Not even Andy Clark believes the internet counts as an extension of the mind. Implanting a chip into your head doesn't change the epistemological relations one has to the information in one's environment.
Clark and Chalmers give explicit criteria that specify when an external resource counts as an extension of the mind. They call it the parity principle:
"If, as we confront some task, a part of the world functions as a process which, were it to go on in the head, we would have no hesitation in accepting as part of the cognitive process, then that part of the world is (for that time) part of the cognitive process."
In other words, not everything that is functionally identical to mindware counts as a mind extension. It has to be primed for use in just the right way. Otto's notebook counts as memory not just because it store information functionally similar to his biological memory. In fact, the notebook isn't really functionally identical to his biological memory at all. But it counts as a mind extension because Otto automatically consults in in normal circumstances, and immediately accepts the information stored there, and these epistemological and phenomenological relationships are identical to Inga's use of her biological memory.
So yeah, if someone gets Alzheimer's disease, it is little consolation to hand them a notebook and say "you'll be fine". That's because the person isn't used to using a notebook as an extension of their mind.
But consider the opposite case, for instance when you lose your cell phone, or your computer breaks, and how helpless you feel without it. That feeling is roughly analogous to situations when people lose their memory, or a limb, because they understand their world in terms of having those resources constantly available for use.
In other words, I think your objections (and the objections on the other blog) completely miss the point of the extended mind.
Seriously. Read some Clark. Being There and Mindware are extremely compelling.
First of all, that definition seems way too loose for my taste; it smacks of the SCOTUS definition of pornography ("I can't define it but I'll know it when I see it"). A definition along the lines of the one Eripsa attributes (correctly, I assume) to Clark seems to weaken the thesis as it is intended to be--it seems to admit an important tie between cognitive processes and the fact that those processes are going on "in the head."
My point here is that if we're going to argue about this, I feel like we need a more rigorous definition as to what precisely we mean by a "cognitive process;" if extended mind proponents are going to win the day, it also seems like that definition can't have anything to do with such processes being in the head.
Now on to the other points. So if I'm understanding you correctly, what counts as part of my mind depends on what I think counts as part of my mind? Once again, the point seems either flat out wrong or trivially true, depending on how you look at it--sure, I understand the world in terms of having my cell phone available for my use, but is that really all it takes to make it part of my mind? I understand my world in terms of the fact that I'm wearing pants, too, and I'd probably feel just as naked (ha ha) if my pants disappeared as if my phone did, but are pants part of my mind? You'll probably object that my pants play no role in "cognitive processes," but again I'd ask for a tight definition as to just what that means--I could probably make a case for my "cognitive processes" being impeded by the knowledge that everyone is staring at my naked ass, and thus for pants playing a vital role in those processes.
As to Otto's notebook, I'm not sure what you mean when you say that it is "phenomenologically identical" to Inga's memory; it seems to me that no two things could be more phenomenologically disparate than consulting external documentation and internal memory.
I'll admit that I don't know as much about this topic as Eripsa does, so his charge that I'm missing the point with my objections might be accurate (but I doubt it). I'll pick up those books he recommended, and would urge readers to do the same.