Nick, One of the most attractive things about your posts is how charming they are. They are so well written! Thank you for keeping the discussion at such a civilized and enjoyable level -- even when I don't agree with you.
-- Russ Abbott Professor, Computer Science California State University, Los Angeles On Sat, Apr 27, 2019 at 9:44 AM <[email protected]> wrote: > Frank writes: > > I would hate to have to demonstrate that a modern computer is an instance > > of a Turing Machine. Among other things they usually have multiple > > processors as well as memory hierarchies. But I suppose it could be > done, > > theoretically. > > First a passage from a chapter I contributed to a book edited by a > graduate student Nick knows (Zack Beckstead); I have cut out a bit in the > middle which aims at a different point not under consideration here. > ===begin=== > If talk of “machines” in the context of the human sciences seems out of > place, note that Turing (1936) actually introduces his “automatic machine” > as a formalization (thoroughly mathematical, though described in > suggestive mechanistic terms like “tape” and “scanning”) of “an idealized > *human* calculating agent” (Soare, 1996, p. 291; italics in the original), > called by Turing a “computer”. [...] As Turing remarks, “It is always > possible for the computer to break off from his work, to go away and > forget all about it, and later to come back and go on with it” (1936, p. > 253). It seems to me that then it must also be “always possible for the > computer to break off” and never “come back” (in fact, this often happens > in the lives, and invariably upon the deaths, of non-idealized human > calculating agents). > ===end=== > Of course Turing's idealization of "an idealized *human* calculating > agent" also idealizes away the fact that human computers sometimes make > errors. A Turing machine doesn't make errors. But both the processors and > the memory of a modern computer can, and *must* make errors (however > rarely, and however good the error-detection). To at least that extent, > then, they are not *perfect* instantiations of Turing machines. On the > other hand, that very fact about them makes them (in some sense) *more* > like (actual) human calculating agents. > > So, Nick, why are you asking what Turing machines think, instead of what > modern computers think? (Be careful how you answer that...) > > > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College > to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com > archives back to 2003: http://friam.471366.n2.nabble.com/ > FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove >
============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com archives back to 2003: http://friam.471366.n2.nabble.com/ FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
