Last updated: 9/4/01
Some Aspects of Science
Characteristics of Science and the Philosophy of
Science
Science is a method of learning about the natural world - the world accessible
through our senses.
Let us here use "absolute" to describe knowledge which is assured and
unchanging, and "provisional" to indicate knowledge which is correct as far as
we know, but which is subject to change as we learn more. With these definitions,
scientific knowledge is provisional. In fact, one of the definitions of a scientific claim
to kn0owledge is that it can be disproved. However, if scientific knowledge in a certain
area is expanded and tested over a significant time, it becomes more like absolute
knowledge, but never becomes fully absolute. Scientific knowledge is constantly being
refined and expanding.
Science generally proceeds by observation or experimentation with the natural world,
then hypothesizing and theorizing about the experimentation, and then by expanding and
testing the theories. Theories, or ideas about nature which have been confirmed by many
experiments, are the most valued product of science, since they unite many facts and can
explain them. The Philosophy of Science seeks to explain the connection between
experiments and theories. How do experiments support or prove a theory, especially if the
theory can be falsified by a further experiment?
There is an underlying assumption about scientific knowledge, which is often implicit
or unspoken, that the natural world is real and not a figment of our imagination. This is
impossible to prove, but it does influence the choices that scientists make. This is also
the assumption that all of us make in our everyday lives - our pleasures and pains, our
joys and hangers are real and not something that w4e can simply change our minds about.
Before 1940, the dominant explanation for how science generates knowledge, and the type
of knowledge it generates, was called "Logical Positivism." Scientific
experiments were supposed to generate facts - things which were known to be true about the
natural world because they were simple, direct observations of it, not needing any theory
or interpretation. Scientific theories were statements uniting many facts, which were not
contradicted by any known facts. Under Logical Positivism, there was supposed to be a
uniform "scientific method" that consisted of a series of steps, such as
- Perform experiments.
- Hypothesize (guess) about the results
- Publish the results of the experiments and hypotheses to subject them to open criticism.
- Repeat experiments using similar and different methods, and perform further experiments
to test all of the implications of the hypotheses. For experiments, the results should be
consistent whether performed by believers in a particular hypothesis or by opponents of
that hypothesis; this is a standard of objectivity.
- Choose a theory from among the competing hypotheses based on simplicity, accuracy in
predicting the experimental results and the widest scope of experimental results that can
be explained. For example, Isaac Newton's theory that treats the earth (and objects n the
earth) and "the heavens" (Moon, planets, sun and stars) in the same way, is,
under this criterion, superior to earlier theories such as Galileo's, which treated these
two as entirely different.
- Continue to test the theory in all of its implications and extensions. A valid theory
with explanatory powers should be able to suggest new experiments that have not yet been
conceived of, and to predict their results.
In other words, science was viewed as a more or less automatic progress system.
Starting around 1940, Logical Positivism came under attach from the Post-Modernists.
Some of the points were simply aspects of science that Logical Positivism had swept under
the rug such as
- Due to progress in science, the results of experiments could no longer be viewed as
simple facts free of any theory. For example, we see through the lens of the eye, so in
order to trust sight we need to know about lenses. But how do we know about lenses? By
experiments with light, which come down to sight. So the logic was circular, while
experiments were supposed to be simple direct observations not dependent on any theories
or interpretation. Further, we need to know about nerves in order to understand how
information from the eye end up in the brain, and even today we do not know how the image
that we see is formed in the mind.
- When scientists discard an old theory in favor of a new one, the process is not the
calm, rational one foreseen in step 5 above. Often the evidence for the new theory is not
conclusive. It sometimes seems that a new generation of scientists simply abandons the old
theory. True, eventually overwhelming evidenced accumulates in favor of the new theory,
but the simple experimental evidence does not seem to be the only thing going on.
- One of the other things that goes on is that scientists are not the calm rational
white-coated automatons portrayed in TV commercials but are ordinary people with hopes and
fears, ambitions and secret vices. Bear in mind that making experiments, hypotheses and
theories is an intense type of activity. Although the scientific method as described above
has scientists standing outside of the hypotheses they are judging, when it comes right
down to it, scientists become committed to hypotheses, and they have favorites among the
experiments. One of the commonest misassumptions about science am0ong the general public
is that there is an enforced orthodoxy of views, and that dissent is not tolerated. In
actual fact, arguments among scientists are often fierce and bitter, with a full range of
views expressed. In fact, one of the concerns expressed by/both male and female scientists
who are interested in increasing the participation of women in science, is that arguments
among scientists are so fierce that younger women find it difficult to participate in so
competitive an enterprise. Some argue that scientific discussion must become gentler and
more cooperative, and that this will happen when more women become scientists, and that
science in fact needs this approach, and that is why more women scientists are needed.
Other argue that women must learn how to argue passionately. The point of mentioning this
is that scientists do not arrive at a consensus through a calm, dispassionate comparison
of experiments and theories, but through an open and vigorous debate, often between
partisans. By the time a consensus emerges, generally there has been a full and open
debate considering full range of facts (experiments) and hypotheses.
Further, Post-Modernists attacked science at the core - the connection between
experiment and theory. There is no basis for accepting scientific explanations as more
accurate than other types, such as religious or philosophical explanations. Accepting
experiments and the idea of a real world are articles of faith, just as a belief in God or
Natural Law are articles of faith.
All of this is true enough; as far as we can see now, there is no absolute knowledge
that is entirely free from all assumptions or articles of faith.
Expanding and intersecting spheres of scientific knowledge
One of the characteristics of science is that it is progressive - scientific
knowledge is cumulative and expanding. The figure below illustrates this.
Figure 1: illustrating how science is "progressive"
The figure shows an expanding ring of knowledge, moving out from a core in several
directions. Results (experiments and theories) at the outer edge of the ring are
uncertain, becoming increasingly more secure towards the inner edge. Material in the core
has been around long enough that major changes are rare, unless there is a "paradigm
shift." In a paradigm shift, the whole basis of the field is overthrown. Paradigm
shifts are also called scientific revolutions. An example is the shift in the first part
of the twentieth century from Newtonian physics to Einstein's Theory of Relativity.
Physics deals with objects, the forces between them, and the resulting motion. In
Newtonian physics, moving objects have a position in space that varies with time. Space
extends without limits in three dimensions, time is a separate thing from space
altogether, and objects can move at any speed at all. Objects have a mass or quantity of
inertia that does not change. This picture was highly successful, and is still the basis
for much of engineering - automobile design, to pick a locally important example. But
towards the end of the nineteenth century, as scientists studied the speed of light more
carefully, and light from distant stars, severe problems with this picture arose. The
result was the acceptance of the Theory of Relativity, in which space and time become
mixed together, the mass of an object increases if it travels close to the speed of light
(186,000 miles per second), no objects can travel faster than the speed of light in a
vacuum, and space does not extend forever but has limits. The result was a complete
conceptual overthrow of Newtonian physics; theis prevailing thoery was completely
replaced. Significantly, however, when the Theory of Relativity is applied to ordinary,
everyday objects that are moving much more slowly than the speed of light, then things
seem to obey Newton's version of physics. The result is that, while the foundation has
been replaced, the old results are still very accurate and useful, within a domain of
validity. A paradigm shift or revolution changes the foundation, but old results, which
after all had been thoroughly debated and tested, are still valid, within the domain for
which they had been tested.
What happens when two such circles expand to intersect? This happened in the nineteenth
century when electricity and magnetism, formerly considered independent of each other,
turned out to be related. In particular, it was discovered experimentally that electric
currents could cause magnetic fields (electromagnet). It was also found that changing
magnetic fields could cause electric voltages (generator). If there was not a real world,
these collisions could be fatal to scientific explanation, but instead in al such cases,
after some initial confusion and consternation, both fields united into a larger whole,
and a single explanation covered both cases, a benefit is terms of the Philosophy of
Science. Here is an illustration:
Figure 2: Formerly separate fields growing to intersect
What happened in this particular case is very interesting. Recall that electrical
changes can cause magnetic fields, and that changing magnetic fields could cause electric
fields. What if a changing electrical field caused a changing magnetic field, which in
turn cause a new electrical field? This indeed turned out to be the case, and once the
right changes were started, they could keep themselves "turned on", and they
would travel off. This turned out to be ordinary light waves! So two things that seemed
only distantly related, electricity and magnetisim, became intertwined, and formed the
basis for understanding a third field. Developments like these give much credibility to
science.
It is often incorrect to speak of "so-and-so's" theory of this or that (such
as Darwin's Theory of Evolution, Newton's Theory of Gravitation, Einstein's Theory of
Relativity). These names give honor to their founders, but almost always the original
version gets changed by later scientific developments. For example, the Theory of
Evolution by Natural Selection requires a theory of how traits are inherited, and theory
of genetics. Indeed, Darwin had such a theory, but it was incorrect and was never
accepted, and consequently his Theory of Evolution fell into disfavor during the later
nineteenth century, until the modern science of genetics, involving chromosomes and DNA,
was developed, and found to be wholly consistent natural selection. So Darwin's original
theory has been greatly modified. The theory is accepted, not because Darwin said it, but
because, with modification, it works.
In contrast, consider a recent development, the theory of cold fusion (not the Cold
Fusion web software), that fusion power could be extracted directly from low-power
reactions in water. There were some original exciting experimental results, but they could
not be reproduced reliably by others, and so it has fallen out of disfavor. There are
still a few scientists committed to cold fusion, but the scientific community has moved
on.
Science always requires positive evidence of a theory. Disproof of one hypothesis is
never proof of its alternative, even if that is the only alternative known at the time.
The alternative will naturally get increased attention. Equally likely is the rise of a
new alternative, and modification of the existing theory. If there is no satisfactory
theory, that is unfortunate, but scientists do not feel that they need to answer all
questions. There are clearly questions that are beyond the boundary in Figure 1. Questions
that are far beyond the boundary, including "ultimate" questions, are usually
not of scientific interest.
The public often looks for the latest scientific results, for diet, say. The
description above should make it clear that such early results may be unreliable; later
work may negate or greatly modify early results. A scientific consensus often develops in
the following sequence:
- Early results may not be believed by others, and there may be no great rush to see if
they can be validated.
- Eventually, other scientists than the original ones try similar experiments, with
variations. If these are not consistent with the original results, then the exact
experiment is tried. If repetition, with or without variation, is consistent with earlier
results, interest increases. Eventually the number of repetitions by good experimentalists
lends increasing credibility.
- Theorists start studying how to incorporate the new results. Existing theories may be
modified slightly, or there large modifications may be necessary. In the latter case, for
well-established and successful theories, further experimental verification, extending the
original results to similar cases, is required.
- The new results are successfully incorporated into theories, with or without
modification, and the new theories point to new experiments, new ways of testing the
theories. These experiments are done, and if the results are consistent with the theory,
then the theory gains a consensus.
- In areas affecting public health or public policy, a professional body may review the
field and issue public guidelines.
New results can be misleading for several reasons:
- Statistical results ("produced improvements in 30% of cases") are subject to
statistical uncertainty. Large numbers of cases result in small percentage errors.
However, initial results are often done with small numbers of subjects.
- Even if the results are not statisical in nature, early experiments often use new
techniques, and these may not have been fully developed.
- A statistical association ("thirty percent of smokers develop cancer"), even
if it is definite, between A and B, leaves open the possibility that A causes B, that B
causes A, or that both A and B are caused by something else, C.
Changing
Life on Earth, GST 2020, 4 cr
