From: Shawn McCaslin
Dear Mr. Korn:
Here (appended below) are my comments regarding this web page:
> There is also scientific knowledge, things taught in science
> classes, which it is fair to call science.
-- Processes for creating models for prediction/control
of the natural world,
-- Models produced by those processes, and
-- Applications of those models.
> The scientific method is to test hypotheses by observing the real
> world while using whatever means are practical to reduce the
> of arriving at false conclusions.
The Scientific Method is a process for creating models for
cause or classification. There are other methods that are
scientific that apply to other types of problems.
Here (appended below) is an example application of the
Scientific Method to a question of cause.
> The basis of science is to determine what is true, not by what
> the greatest authorities claim, or by what would be true in the
> ideal universe, or some magical revelation or inner feeling,
> but by what actually happens in the real world.
Science has no necessary bearing on reality. It only
produces models that are useful.
Your brain could now be connected to a supercomputer
that is feeding you synthesized perceptions. You have
no way of knowing otherwise.
Science is defined by utility. It is useful for prediction and
control, regardless of whether it has any bearing on reality.
> A good scientific hypothesis should be predictive
To be scientific, models must be predictive.
> its truth can be judged by whether things it predicts come true.
> It is hard to see these as predictive, since they concern things
> that happened long ago.
You live only in the present instant. The past is just models
and memories. Scientific models regarding the past have value
precisely and necessarily because of their predictive power.
> Scientists will often use correlation to suggest a hypothesis that
> one thing causes another, but they cannot prove causality is true
> using only correlation.
You can never prove causality in the natural world.
> Extraordinary claims require extraordinary evidence
Your decision to rely on any particular scientific model is
ultimately, necessarily, a value judgment.
The evidence that you require to rely on any particular model
is dependent on the circumstances and your values.
For example, how much evidence do you need for antropogenic
global warming before you decide to make the hard sacrifices that
that are necessary for mitigation?
Test for Cause: Why is the sky blue?
The sky is blue because air is blue, like a piece of blue glass.
As scuba divers observe, sunlight in water becomes bluer with
i.e., water strongly absorbs red light. Maybe air, or at least water
vapor in the atmosphere, has the same effect.
The same part of the atmosphere that looks blue at mid day looks
to other observers at other locations on Earth at sunrise/sunset.
Also note that red sunlight photons in water are absorbed, whereas
sunlight photons in the atmosphere are still observed at sunset.
The sky is blue because light is refracted at the
interface, like sunlight is refracted by water droplets to form a
Refraction is a function of angle of incidence. Sunlight enters
atmosphere at a wide range of angles, but the sky looks uniformly
blue at mid-day. The sky/sun appears reddish at sunset/sunrise,
even where the sunlight is nearly perpendicular to the atmosphere.
The sky is blue because sunlight is reflected off of the oceans,
which are blue.
The sky is the same color in the middle of the Pacific or
Oceans as it is in the middle of Asia. Also, the oceans do not
change color at sunrise or sunset.
The sky is blue because air fluoresces blue (e.g., UV light is
absorbed and re-emitted at longer wavelengths).
The same part of the atmosphere that looks blue at mid day looks
red to other observers at other locations on Earth at
The sky is blue because sunlight is scattered by dust in the air.
Dust in our solar system that causes the zodiacal light has a
small effect on the color of sunlight that it reflects.
Sunrise/sunsets near population centers with high levels of air
pollution are similar to sunsets very far from those population
However, very fine dust, aerosols, and sulfur dioxide produced by
volcanoes have been linked to changes in sunrise/sunset colors.
Also, reflection nebulae in our galaxy often appear bluer than
the corresponding illuminating stars.
The sky is blue because sunlight is scattered by air molecules
fine aerosols more strongly at short (bluer) wavelengths.
The sky at sunset is orange/red because the sunlight directly
from the sun travels through more atmosphere than when the sun is
overhead, allowing more blue light to be scattered away.
None. This is the most widely accepted model of why the sky is blue.
Thanks for your comments.
You seem to be suggesting alternatives to my statements about science.
Generally I agree with what you say, but I prefer my current
for the purposes of this website. I'm aiming at people who might
science is just another belief system or that some quack medicine has
scientifically proven or that some new age guy spouting terms from
mechanics is being scientific. I'm not trying to
debating obscure points.
You don't seem to like it when I talk about "truth" or "reality".
Personally I think the idea that truth really consists of models that
(have utility) is very valuable, especially in tricky philosophical discussions, but it
would make the discussion here far more confusing. The same with
that we may be part of a simulation or a brain in a bottle.
would divert attention from far more practical concerns.
By proof of causality I'm not talking about deductive mathematical
The word "proof" is commonly used for establishing an assertion strongly
enough that people are willing to assume it with a lot of
I'm saying here is you can get that kind of confidence with replicated
controlled experiments, but not with correlations.
Your global warming example raises an good issue. Good scientists
that models have issues of accuracy and of course "values" will come
play when deciding how much confidence is needed before taking various
actions. I don't like to think of it as deciding to rely on a
model or not,
but as one of deciding how strong the evidence provided by a model is
not a true/false issue as much as a "how good" issue). Ideally
be done by analyzing the evidence behind the model and comparisons to
My description of the scientific method as attempting to avoid false
conclusions is meant to address the fact that there is no single method
can be applied to fields as diverse as physics, medicine, astronomy, and
anthropology, but in all cases what distinguishes science from other
of thought is that a lot of effort is given to eliminating known
Your blue sky example points out something that maybe I should talk
more, and that is actively looking for refutations of hypotheses.
it some thought.
Thanks for your thoughtful reply.
> You don't seem to like it when I talk about "truth" or "reality".
Right. And I don't think this is a subtle, philosophical quibble.
I think that the widespread equating of 'utility' with 'truth'
is a key reason why there are people on the Texas State Board
of Education who feel compelled to have their religion taught
in science class. The problem is that some people really mean
truth when they say truth. It is their truth versus scientism.
> Personally I think the idea that truth really consists of models
> that work (have utility) is very valuable, especially in tricky
> philosophical discussions, but it would make the discussion here
> far more confusing.
What if you just used 'useful' instead of 'true'? That way
you could reserve 'true' for when you really mean 'true'.
> The same with the idea that we may be part of a simulation
> or a brain in a bottle. Addressing this would divert
> from far more practical concerns.
I agree that you could skip that issue. However, it would
likely be obvious that you are avoiding 'truth', and
readers would likely wonder why.
> By proof of causality I'm not talking about deductive mathematical
But those are very different, potentially inconsistent things.
I don't see why they cannot be kept distinct.
> My description of the scientific method as attempting to avoid
> false conclusions is meant to address the fact that there is no
> single method that can be applied to fields as diverse as physics,
> medicine, astronomy, and anthropology, but in all cases what
> distinguishes science from other kinds of thought is that a lot
> of effort is given to eliminating known sources of error.
But such efforts improve reliability, and thus utility--i.e.,
value. Utility is the ultimate judge of scientific 'truth'.
I agree that the word "truth" is sometimes taken to mean absolute
some people claim they get from revelation. I certainly don't
to think that's what I'm talking about. On the other hand I don't
good alternative. A trouble with "utility" is that it could be
with the idea of practical application, and I don't want people
thinking some idea must have some obvious application for it to be
I'm not too worried that my use of "truth" will be misunderstood given
context of the article. Clearly the word is used everyday in a
non-grandiose way - "Are you telling me the truth about where you were
night?" or "It's true that aspirin has some harmful side
effects." I assume
that, like me, you tend to talk a lot with people who are upset about
religious zealots, and in those circles the word truth is likely to
connotations. But I think the great majority of people will
accept the word
in the more ordinary sense.
You did get me to reread the article for the first time in a long
I did find I used "truth" so often it started to grate on me.
revising this on my list of things to do. You still might not be
the result, but hopefully it will be a little better.
> I'm not too worried that my use of "truth" will be
misunderstood given the
> context of the article. Clearly the word is
used everyday in a
> non-grandiose way
I agree that there really
isn't a good alternative.
But I do think that 'truth' is frequently taken
even by people who are not conventionally religious.
I'll put revising this on my list of things to do.
> You still might not
be happy with the result,
> but hopefully it will be a little
I would be happy to review your revision (ignoring
we have already discussed) if you
I'll let you know when I post a new version and you can give me
thoughts. I'll try to do it within a few weeks.