harnad@mind.UUCP (06/27/87)
In responding to Cugini and Brilliant I misinterpreted a point that
the former had made and the latter reiterated. It's a point that's
come up before: What if the iconic representation -- the one that's
supposed to be invertible -- fails to preserve some objective property
of the sensory projection? For example, what if yellow and blue at the
receptor go into green at the icon? The reply is that an analog
representation is only analog in what it preserves, not in what it fails
to preserve. Icons are hence approximate too. If all retinal squares,
irrespective of color, go into gray icons, I have icons of the
squareness, but not of the colors. Or, to put it another way, the
grayness is approximate as between all the actual colors (and gray).
There is no requirement that all the features of the sensory
projection be preserved in icons; just that some of them should be --
enough to subserve our discrimination capacities. This is analogous to
the fact that the sensory projection itself need not (and does not,
and cannot) preserve all of the properties of the distal object. To
those it fails to preserve -- and that we cannot detect by instruments
or inference -- we are fated to remain "blind." But none of this
information loss in either sensory projections or icons (or, for that
matter, categorical representations) compromises groundedness. It just
means that our representations are doomed to be approximations.
Finally, it must be recalled that my grounding scheme is proposed in a
framework of methodological epiphenomenalism: It only tries to account
for performance capacity (discrimination, identification,
description), not qualitative experience. So "what it is like to see
yellow" is not part of my evidential burden: just what it takes to
discriminate, identify and describe colors as those who see yellow do...
--
Stevan Harnad (609) - 921 7771
{bellcore, psuvax1, seismo, rutgers, packard} !princeton!mind!harnad
harnad%mind@princeton.csnet harnad@mind.Princeton.EDUfranka@mmintl.UUCP (Frank Adams) (07/02/87)
In article <923@mind.UUCP> harnad@mind.UUCP (Stevan Harnad) writes: |In responding to Cugini and Brilliant I misinterpreted a point that |the former had made and the latter reiterated. It's a point that's |come up before: What if the iconic representation -- the one that's |supposed to be invertible -- fails to preserve some objective property |of the sensory projection? For example, what if yellow and blue at the |receptor go into green at the icon? The reply is that an analog |representation is only analog in what it preserves, not in what it fails |to preserve. I'm afraid when I parse this, using the definitions Harnad uses, it comes out as tautologically true of *all* representations. "Analog" means "invertible". The invertible properties of a representation are those properties which it preserves. Is there some strange meaning of "preserve" being used here? Otherwise, I don't see how this statement has any meaning. -- Frank Adams ihnp4!philabs!pwa-b!mmintl!franka Ashton-Tate 52 Oakland Ave North E. Hartford, CT 06108