Re: Is It True What They Say About Tarski?

Daniel Fabulich (
Sun, 24 May 1998 03:35:55 -0400 (EDT)

On Sat, 23 May 1998, Christian Whitaker wrote:

> Curiously enough, although nobody would do so, this statement would be
> acceptable in ordinary lenguage, but is nonsensical in a precise
> metalanguage, because of some problems encountered from specifying an
> exact time. I'll make a few more points before I go back to this.

Er, good point. Not thinking in a metalanguage leaves you prone to these
sorts of errors. Instead, you might add statements of precision to each
of your values, or simply presume that each of these values were precise
to their least significant digit.

> This is not a sustainable argument because the more information we had
> the weaker this definition of blue would become.

I wholeheartedly disagree. If blue were defined to be any light within
the wavelengths 549nm and 551nm (where both of these values have perfect
precision; they are simply part of our definition after all) then the
definition of blue cannot become stronger or weaker. More information
will only tell us whether certain wavelengths (ie 551.00 +/- 1nm) are, for
example, truly blue. Not that this is a particularly USEFUL definition,
of course, but you get the idea.

(On an unrelated note, is 550nm really blue? That number sounds wrong,
for some reason...)