The extended mind thesis basically states that we're in error if we think that our mind "ends" at the boundary of our skull. The original formulation (by Andy Clark and David Chalmers) offers a thought experiment as intuitive evidence for this claim. Suppose, they say, that there is a man named Otto who is afflicted with mild Alzheimer's disease. Otto knows that he has significant memory problems, and so carries with him a notebook and pencil at all times. When he learns some new piece of significant information (e.g. the address of a restaurant he wants to visit), he writes that information in his notebook. He keeps the notebook very well organized so that when he wants to find some piece of stored information, he can flip right to it. Now, argue Clark and Chalmers, is it not fair to say that Otto's notebook plays the same role to him that a "normal" person's biologically based memory does? Just as I can be said to believe "Blondie's Pizza is at the corner of Telegraph Avenue and Channing Street" even when I'm not actively thinking about the location of Blondie's Pizza, Otto can be said to really believe the same thing when it is written down in his notebook.
Put this way, the extended mind thesis seems obviously false to me. The only reason Otto needs his notebook in the first place is because there is something wrong with his memory. To reiterate: the notebook, while perhaps fulfilling a functional role similar to that of normal biological memory is only necessary precisely because his memory has failed him. The notebook is nothing more (or less) than an external tool to help him live with a disability, but it is no more memory than a cane is a third leg.
However, Mr. Josephy raises an example that seems a little less cut and dry. Snip from his post:
The idea is that as technology evolves so does our cognition and our ability to process information efficiently. It probably isn’t going to that long till we all have decent internet on our phones, thus when you’re in the middle of town and you want to know someone you can just get your mobile out, open Google, search and there you go. The interesting question follows: Does the internet (which you now always have near immediate access to) count as part of your mind or at least your knowledge base. Most of course would answer no, just as they wouldn’t count a bit of paper with a number on it as part of your mind.
However yet further into the future there’s a good chance that people will be able to get chips in their brain that wires them up to the internet so they have immediate access at any time. It sounds like the stuff of science fiction, but I don’t think it can be ruled out. It’s certainly possible in principle and as technology evolves so will society’s values. Even if it never happens, the thought experiment is still there. Does the knowledge on the internet count as yours; does your mind extend into it? It’s hard to argue no unless you say the mind is only linked to the biological brain or you believe in a soul. Such a situation would mean you had the same instant access to information on the internet as you did with your biological brain. Such an invention, to coin a Jungian term, might well lead to an “unconscious collective”, or in fact better phrased; a “Conscious Collective”. Of course it may turn out that this never happens or that its impossible, but it does raise a very interesting point on the boundaries of the mind.
This does indeed raise a very interesting point, and it's one that I'm more hesitant about dismissing outright. Still, though, my intuition is that even with such a chip, the contents of the internet would not count as contents of my mind. Let's extend the Otto analogy a bit. Suppose that in addition to having Alzheimer's, Otto also has the misfortune of having lost his eyesight in an industrial accident. Now, suppose that with the advent of future technology there is a way for us to overcome Otto's blindness by way of surgically implanting artificial eyes in his skull. Suppose Otto has this operation and, upon its completion, the doctors hand Otto a notebook, telling him "With these eyes, your memory problems are over! We've given you the means to directly access a vast source of information and have it transmitted directly into your mind. All you have to do is point your fancy new ocular implants at this notebook, and anything you've recorded in it will be immediately apprehensible to you."
I've already made a case for why it would be unsatisfactory to make such a claim as this, but given this formulation the analogy with the wifi chip seems strong--by implanting such a chip, science will have given me the ability to (roughly) perceive in a new modality, and to access new information with that modality. However, just as giving someone a notebook and the physical capability to make use of it does not count as extending his mind, giving someone a wifi chip and access to Google doesn't seem to count either.