Hmm... I kind of like the scalp on the totem pole metaphor, seems
more multicultural ;-). Shhhhh..... the walls have ears. I really
don't want to go through sensitivity training AGAIN :).
In this post I was originally planning to bring things
back around to the "tautology problem" in evolution
since I was afraid some might not find much of interest
in the mechanics analogy. I think I'll save that for
another post. I do feel, however, that there is much to
be learned from this discussion of mechanics. For example,
mechanics has been around a long long time (since Aristotle)
and is much "simpler" and better understood than evolution.
In other words, if there are difficulties with the "tautology
problem" in mechanics then we should reasonably expect
to have some difficulties with evolution as well. But I
tend to agree with a point Del made earlier, if evolution
can be reduced to a meaningless tautology then mechanics
will suffer the same fate.
These general notions were reinforced when I took a look
at Elliot Sober's discussion of the "tautology problem"
in his book <The Nature of Selection>. In fact, Sober
actually uses Newton's law as an illustration, beginning
with the ominous
## 'A similar controversy has raged (or smouldered) in the
## philosophy of physics over the question of whether the
## consequence law "F = ma" is empirical or simply the
## definition of the idea of force.' -- Sober
Sober gives two references for further reading on this
controversy:
Earman, J. and M. Friedman (1973). "The Meaning and
status of Newton's Law of Inertia and the Nature
of Gravitational Forces," <Philosophy of Science>
40: 329-359.
Jammer, M. (1957). <Concepts of Force>, Cambridge:
Harvard University Press.
Sober seems to side with me on this, although it's
tough to tell with these philosophy types :-0. In any
event, he says "... two considerations have suggested,
if not decisively shown, that the proposition is
empirical." His considerations are much along the
lines I've already discussed, except he says it
much better, of course :). I did like his terminology
(source laws and consequence laws) which I think
helps in clarifiying the issues. I think this will
be especially helpful when looking at the "tautology
problem" in evolution. Basically, source laws are
things like Newton's universal law of gravity, Coulombs
law, the friction law I discussed earlier etc. The
consequence law is, of course, the second law itself.
DR:===
>You were probably right that I had read the Feynman excerpt too hastily,
>although there are some oddities there in light of which I could dig in
>for a bit longer. But in the interest of keeping the pedantry index on
>this list at a reasonable level (well, at least not raising it) I'll let
>it go.
>
>HOWEVER, I'm not about to budge yet on my main contention. Just to
>clarify, let me expand a bit, then get back to our direct discussion.
>What I want to claim is that in any genuinely rich theory (e.g., not
>merely phenomenological generalizations such as some of the classical gas
>laws), there is a stipulative - or definitional, or human choice -
>element. Such elements are not just arbitrary and purely armchair - they
>are partially (but only partially) shaped by empirical considerations.
>On the other hand, they are not simply *dictated* in any way by nature
>(contrary to positivists, etc.). The presence of such stipulative,
>definitional, choice elements does not in the slightest imply that the
>containing theories are at risk of degenerating into closed definitional
>loops (one of Feynman's suspicions, I think), nor does their presence
>compromise, much less remove, the empirical character of the theories in
>question - indeed, I tend to think that without such elements the
>theories involved would not be able to make full empirical contact with
>nature. But it does mean that at some point in the theory/nature link,
>there will be a stipulative, definitional component - the theory will not
>be some purely mechanical result of investigating nature.
>
don't disagree as much as it may seem at first. For
example, whenever you discuss general principles, such
as in the above paragraph, I find myself agreeing with
you. But when you give a specific example, I almost
always disagree. From this I suspect that we really
disagree on the relative importance of the stipulative
and dictational (empirical) aspects.
So, before going on, let me pose a question motivated
by the above observations, your example of mammals and
in particular your later mention of Kuhn. Do you think
that there are real patterns in nature which scientists
try to **discover** and explain by theory? Or do you
think that we impose a certain pattern that is not
really there by introducing various stipulative
elements? (i.e. do we make certain choices and then
organize our observations about those choices soas to
create or invent patterns that aren't really there?).
This reminds me of a nice Baconian quote I used to
put in my tag-line:
"God forbid that we should give out a dream of
our own imagination for a pattern of the world"
-- Francis Bacon
OK, so it's probably pretty clear how I would answer
the question. I really enjoyed reading Eldredge's
book <Reinventing Darwin>, perhaps because this is
such a crucial point in his approach (combined
with the fact that I agree with him!). For example,
he has statements like the following all through his
book:
=================
"...it is the patterns themselves that are most important.
They demand explanation, and that is the job of evolutionary
theory.
... These patterns, so characteristic of the large-scale
elements of life's history, are real and demand theoretical
evolutionary explanation. It is equally abundantly clear
that no manner of old-style, simplistic ultra-Darwinian
extrapolation can be of any use in addressing these major
patterns of evolutionary history."
-- Niles Eldredge
=================
Now back to mechanics, and I'll try to be brief :). The
best example of a stipulative element I can think of
are the definitions of position, velocity and acceleration.
These definitions make precise what is meant by "motion".
How far does this take us into mechanics? Not very far,
actually, and the best illustration of this is probably
our friend Galileo. Galileo concerned himself almost
exclusively with kinematics, i.e. the study of motion
irrespective of what causes the motion. What Galileo
sought were the laws of kinematics that describe the
motion of natural objects. Suppose you throw a ball
through the air. What path does it follow? Is the
velocity consant, proportional to time, to distance,
to time squared, to distance squared etc. etc. Now,
one can start out with any assumption (definition)
one likes, say v is proportional to distance squared,
and work out a theory of kinematics. Everything is
fine and dandy from a logical point of view. Its not
physics though unless the law actually describes the
way bodies move in nature. To discover this one must
go and look. This is what Galileo did with many careful
observations of balls rolling along smooth grooves in
inclined planes etc. And so I would have to insist
that the kinematical laws are real patterns in nature
and that they were discovered by Galileo and not invented.
Well, I hesitate a little to plunge into a discussion
of mass since mass is somewhat difficult to understand
precisely. In some ways there is a parallel to the above.
Like motion, we have an intuitive physical appreciation
for "quantity of matter" but require some precise definition
to actually make much progress. Oh, before I forget, you
are entirely correct in pointing out that Cohen's discussion
of force ratios was in a more general context of trying to
quantify what "quantity of matter" means. In any event,
we do need a precise definition of "quantity of matter",
however, this definition cannot be totally _ad-hoc_.
It has to correspond in some way to the physical notion of
"quantity of matter". Does relating "quantity of matter" to
inertia maintain this physical notion? It seems so to me.
So, there does seem to be, as you suggest, an element of
stipulation involved. But how much is stipulation and how
much is yanking mother nature's teeth out, er, I mean,
how much do we get by taking dictation from mother nature :)?
So we end up kind of where we started. I can agree in
a very general way, but your examples always seem to make
me fidget. For example, this statement makes me a bit
nervous:
DR:===
>That sounds awfully stipulative. We lay down the *condition* under which
>they *shall* have the same quantity - matching numbers *as determined by*
>the specified ratio. (As Cohen points out a bit earlier, Newton could,
>given his system, explain why weight and matter correlated so nicely in
>our neighborhood, but that is *given*, the system, which while justifying
>it we aren't.)
I would say this a bit differently. Newton *discovered* what
those before him only saw "as through a glass darkly" :).
He discovered the modern notion of mass as a (constant)
property of matter. Newton realized that the weight was
not a property of matter and was able to provide an
explanation why. IMO, this is one of many explanations
that serve to justify Newton's system, i.e. to suggest
that Newton unlocked (discovered) one of Nature's deep
dark secrets.
Well, I could continue to beat this over and over,
but I suppose we'll probably just end up having to
agree to disagree on the relative importance of the
stipulative elements of Newtonian mechanics.
Now to Kuhn ....
[...]
>DR:=====
>(Re: Cohen. I'm not sure exactly how much weight (sorry) to put upon
>his choice of words, but in his 1985 _Revolution in Science_, (p. 161)
>Cohen credits Newton with "invention of the primary concept of physical
>science (mass); invention of the concept and law of universal gravity
>....". Since Kuhn, the term 'invention' has been a bit vexed, but anyway
>Cohen does not use 'discovered', but credits Newton with *inventing* the
>concept which in _Birth_ he cited (as I read it) as - by stipulation -
>tying the system together across types of substance.)
>
>Well, have I helped my cause any?
>
You were doing great until this ! :). As an attempt at rescuing Cohen
from Kuhn I would key in on the word concept. The modern concept
of mass did not exist before Newton. So we might say he invented
the concept, though I would prefer to say he introduced the concept
into physics. Mass and inertia are real properties of matter
that were discovered not invented. [very dogmatic of me, eh? :)].
This reminded me of something I read awhile back, wish I could
remember the source. Some FemiNazi ;-) said that Newton's
Principia was really just a rape manual and that science would
be completely different if the pioneers of science had been
women instead of White European Men, i.e. women instead of WEMen :).
Well, I must say that this is a rather strange notion. Would
women scientists somehow manage to invent something other than
the inverse square law?
Perhaps I shouldn't comment on Kuhn since I've never read him.
I have read what some others have said about his ideas and it
seems to me that he tries to stretch things a bit too far.
In his book <One World>, Polkinghorne has a brief discussion
of Kuhn and, following that, of Feyerabend. He connects the
two with the following humorous comment:
"What in Kuhn was simply preposterous becomes in Feyerabend the
Theatre of the Absurd" -- Polkinghorne
Ooooh, I better quit now, said way too much already :).
Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University
"God forbid that we should give out a dream of
our own imagination for a pattern of the world"
-- Francis Bacon