The Imparity of the Parity Principle


Some recent authors suggest that the extended view fails because it does not follow from functionalism. For although functionalism can tell us whether a system is cognitive, it does not show whether such a newly identified cognitive system can be attributed to the very same subject. I argue that Clark and Chalmers can dodge this attack by claiming that the Parity Principle is essentially an analogy. In their crucial thought experiment, it can be argued that Otto’s notebook is similar to Inga’s biological memory in that they are functionally equivalent, and it seems that the only relevant difference between them is concerned with their being located inside/outside the skull/skin. Provided that Inga’s biological memory is part of Inga’s cognition, analogously, Otto’s notebook should also be regarded as part of Otto’s cognition. However, I argue that this alleged analogy does not hold because the location is not the only difference that matters. Otto’s notebook and Inga’s biological memory are taken as part of a whole for different reasons, and because of this, they actually belong to different kinds of wholes. Otto’s notebook is part of a whole because such a whole functions as a cognitive system, but Inga’s biological memory is part of a whole because it is within a “proper whole” whose boundary is determined by reproduction. As a result, the analogy does not really work.

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  1. 1.

    In this paper, “cognition” and “cognitive system” are used interchangeably.

  2. 2.

    Also see Rupert (2010).

  3. 3.

    See Miyazono (2017) and Farkas (2012).

  4. 4.

    For a detailed discussion of the extended self, see Baker (2009).

  5. 5.

    Olso (2011) has also pointed this out.

  6. 6.

    This “replace” talk can look inappropriate because the realizers of Inga’s biological memory can have different functions; some of these functions can be substantial with respect to the very cognitive process performed by Inga-notebook. Some might worry that my account of functionally integrated whole no longer holds in this case because this bit of realizers will be excluded. However, it poses no real threat to my central claim. Since in that case, our observation is that the realizers of Inga’s biological memory still play some essential role when Inga-notebook performs a certain cognitive task. According to my account, they just should be included in that functionally integrated whole. This suggests that the “replacement” should be understood on the functional level instead of the material level.

  7. 7.

    As is suggested in Rupert (2004).


  1. Adams, F., & Aizawa, K. (2001). The bounds of cognition. Malden: Wiley-Blackwell.

    Google Scholar 

  2. Baker, L. R. (2009). Persons and the extended-mind thesis. Zygon, 44, 642–658.

    Article  Google Scholar 

  3. Clark, A. (2007). Curing cognitive hiccups: A defense of the extended mind. The Journal of Philosophy, 104, 163–192.

    Article  Google Scholar 

  4. Clark, A., & Chalmers, D. (1998). The extended mind. Analysis, 58, 7–19.

    Article  Google Scholar 

  5. Farkas, K. (2012). Two versions of the extended mind thesis. Philosophia, 40, 435–447.

    Article  Google Scholar 

  6. Millikan, R. G. (1984). Language, thought, and other biological categories. Cambridge, MA: MIT Press.

    Google Scholar 

  7. Miyazono, K. (2017). Does functionalism entail extended mind? Synthese, 194, 3523–3541.

    Article  Google Scholar 

  8. Olson, E. T. (2011). The extended self. Minds and Machines, 21, 481–495.

    Article  Google Scholar 

  9. Rupert, R. D. (2004). Challenges to the hypothesis of extended cognition. The Journal of Philosophy, 101, 389–428.

    Article  Google Scholar 

  10. Rupert, R. D. (2010). Systems, functions, and intrinsic natures: On Adams and Aizawa’s the bounds of cognition. Philosophical Psychology, 23, 113–123.

    Article  Google Scholar 

  11. Sprevak, M. (2009). Extended cognition and functionalism. The Journal of Philosophy, 106, 503–527.

    Article  Google Scholar 

  12. Wheeler, M. (2010). In defence of extended functionalism. In R. Menary (Ed.), The extended mind (pp. 245–270). Cambridge: MIT Press.

    Google Scholar 

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I would like to thank Maria Alvarez, Lok-Chi Chan, Qiaoying Lu, Ruth Millikan, Jesse Mulder, Huiming Ren, Michael Smith, Peter Shiu-Hwa Tsu, Tung-Ying Wu, Liqian Zhou, and the anonymous referee for helpful suggestions and comments.

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Zhang, Z. The Imparity of the Parity Principle. Philosophia (2021).

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  • Extended mind
  • Parity principle
  • Analogy
  • Proper whole