Philosophy of Computer Science

Position Paper #3:

Is the Brain a Computer?

Last Update: 24 February 2010

Note: NEW or UPDATED material is highlighted


For this position paper, I would like you to evaluate the following "complex" argument.
(It's "complex" because it consists of 3 "sub"arguments, two of which treat the conclusions of previous ones as premises.)

  1. Turing's Thesis: A physical object can compute if and only if it can do what a (Universal) Turing Machine (TM) can do.

  2. A computer is any physical device that can compute. (Consider this as a (proposed) definition of ‘computer’.)

  3. The human brain is a physical object that can do what a (Universal) TM can do.

  4. Therefore, the human brain is a computer.

  5. Microsoft Word is TM-computable. (I.e., a Universal TM can execute Microsoft Word.)

  6. Therefore, any computer can execute Microsoft Word.

  7. Therefore, the human brain can execute Microsoft Word.

As usual, to evaluate this argument, you must determine whether (I) it is valid and whether (II) all the premises are true.

  1. To determine whether the argument is valid,
    you must suppose (or make believe) "for the sake of the argument" that all the premises are true,
    and then consider whether the conclusions logically follow from them.
    (Or: Can you imagine some way the world might be so that the premises are true but the conclusion is false?)

  2. It may be too difficult to determine whether each premise is true or false.
    More realistically, you should decide whether you believe, or agree with, each premise,
    and you must explain why you do or don't.

Finally, do you agree with the conclusion(s)?
If you do, but you think that there's something wrong with the argument, try to present a better one.
If you don't agree with the conclusion(s), state why, and try to give an argument for what you do believe.


  1. Your position paper should be approximately

  2. Please bring to lecture on the due date.

  3. At the top of the first page, please put the following information in the following format:

  4. For general assistance with writing (including my preferred method of paper preparation and format, as well as advice on grammar),
    see my website "How to Write".
    As before, no abstract is needed for this position paper, but you do need to give full citations to any sources that you cite.

DUE AT THE BEGINNING OF LECTURE, MONDAY, MARCH 15



Copyright © 2010 by William J. Rapaport (rapaport@buffalo.edu)
http://www.cse.buffalo.edu/~rapaport/584/S10/pospaper3.html