Posted by
Bruce Sherwood on
Apr 08, 2012; 8:58pm
URL: http://friam.383.s1.nabble.com/So-Are-We-Alone-tp7425235p7448392.html
I find it highly implausible that anyone who sees the authority/value
of a god to be more appealing than the authority/value of the
scientific approach is going to challenge science on the basis of the
definition and use of "induction".
As to the source of my own beliefs about the world, they come from
observing a coherent pattern of observations, with accompanying
unified explanations and predictions. There is no simple statement
that can be made about this, but coherence and unification are
crucial. A simple example is that once upon a time there was a thunder
god responsible for thunder, and a lightning god responsible for
lightning. It is possible that this is the correct explanation for
thunder and lightning, but for me it is vastly more satisfying to have
one explanation and mechanism that coherently explains both. In
addition, the science that explains thunder and lightning not only
unifies these two seemingly distinct phenomena but explains many other
phenomena as well, and one doesn't even need the existence of special
thunder and lightning gods.
In our physics textbook we have a lengthy case study about spark
formation in air. We first introduce a couple of intuitively appealing
models and then show that the predictions of these models are off by
many orders of magnitude in explaining/predicting the strength of
electric field required to create a spark in air. We then introduce a
third model which has the virtue despite its simplicity of predicting
approximately the observed value of the critical field strength. This
doesn't mean the model is "right", but at least we've shown the first
two models to be wrong, a non-trivial and valuable contribution.
But then there's a kicker. We ask a different question, a question
that played no role in the discussion up to this point: How would the
critical field strength change if the air pressure were doubled? The
first two models, discredited on the earlier grounds, predict that the
critical field strength should be independent of the air pressure. The
third model however predicts that the critical field strength should
double. It happens that this is in fact observed (and high-pressure
gas is sometimes used as a good insulator). That the model correctly
predicts a phenomenon that was not considered previously lends (to me)
additional credence to the explanatory power of the third model. This
is an example of coherence. "Belief" (if that is even the right word
to use) is strengthened by coherence, that many seemingly diverse
phenomena are explainable starting from a small number of fundamental
principles (and this coherence of course also strengthens one's
"beliefs" in the universal character of those fundamental principles).
I see this as much more than the kind of belief that the Sun will rise
tomorrow because it has risen so many days in the past. That's just
repetition of the same thing, whereas coherence is the linking of what
on the surface seem like different things.
Another example from our intro physics textbook: Early in the
mechanics portion of the book we introduce the simple
"ball-and-spring" model of a solid, where the "balls" are the atomic
masses (mainly the nuclei) and the "springs" are a model for the
electric interatomic forces, justified by the fact that to stretch a
metal twice as much requires (for small stretches) twice the applied
force, and a force proportional to a stretch is true of macroscopic
springs. On the basis of how much a metal wire stretches when a force
is applied, we're able to deduce the stiffness of the interatomic bond
in that metal, modeled as a spring. From this "spring" stiffness we
show how to predict accurately the speed of sound in a metal. No
student comes to the course imagining that there is any connection
whatsoever between stretching a wire and the speed of propagation of a
disturbance in that metal. Coherence. And later in the course students
are able to predict the temperature dependence of the heat capacity of
the metal, just from the atomic mass and "spring" stiffness. Again, no
student would expect that the temperature dependence of the heat
capacity of a metal, the speed of sound in the metal, and the stretch
obtained when applying a force to a wire made of that metal, could all
three be understood in terms of a simple atomic model of a metal and
fundamental physics principles. Enormous coherence.
For me, the great beauty of the concept of biological evolution is its
exceptionally strong coherence. It explains this, and that, and that ,
and that......
Bruce
From the Wikipedia article on Laplace:
An account of a famous interaction between Laplace and Napoleon is
provided by Rouse Ball:
Laplace went in state to Napoleon to present a copy of his work, and
the following account of the interview is well authenticated, and so
characteristic of all the parties concerned that I quote it in full.
Someone had told Napoleon that the book contained no mention of the
name of God; Napoleon, who was fond of putting embarrassing questions,
received it with the remark, 'M. Laplace, they tell me you have
written this large book on the system of the universe, and have never
even mentioned its Creator.' Laplace, who, though the most supple of
politicians, was as stiff as a martyr on every point of his
philosophy, drew himself up and answered bluntly, Je n'avais pas
besoin de cette hypothèse-là. ("I had no need of that hypothesis.")
On Sun, Apr 8, 2012 at 12:23 PM, Nicholas Thompson
<
[hidden email]> wrote:
> Hi doug, and Bruce
>
> I realize that the following was hundreds of words deep in a verbose email
> message, and so it is understandable that you did not respond, but I am
> curious about your response.
>
> I think we either have to be prepared to say why our faith [in induction]
> is better than their [faith in God], or be prepared to be beaten all the way
> back into the Dark Ages. Hence my interest in the problem of induction.
>
> Also, I was curious about your comment that you were not all that keen on
> induction. Can you describe how, if not by induction, you come to believe
> things.
>
> Nick
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