From: "Tobin Nellhaus" <nellhaus-AT-gwi.net>
To: <bhaskar-AT-jefferson.village.Virginia.EDU>
Subject: BHA: Re: real def!
Date: Fri, 21 Nov 1997 20:38:13 +0200


Hi Howard--

Thanks for the "review of the lit" on real definitions.  I'd like to raise
some questions about one passage:

>And, Tobin, what about this one:  "The simple theory that things
>look blue because they are blue may then be replaced by the
>scientific theory that they tend to look blue in normal
>circumstances because they reflect light of wavelength 4400A.
>Subsequently we may allow the latter to define the scientific use
>of blue; in which case of course it is no longer contingent that
>blue surfaces reflect light of that wavelength" (RTS 177).

I have two concerns here.  The first we've discussed before, I think
privately: wavelengths, like other sorts of distance (and fluids), have no
natural breaks.  They form a continuum.  The Angstrom unit is based on some
more-or-less arbitrary or conventional choices, and I think the selection of
4400A for "blue" is also partly a matter of convenience.  This is
highlighted by the fact that various cultures do in fact identify colors
differently.  ("Red" is one of a very few special cases, since there is a
cross-cultural tendency to select a particular color as the "best example"
of red--a fact conditioned by the nature of our eyes.)

But this just tells us that this example is problematic.  I'm more concerned
about the possibility of a sort of circular reasoning in which our
definitions determine what exists, which this example could promote.  This
would be a logic which says that because scientists have defined "blue" as
4400A, therefore anything that reflects light of wavelength 4400A will
appear blue, therefore blue (or blueness) exists, independently of us.  In
this instance, the power of reflecting light of that wavelength exists, but
its reception as "blue" is a matter of human vision and cultural definition
in interactions with that light; the two are distinct.  For instance,
someone with a certain type of color blindness might see it as gray or
somesuch: for that person, "blue" doesn't exist, but light at 4400A does.

On the other hand, a couple of times we've had debates on this list deriving
from a certain reluctance to pursue the implications of "real definition,"
especially this aspect:


>The significant point is that once we have established that it is
>the possession of a particular structure or constitution that
>accounts for a thing's powers, then we come to define the kind of
>thing x is by reference to the structure:  "It is no longer
>contingent that hydrogen is a gas with a particular atomic
>structure; rather anything possessing that structure is hydrogen"
>(RTS 173).  The atomic structure gives a "real definition" of
>hydrogen.

I've occasionally called this the "If it walks like a duck..." thesis.  The
debates have arisen regarding the identification of social agents, and
minds.  (Uh-oh, is that Colin screaming in the background?)  I don't have
the energy to reopen those debates now, but one of these days....

---
Tobin Nellhaus
nellhaus-AT-gwi.net *or* tobin.nellhaus-AT-helsinki.fi
"Faith requires us to be materialists without flinching": C.S. Peirce





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