[hist-analytic] sticks, circles and the contingent a priori
Roger Bishop Jones
rbj at rbjones.com
Mon May 31 10:28:07 EDT 2010
On Monday 31 May 2010 14:23, you wrote:
> The distinction I was drawing is not, I don't believe
> anyway, a distinction between physical and nonphysical
> quantities. I can use degrees in figuring out physical,
> spatial, relations in real time; such as how far an
> airplane will travel if it is a certain bearing and
> velocity. The issue concerns how we introduce units of
> quantity, not whether the quantities are physical or
> not. No matter which rotation we are talking about we
> get the same values, e.g. for the trigonometric
> functions. But if we pick a different stick we get a
> different "meaning" of 'one meter'. 'One degree' is not
> dependent on any particular circle; but 'one meter'
> depends on one particular stick. That is the critical
Well I think I understand your point, and I still think that
the difference you are pointing to here can be accounted for
by the fact that the former is and the latter is not a
standard for a physical quantity, and that the notion of
dimension is helpful in distinguishing whether something is
a physical quantity or not.
An alternative way of thinking of it is that measures for
angles are definable in a pure mathematical context, in much
the same way that the number pi is definable in that way
(also defined in terms of circles but dependent on no
> Now I don't discuss this in the book; but I
> do take Kripke to task for what I believe is an
> equivocation that leads to the erroneous belief that
> there is a contingent a priori in any non-Kantian sense.
> I point out on this matter that Kripke is anticipated by
> Reichenbach, among other things.
Oh, well I misunderstood you there.
Are you now saying that there are contingent a priori truths
in the sense of Kant? (and that this isn't just a different
equivocation?). I knew about the synthetic a priori in Kant
(arithmetic and geometry for example), but not the
contingent a priori (arithmetic and geometry still being
Are you saying that Reichenbach anticipated Kripke's error?
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