cugini@ICST-ECF.ARPA.UUCP (06/02/87)
S. Harnad writes: > Now I conjecture that it is this physical invertibility -- the possibility > of recovering all the original information -- that may be critical in > cognitive representations. I agree that there may be information loss in > A/A transformations (e.g., smoothing, blurring or loss of some > dimensions of variation), but then the image is simply *not analog in > the properties that have been lost*! It is only an analog of what it > preserves, not what it fails to preserve..... > > A strong motivation for giving invertibility a central role in > cognitive representations has to do with the second stage of A/D > conversion: symbolization. The "symbol grounding problem" that has > been under discussion here concerns the fact that symbol systems > depend for their "meanings" on only one of two possibilities: One is > an interpretation supplied by human users -- "`Squiggle' means `animal' and > `Squoggle' means `has four legs'" -- and the other is a physical, causal > connection with the objects to which the symbols refer. .... > > The reason the invertibility must be physical rather than merely > formal or conceptual is to make sure the system is grounded rather > than hanging by a skyhook from people's mental interpretations. I wonder why the grounding is to depend on invertibility rather than causation and/or resemblance? Isn't it true that physically distinct kinds of light (eg. #1 red-wavelength and green-wavelength vs. #2 yellow-wavelength) can cause completely indistinguishable sensations (ie subjective yellow)? Is this not, then, a non-invertible, but nonetheless grounded sensation? When I experience something as yellow, I have no way short of spectroscopy of knowing what the "real" physical characteristics are of the light. Nonetheless, I know what "yellow" means, as do young children, scientifically naive people, etc. I don't have a ready-made candidate to substitute for invertibility as a basis for symbol-grounding, although I suspect, as mentioned above, that causation and resemblance are lurking around somewhere. But how can invertibility serve if in fact our sensations are, in general, not invertible? John Cugini <Cugini@icst-ecf.arpa> ------