[hist-analytic] Response to Danny Frederick

Danny Frederick danny.frederick at tiscali.co.uk
Fri Aug 28 16:12:17 EDT 2009

Hi Bruce,


Thanks for your criticisms of my criticisms. Once again, I think you are
mistaken. I will explain why in a later message, though I will mention here
that much of the ground is covered by Williamson in his 'Conceptual Truth'
and some is covered by Kuhn in various places (e.g. 'Second Thoughts on
Paradigms' in his 'The Essential Tension'). But I will take up here the
issue about colours, since it can be dealt with largely independently of the
other stuff.


You said: 'We consider a determinate color A to be the same as a determinate
color B just when A and B are indistinguishable' (p.61).


I objected that determinate colours belong to the realm of objective fact
but distinguishability is relative to a subject. I went on to talk of
determinate colours in terms of wavelengths of light, but I needn't have
done so. Suppose (unrealistically) that my lawn is a uniform shade of green:
it has one determinate colour all over. But suppose I have some trees that
cast shadows over patches of the lawn. The bits of the lawn in shadow may
look dark green (or even grey) to me, while the bits in strong sunlight may
look light green (or even yellow). That is, I can distinguish the colours of
the two patches even though the two patches have the same determinate
colour. Another type of case is known as the 'spreading effect'. Have a
uniform shade of green painted in a straight line on a white piece of paper.
On one half of the line, paint thin black lines on either side of it. We see
this half of the line as being a darker green that the other half. Again,
colour A is (objectively) the same as colour B, but we can distinguish one
from the other. And the opposite happens too, as is well known: in poor
light different determinate colours may be indistinguishable.


In your last message you say that philosophers are almost always willing to
concede that nothing can have two different determinate colours [all over]
at the same time, colours being understood in an ordinary, nontechnical way.
You say that if, on reflection, I am not willing to concede this, I won't
mean what philosophers usually mean by 'determinate colours.'


I am willing to concede that nothing can be red all over and green all over
(using colour words in their ordinary non-technical senses). But if someone
denies it, that does not mean that he is changing the subject or using words
with a different meaning. Indeed if he IS denying it, then he must be using
words in the very same sense as I do yet entertaining something that I find,
at the moment, to be inconceivable. He may be able to show me that it is
possible by means of some novel thought experiment, in which case I will no
longer concede that nothing can be red and green all over. What we can
conceive at a particular time is a very poor guide to what is possible; it
just shows the limits of our imagination.


I am afraid I did not read your Appendices 2 and 3. I did intend to, but
there is a glitch on the site which means that the Appendices cannot be
downloaded (I notified Steve a few days ago). However, I have just
discovered that your whole book (including the Appendices) can be downloaded
in one go, by clicking on the title link. I never tried that until now. I
will re-read your chapter 3 and read your chapter 2 and the two Appendices
before I respond further.


Best wishes,



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