Question 041118c: Is the "Theory of evolution" a theory in the
scientific sense?
(last update:
Mar., 24, 2005)
Answer 041118c: A theory is not just some fancy idea, or something that
is unproven.
In order for a theory to count as a real scientific theory, some
criteria have to be fulfilled. And the "Theory of Evolution" does not
fulfill these criteria; so, in a sense, it does not qualify to be
called a theory.
In his best-selling book “A Brief
History of Time.” Hawking states, “A theory is a good theory if it
satisfies two requirements. It must accurately describe a large class
of observations on the basis of a model that contains only a few
arbitrary elements. And
it must make definite predictions about the results of future
observations.”
Popper, a 20th century philosopher, had a third requirement for an idea
to qualify as a theory: falsifiability.
That means that the theory should accomodate for an experiment that can
prove the theory wrong.
Thus a theory must be descriptive, predictive and falsifiable.
Furthermore,
it also should to be possible to prove the theory by some measurements.
In the following I want to examine some theories and discuss if the
these criteria fit.
1. Theory: the center of the earth contains one marshmallow
-descriptive?
No, the above sentence is a statement, not a theory. It will be
impossible in the forseeable future to directly
access the center of the earth. Furthermore, this statement is in
contrast
with another theory that the center of the earth is made of iron at
high
temperature and pressure. This theory cannot be proven directly, but
many measurements using seismographs indicate that the core of the
earth
indeed consists of iron.
Thus my marshmallow theory is not based on facts, nor is it
descriptive. It actually can be proven wrong, since no marshmallow will
stand the pressure and heat in the earth's core. most likely to exist
in the center of the earth.
2. Theory: two masses attract each other with a force proportional
to their mass and inverse proportional to the square of their distance.
F= a m / d2
where F is the force, a is a constant, m is the
mass and d2 is the distance squared.
This theory is called the general theory of gravity and was developed
by Isaak Newton.
-descriptive?
Yes, Newton realized that an apple when it falls from a tree is
attracted by the earth. This theory applied to all apples, and even to
all objects here on earth.
-predictive?
Yes, because we can be sure that any apple detaching from any tree on
earth in the future will fall down.
Furthermore, the orbits of the planets around the sun can be calculated
by applying Newton's theory.
- possible to prove?
Yes. One can design a fairly simple device, were a mass hangs down
suspended by a string. Bringing this mass near to a second mass, one
can measure
their mutual attraction by the deflection of a laser from an attached
mirror.
-falsifiable?
Yes. By performing the above described experiment at various distances
and various masses, one can find that the force indeed depends on the
mass and the inverse square of the distance.
All the criteria for a theory are fulfilled and are shown to be true.
The general applicability of this theory then lifts it to the rank of a
law
- the law of gravity.
Actually, very accurate measurements could show that Newton's theory
is not true. Due to the bending of time/space (this is covered by
Einstein's theory of relativity) by gravity, Newton's formula is not
100% correct. But the deviation is so small that for application in
everyday life, it can
be considered correct. But the deviations are observable, for example
in
the anomalies of the orbit of the planet Mercure.
With this example we can also see that a theory can be falsified by
another theory that can be proven and explains the facts better.
3. Theory: Only living organisms can produce organic chemicals
-descriptive?
Yes. Until 150 years ago chemists were unable to make artificial
organic compounds. Carbon compounds were though only to exist through
the action of living organisms on chemical compounds.
But this theory is difficult to prove, since somewhere, somehow an
organic compound could have been produced from inorganic compounds by a
chemical
reaction that does not involve a living organism.
-predictive?
Yes. Nobody should be able to make organic compounds from inorganic
ones. If one man succeeds, the theory will be proven to be wrong.
- falsifiable?
Yes. By making one, and one is enough, organic compound from inanimate
matter will prove this theory wrong.
And indeed, in the 19th century the German chemist Woehler suceeded to
make urea, an organic compound, from ammonium carbonate, an inorganic
compound.
Thus the theory that it takes a living organism to make organic
chemicals was proven to be wrong.
4. Theory: abiogenesis (life develops from non-life)
-descriptive?
Yes. Consider the following: A heap of garbage is thrown in a street
corner. A few days later the heap is full of cockroaches and rats. Thus
my theory is that they originated from some of the dirt and garbage.
It might even be possible to prove the theory. As many times as you
throw garbage in street corners, there will be rats in it a couple of
days later.
-predictive?
Yes, - and no. Whereever there is a heap of garbage, there will be
rats. So it is predictive.
But on the other hand, if you make sure that no rats can enter the heap
from outside, for example by putting it in a net, attaching it to a
string and suspending it from the ceiling, there will be no rats in the
net. So, it is not totally predictive.
-falsifiable?
No. And this answer might astonish you. Even if you make sure that no
rat enters your heap and you do not oberve any rats comming out, there
might be a heap of garbage somewhere in the world where rats develop
in, without coming from the outside. It is impossible to monitor all
heaps of garbage all the time all over the world. And even if you start
investigating all heaps from now on, there might have been one heap in
the past, were abiogenesis has occurred.
Thus this theory is not falsifiable. But still every rational person,
including scientists and medical doctors think that abiogenesis does
not occur. Simply because it has never been observed.
Sidenote:
That the theory of abiogenesis is thought to be wrong has very
important consequences.
It enables us to store food for a long time, for example. Pasteurized
milk can be kept for extended time, beause the heat treatment killed
germs in the milk.
It enables us to make surgery more safe by sterilizing the equipment
and intravenous drips. Once sterilized, the equipment will stay
sterilized,
and can be used without infecting the patient.
Housewives, medical doctors and the Food and Drug Administration know
that the theory of abiogenesis is wrong.
It was never observed that life springs forth from non-life.
It was never observed that bactetria develop in a completely sterilized
dish full of nutrients.
When you have a bacterial infection and doctors take a blood sample,
transfer it to a culture medium and find bacteria in that culture
medium
afterwards, doctors assume that these bacteria are the cause of your
disease.
No medical doctor will assume that these bacteria developed
spontaneously
in the culture medium on their own. If they would, they would not treat
you with the necessary antibiotics and you might die.
But the theory of evolution is in part exactly this abiogenesis theory.
The first living cell had to spring to life from non-life.
5. Theory: all swans are white.
-descriptive?
Yes. All swans that were found were white.
-predictive?
Yes. It predicts that all swans that will be found from now on will be
white.
-falsifiable?
Yes. The frist non-white swan that is found will falify the theory.
Actually, black swans do exist, thus this theory was proven to be wrong.
5. Theory, modified: all swans are white, and any non-white bird
cannot
be a swan
-descriptive?
Yes. All swans that were found were white.
-predictive?
Yes. It predicts that all swans that will be found from now on will be
white.
-falsifiable?
No. Because it a an oxymoron. This theory proves itself by circular
reasoning.
Even thought the theory is descriptive and predictive, it is not true,
but
it cannot be falsified, because it is an oxymoron.
I think now it is the time to investigate the last theory
6. Theory: the theory of evolution. Life started from non-life and
it
evolved, and is still evolving by the process of mutation and selection.
-descriptive?
Yes and no. It describes a model that explains the occurrence of life
and
its variety.
But the theory cannot correctly describe spontaneous generation. Living
cells are too complicated to have occured spontaneously. No evolution
model
can accomodate the spontaneous assembly of DNA, proteins and a cell
membrane
from "scratch".
No evolution model can explain the spontaneous formation of new genes,
that
are necessary for primitive life forms to evolve into higher ones.
-predictive?
No. With evolution, one can describe anything and everything.
-Organisms evolve from simple to complex, because mutation provides
better
species that are the "survival of the fittest".
-Organisms do not evolve and are in a state of stasis, snice they are
prefectly
adapted to their environment (e.g. sharks).
-Organisms evolve "back" (e.g. fish evolve into amphibians which evolve
into
mammals which evolve into whales, which are back in the sea and have
many
similar body plans of fish).
The prediction of future organisms is futile, since nobody can predict
the
"quirks of nature".
-falsifiable?
No. Because it a an oxymoron. This theory proves itself by circular
reasoning: life evolved "naturally" and only "natural" origin
of life will be considered. Thus life evolved.
But this does not mean that evolution is the only possible explanantion
for
the existence of life.
There can be other models, or theories that describe the same
phenomenon, the wide variety
of living things.
One promising candidate for an alternative model is the "Intelligent
Design"
idea, where an intelligent being designed and made living organisms.
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