Re: nature -> "human brain" -> "language terms" ==>> knowledge ?
Jay,
The issue that Alex raised concerned the use of
the words "objective" and "subjective" to classify
different ways of describing the same phenomena.
I made the point that the distinction is very hard
to define precisely and that any discussion that
involves those terms would be clearer if those words
were avoided.
Your example is an excellent illustration of my point:
JH> objectively the penny is circular. Subjectively it
> appears elliptical (say). Reconciling or explaining the
> difference between those judgments remains a difficulty
> for philosophy, and is even a matter of urgency in AI.
> What needs to be explained is the difference between those
> statements; there is a difference between appearance and
> reality, unless I am deceived.
I would describe the example in a way that is independent
of the nature of the perceiver, which could be a human, an
animal, or a robot. Following are the conditions:
1. There is an object X, whose image projected on a 2-D
surface (retina, film, screen, etc.) is elliptical.
2. Multiple projections of X on different 2-D surfaces at different
angles and distances produce ellipses of different sizes and shapes.
3. Under the assumption that X is a rigid body whose size and
shape is constant, all the projections can be reconciled by
a model of X as a thin circular cylinder of a thickness h and
radius r (where h and r are computed from the projections).
This analysis illustrates my point: Alex wanted to use the words
"objective" and "subjective" as a basis for drawing further conclusions.
He has every right to use the words as he prefers. But I was making
the point that those words (or the associated concepts) are too vague
to support detailed analysis. The analysis I just gave avoids any
problems one might encounter in AI or philosophy.
John