Re: Software Engineering and Dreamers

[Jonathan Guthrie <jguthrie@brokersys.com>]

Okay, the "personal attacks" (calling you a "fool" in public hardly
qualifies as a personal attack on Usenet, referencing the brouhaha
on various newsgroups over an article by Ousterhout as an example of
what I'm thinking of) are uncalled for, so here's what I really think.  

In comp.lang.ada Mathew Hendry <scampi@dial.pipex.com> wrote:
> : However, crocodiles moving planets around in some unstated arbitrary way
> : is useless to make predictions from.  Therefore, the theory makes no
> : predictions at all about planetary "behavior" (one could argue that it
> : cannot---after all, what happens if the crocodiles change their mind
> : about how to move the planets?)

> The predictions of the theory are the same, whether you accept it or not. Its
> predictions follow directly from its stated assumptions, as with any other
> theory, valid or not.

You don't seem to understand.  I will attempt to explain better.

The positions of the planets, which is all you seem to be talking about,
can be determined by Kepler's laws.  Those laws can be derived from
Newtonian dynamics while it is a postulate with this "crocodile
theory."  While it is possible to make other predictions than the future
positions of the planets from Newtonian dynamics, it is not possible to
predict ANYTHING using the theory that crocodiles move the planets by
whim and their knowledge of Kepler's laws EXCEPT the future positions
of the planets,

This is true "whether you accept it or not."

Therefore, your "crocodile theory" is inferior in predictive power to
Newton's theory of universal gravitation, which is what you seem to
be comparing it to.

Now, if you were to expand your "crocodile theory" to be something like
a "theory of universal crocodiles", I would point out that 

A) Newton doesn't attempt to explain where gravity comes from or how
it works so I'm as willing to accept your theory of gravitation as any
other that I've seen
and 
B) Changing the name isn't an explanation.

> Obviously, you would be a fool if you did accept the theory, but that's hardly
> the point. My intention was to illustrate the fact that theories are not
> simply blind prediction engines.

I know what you're point is.  That's why I started with a statement that
Ockham's razor isn't needed.  Ockham's razor is needed to select which
theory is preferred when you have theories of equal predictive power.  To
invoke it is to concede your point.  However, you have not demonstrated
to my satisfaction that your theory is equal in predictive power to the
laws of Newtonian mechanics (simply stating that it is won't fly---I'd
just as soon believe that someone always tells you the truth because they
say they do) and I am attempting to explain WHY that I'm not satisfied
with your "proof."

In a nutshell, it's because the "crocodile theory" only explains the
motions of the planets, while Newtonian mechanics governs EVERYTHING.

Well, okay, there is one other reason I don't like your example.  
It's really bogus to wave your hands by saying "you get the same
answers, okay?"  How do you know?  Are you psychically linked to
these crocodiles, or what?  What RAW DATA are you using to create
your theory with?  Where does it come from?  (This IS what you're
trying to demonstrate, which is why it's the "other reason.")

With all the competing theories out there, and all the very real
examples you could make of competing theories making identical
predictions with one being favored for emotional reasons, you came
up with a hypothetical one.  It just so happens that I agree with
you:  The value of theories is based upon more than their predictive
power.  Ockham's razor, for better or for worse, makes that sort of
selection a formal part of science.  However, I could come up with
a better example with my eyes closed.

In fact, you seem to be so attached to the hypothesis that I have an
emotional attachment to Newtonian mechanics that I might use your
posts to ME as an example of what you're trying to demonstrate.  

Further deponant sayeth not.

-- 
Jonathan Guthrie (jguthrie@brokersys.com)
Information Broker Systems   +281-895-8101   http://www.brokersys.com/
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