[FOM] Type-Occurrence-Token

Ron Rood ron.rood at planet.nl
Tue Sep 27 11:47:06 EDT 2005

A.P. Hazen wrote on 23 sep 2005 at 10:10 (Europe/Amsterdam):

>     An occurrence of a symbol in a TOKEN expression is a token: in
> writing "cat" you will produce a physical object-- a thin,
> discontinuous, film of ink on part of your whiteboard, say-- and the
> occurrence of "a" in that token of "cat" will be a smaller physical
> object.

Hazen, like so many others, seems to assume that token expressions are 
physical objects—films of ink on paper, or chalk on a whiteboard. 
Maarten Janssen and Albert Visser provide an argument that, if sound, 
suggests that they are not.

To begin with, note that the idea that tokens are films of ink etc. 
suggest that one primarily has written language in mind. But consider a 
letter token on, e.g., a computer screen, for example, a letter in a 
window of a word processor. If one moves the cursor in front of that 
letter and subsequently types a space, then that letter moves one 
position to the right (or ends up at the beginning of the next line). 
Do we still have the same token? Janssen and Visser point out that our 
talk of "movement"  etc. suggests so. Similarly, if one selects that 
letter it will typically change from black against a white background 
to white against a black background. Do we still have the same token? 
Again, Janssen and Visser point out that our talk of "change" seems to 
suggest so.

Now, they proceed, what is moving or changing is not--not *really*, 
that is--a physical object. Hitting the space bar causes a change in 
the computer's internal state, which in turn causes a change on the 
screen. One can, for example, in principle make a letter move around 
the screen faster than the speed of light. Since no physical object can 
move faster than the speed of light, that letter token is not a 
physical object.

Janssen and Visser propose instead that token letters are something 
like visible contours on a suitable surface, contours that are not 
necessarily associated to physical objects having the relevant contours.

The reference is:

Maarten Janssen & Albert Visser, "Some words on 'word'",
(see pp.10-11).

Ron Rood

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