[Phys-L] truth +- knowledge

[John Denker <jsd@av8n.com>]

On 02/04/2013 11:32 AM, Marty Weiss wrote:

> [The problem] is not that teachers teach science as "truth"... it is that
> teachers teach science (if they do at all, but that's a topic
> separate from this reply) as what it is...  messy and changeable.
> Students are brought up to regard things as "black and white"  their
> religion is inalterable;  politics nowadays is us or them.  So how
> can science be understood when it changes every time some scientist
> discovers something that contradicts what was supposedly set in stone
> years ago?   Listen to conversations in classrooms and on tv... "Why
> do you "believe" in evolution when Dr. X just found a fossil that
> goes against Dr. Y's theory?"   "You scientists don't know what's
> true... so why should any of it be true?" As if "truth" is
> inalterable and if anything is found not to have happened the way one
> scientist said it did then the whole thing is false.

I mostly agree with the sentiment, but I come at it from a slightly 
different direction.

  By way of analogy, in physics there are four or five mutually-
  incompatible definitions of "heat".  This might seem like a
  problem in theory, but I don't find it to be a problem in practice,
  because it is super-easy to bypass the problem.  Unanswerable
  questions about "heat" can be replaced by easily answerable
  questions about /energy/ and /entropy/.

So it is with "truth".  I find it helpful to distinguish "truth"
from knowledge.  As see it, scientists don't create truth, and 
they don't change the truth.  Instead, we create /knowledge/.
Controversial and/or unanswerable questions about "truth" can be 
replaced by easily answerable questions about knowledge.

By way of illustration:  Jupiter has a certain number of large moons.
The number of moons did not change in January 1610.  However, our
human /knowledge/ of the moons increased rather dramatically at
that time.  As a related point, the "truth" of the matter was the 
same everywhere on earth, whereas the knowledge was very unevenly 
distributed.

We build models that approximate the truth.  Some models work well, 
others not so well.  Because we deal in knowledge, not truth, arguing
about the exact definition of "truth" is very far down on the list
of priorities.  According to /any/ halfway-reasonable definition of
"truth", we don't know the "truth", so the exact definition doesn't
matter.

Even when it comes to Holy Scripture, the same logic applies.  If
somebody thinks that the Scriptures are "true" and unalterable, it's
not worth arguing the point.  It's much more worthwhile to realize
that the Scriptures are open to interpretation, and the interpretation
is most certainly alterable.

  In science, sometimes even the truth is alterable.  For example,
  over cosmological timescales, moons can come and go, and even
  planets can come and go.  So, the question of how many moons belong
  to Jupiter will never have an exactly, eternally "true" answer, 
  because nothing about the situation is eternal.

Anybody who goes looking for perfect "truth" is going to be bitterly
disappointed.  The folks who claim to have a monopoly on "truth" don't
have a very good track record.

As a constructive suggestion, I suggest people look for /knowledge/ that
will help them get along in an imperfect world.  Physics has a lot to
offer in this department.

In the real world, people make decisions based on imperfect information
every day.  For example, if I mail-order a pair of shoes, there is no 
chance that the shoes will "exactly" fit my feet, but so what?  Shoes
are made to be adjustable over a rather wide range.  Moreover, my 
feet are somewhat elastic, so there is some /tolerance/ involved
even for non-adjustable footwear such as cowboy boots.  As a last
resort, I can send the shoes back and exchange them for something
else.  There is some cost involved in returning stuff, so somebody
needs to bear the associated risk and cost.

The point is that the cost and risk associated with buying shoes is 
far less than the cost and risk of /not/ buying a sufficient number
of shoes.  Anybody who refuses to buy shoes until the exactly-right
shoe comes along is an idiot.

All of our knowledge is imperfect.  One should not over-react *or*
under-react to these imperfections.