Andy Clark and David Chalmers (1998) present the following famous case.
Otto suffers from Alzheimer's disease, and like many Alzheimer's patients, he relies on information in the environment to help structure his life. Otto carries a notebook around with him everywhere he goes. When he learns new information, he writes it down. When he needs some old information, he looks it up. […] Today, Otto hears about the exhibition at the Museum of Modern Art, and decides to go see it. He consults the notebook, which says that the museum is on 53rd Street, so he walks to 53rd Street and goes into the museum.
Clark and Chalmers (hereafter C & C) argue that 'Otto believed the museum was on 53rd Street even before consulting his notebook' (Clark and Chalmers 1998: 13). The belief is not physically realized inside his head. It is rather physically realized in his notebook. In other words, the belief 'extends into the world'.
[The TEDx talk 'Is your phone part of your mind?' by Chalmers is a nice introduction to the topic.]
Their claim seems to be a radical one. As Robert D. Rupert points out, the idea of extended mind "would alter our approach to research and theorizing in cognitive science and, it would seem, significantly change our conception of persons" (Rupert 2004: 389–90). In addition, the idea of extended mind would have important implications to a variety of issues in epistemology (Pritchard 2010, Carter et al. 2014), neuroethics (Levy 2007a, 2007b), etc.
The claim by C & C is:
Otto’s Extended Belief (OEB): Otto’s belief that the museum is on 53rd Street is physically realized in his notebook.
Which is the conjunction of two claims:
OEB1: The belief that the museum is on 53rd Street is physically realized in the notebook.
OEB2: It is Otto who believes that the museum is on 53rd Street.
How do C & C defend OEB?
The main argument for OEB is a functionalist one. OEB is true because, first, in the following case of Inga, Inga’s belief that the museum is on 53rd Street is physically realized in her internal memory storage and, second, there is no relevant functional difference between the role of the notebook for Otto and the role of the internal memory storage for Inga; 'the notebook plays for Otto the same role that memory plays for Inga' (Clark and Chalmers 1998: 13).
Inga hears from a friend that there is an exhibition at the Museum of Modern Art, and decides to go see it. She thinks for a moment and recalls that the museum is on 53rd Street, so she walks to 53rd Street and goes into the museum.
The argument has invited a variety of responses. The focus of the debate in the extended mind literature has been on OEB1. Critics are not convinced that the functionalist argument establishes that a belief is physically realized in the notebook. For example, Adams and Aizawa (2001) and Rupert (2004) argue that there are in fact relevant functional differences between the notebook for Otto and the internal memory storage for Inga. My focus in this paper, on the other hand, is on OEB2, which tends to be neglected in the literature.
This paper presents a new objection to the functionalist argument for OEB. I call it 'the systems reply' to the functionalist argument because it is analogous to the systems reply to Searle's (1980) Chinese room argument. Searle argues that what he calls 'strong AI (Artificial Intelligence)', a version of functionalism, leads to the absurd consequence that a person (call him 'John'), with no experience of learning Chinese, understands Chinese by entering a room and manipulating symbols in accordance with the instructions in the book in the room. According to the systems reply to the Chinese room argument, what actually follows from strong AI is not that the person in the room understands Chinese but rather that the hybrid system, consisting of John and things in the room (such as the instruction book) understands Chinese. Similarly, according to the systems reply to the functionalist argument for OEB, what actually follows from the argument is not OEB but the following claim:
Otto-Notebook System’s Belief (ONSB): The Otto-notebook system’s belief that the museum is on 53rd Street is physically realized in the notebook.
Which is the conjunction of two claims:
ONSB1: The belief that the museum is on 53rd Street is physically realized in the notebook.
ONSB2: It is the Otto-notebook system, rather than Otto, that believes that the museum is on 53rd Street.
ONSB1 is identical with OEB1. Thus, the difference between OEB and ONSB consists in the difference between OEB2 (which attributes the belief to Otto) and ONSB2 (which attributes the belief to the Otto-notebook system).
It should be noted that C & C expected this type of responses. Indeed, it is part of their own claim that in cases such as Otto’s case, 'human organism is linked with an external entity in a two-way interaction, creating a coupled system that can be seen as a cognitive system in its own right' (Clark and Chalmers 1998: 8). C & C, however, are not fully aware of the tension within their own commitments. One the one hand, they defend OEB according to which it is Otto who believes that the museum is on 53rd Street. On the one hand, however, they argue that a hybrid system consisting of Otto and his notebook has been created.
The paper also discusses Sprevak's (2009) challenge to functionalism. C & C defends the extended mind thesis on the grounds that it is entailed by functionalism. Sprevak accepts that functionalism entails the extended mind thesis but, unlike C & C, he thinks that this is actually a problem of functionalism.
According to Sprevak, functionalism entails not just OEB but also radical and absurd instances of extended beliefs. For instance, it entails that someone (call him 'Mark') comes to believe that Alpha Centauri A is bigger than the sun just by picking up a book from the shelf that happens to contain the sentence 'Alpha Centauri A is bigger than the sun'. These consequences are unacceptable. This means, according to Sprevak, that there is something wrong with functionalism.
The systems reply provides a nice response to Sprevak's challenge. Indeed, his argument is based upon the same mistake made by Searle and Clark and Chalmers. Functionalism does not entail that Mark believes that Alpha Centauri A is bigger than the sun just by picking up the book from the shelf. Rather it entails that the Mark-book system believes it. Is this consequence unacceptable?
It is certainly absurd that Mark comes to believe that Alpha Centauri A is bigger than the sun just by picking up the book from the shelf. But, it might not be so absurd if it is the Mark-book system, rather than Mark, that believes it. The idea that the John-room system understands Chinese is not very absurd, which is why the systems reply has been very popular in the Chinese room argument literature. The idea that the Mark-book system believes that Alpha Centauri A is bigger than the sun does not seem to be more absurd than the idea that the John-room system understands Chinese.