselves and others to take action. 

For a nice visual graphic and text description of the essential components 
of the concept of "web accessibility" - see 
http://www.w3.org/WAI/intro/components.php
____________________________________________
Regards,
Phill Jenkins, 
IBM Accessibility
http://www.ibm.com/able
http://www.facebook.com/IBMAccessibility
http://twitter.com/IBMAccess
http://www.linkedin.com/in/philljenkins

Note 1: Hills - in IBM Design Thinking, Hills are clear statements that 
frame project's releases on user outcomes. Rather than cataloging a list 
of features, functions and capabilities for a project, designers, 
engineers, and project managers work together to define what users should 
be able to do when working with the product.