Theory and observation
In terms of the philosophy of science, the most important approach
to gathering and analysing information was the 'inductive method'. This was
championed by Francis Bacon, and then by Thomas Hobbes (1588-1679) and became
the basis of the Newtonian world of science. In its practical approach to
sifting and evaluating evidence, it is also reflected in the empiricism of
Hume (see p.21. Indeed, it was the inductive method that distinguished 'modern'
science from what had gone before, and brought in the first of the two major
shifts in world-view.
The inductive method
This method is based on two things:
1 The trust that
knowledge can be gained by gathering evidence and conducting experiments
i.e. it is based on facts that can be checked, or experiments that can be
repeated.
2 The willingness to set aside preconceived views about the likely
outcome of an experiment, or the validity of evidence presented, i.e. the
person using this method does not have a fixed idea about its conclusion,
but is open to examine both results and methods used with an open mind.
With the inductive method, science was claiming to be based
on facts and on open-mindedness, and as such was seen to be in contrast to
traditional religion, which was seen to be based on doctrines that a person
was required to accept and which were backed up by authority rather than
reason alone. In practice, the method works in this way:
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Observe and gather data (evidence, information), seeking to
eliminate, as far as possible, all irrelevant factors.
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Analyse your data, and draw conclusions from them in the form
of hypotheses.
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Devise experiments to test out those hypotheses, i.e. if this
hypothesis is correct, then certain experimental results should be anticipated.
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Modify your hypothesis, if necessary, in the light of the
experiments.
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From the experiments, the data and the hypotheses, argue for
a theory. Once you have a theory ,you can predict other things on the basis
of it,by which the theory can later be verified or disproved.
It is clear that this process of induction, by which a theory
is arrived at by the analysis and testing out of observed data, can yield
at most only a high degree of probability. There is always the chance
that an additional piece of information will show that
the original
hypothesis is wrong, or that it only applies within a limited field.
The hypothesis, and the scientific theory that comes from it, is therefore
open to modification. Theories that are tested out in this way lead to the
framing of scientific laws. It is important to establish exactly what is
meant by 'law' in this case. In common parlance, 'law' is taken to be something
which is imposed, a rule that is to be obeyed. But it would be wrong to assume
that a scientific law can dictate how things behave. The law simply describes
that behaviour, it does not control it (as Hume argued). If something behaves
differently, it is not to be blamed for going against a law of nature, it
is simply that either:
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there is an unknown factor that has influenced this particular
situation and therefore modified what was expected, or
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the law of nature is inadequately framed, and needs to be modified
in order to take this new situation into account.
A most influential thinker on this was
Karl Popper
(1902-1994), an Austrian philosopher from Vienna who moved to New Zealand
in 1937 and then to London in 1945, where he became Professor of Logic and
Scientific Method at the London School of Economics. He was a socialist,
and made significant contributions to political philosophy as well as the
philosophy of science.
In The Logic of Scientific Discovery (1934, translated in 1959) Popper
makes the crucial point that science seeks theories that are logically
self-consistent, and that can be falsified. He points out that a scientific
law goes beyond what can be experienced. We can never prove it to be absolutely
true, all we can do is try to prove it to be false, and accept it on a
provisional basis until such time as it is falsified.
This leads Popper to say that a scientific theory cannot be compatible with
all the logically possible evidence that could be considered. It must be
possible to falsify it. If a theory claims that it can never be falsified,
then it is not scientific.
In practice, of course, a theory is not automatically discarded as soon as
one possible piece of contrary evidence is produced. What happens is that
the scientist tries to reproduce that bit of contrary evidence, to show that
it is part of a significant pattern that the theory has not been able to
account for. Science also seeks out alternative theories that can include
all the positive evidence that has been found for the original one, but also
includes the new conflicting evidence.
An example
In Newtonian physics, light travels in a straight line. (This was confirmed
over the centuries, and was therefore corroborated as a theory.)
But modern astronomy has shown that, when near to a very powerful
gravitational field, light bends.
This does not mean that the Newtonian view was wrong, simply that
light does indeed travel in a straight line when in a uniform gravitational
field. The older theory is now included within a new one which can take into
account these exceptional circumstances. |
Where you have a choice of theories, Popper held that you should accept the
one that is better corroborated than the others, more testable, and entails
more true statements than the others. And that you should do this, even if
you know that the theory is false. The implication of this would seem to
be that science takes a pragmatic rather than an absolute approach to truth.
Since we cannot, anyway, have absolute certainty, we have to go for the most
useful way of understanding the world that we have to hand, even if its
limitations have already been revealed.
In other words
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I observe that Y follows X on a number of occasions.
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On the basis of this I put forward the hypothesis that X is
the cause of Y.
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I make further tests, and on each occasion Y follows X.
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I therefore formulate a scientific law to the effect that X
is the cause of Y, meaning that Y will always follow X.
But I can't know that for certain. I can't check out
every possible example of X.
Therefore it doesn't make the law any more secure to keep multiplying
the number of positive results that I get. To test out the law, what I really
need is a negative result. I need just
a single
example of an X which is not followed by a Y in order to show that the
law is wrong and needs modification or replacement. |
What difference do we make?
Karl Popper argued that science was not subjective, in the
sense of being the product of a single human mind, but neither was it literally
objective (i.e. a scientific law is not an external 'fact', but a way of
stating the relationship between facts as they appear to us). Rather, it
transcends the ideas of individuals, as does art, literature or maths. But
exactly what sort of difference do we make to our perception of the world?
The process of induction is based on the idea that it is possible to get
hard evidence which does not depend upon the person who observes it.Indeed,
from Francis Bacon onwards the theory has been that a scientist sets aside
all personal preferences in assessing data. Thus the resulting theory is
meant to apply to all people at all times. But can we observe nature without
influencing it by our act of observing it, and how much of what we think
of as evidence is contributed by our own minds? The sensations that we have
are not simply copies of external reality, they are the product of the way
in which we have encountered that reality: colour is a result of a combination
of light,surface texture and the operation of our eyes;space is perceived
as a result of our brain linking one thing to another;time is a matter of
remembering that some experiences have already taken place.Scientific theories
are therefore not based on independent facts,but are the product of our ways
of looking and thinking.
Kant argued that when we observe something, our mind has a contribution to
make to that experience. Space, time and causality are all imposed on experience
by the mind in order to make sense of it. Physics, since Einstein, has endorsed
this relevance of the observer for an understanding of what it observed.
As we saw earlier, neither space nor time is fixed, and movement is only
perceived in terms of the change in position of one body in relation to
another.
Example
I look out of the window of a stationary train at the train at the next
platform. Suddenly1 what I see starts to move. But is my train moving forward
or is the other train pulling away? Unless I feel a jolt, it will be a moment
before I can decide between the two -and I will only be able to do so by
looking beyond or away from the other train to some third object. |
Following Popper, and also following ideas considered in Chapter
1 in connection with epistemology in general, we see that what is perceived
may be understood to transcend the individual perceiver simply because that
perception is shared. Several people all witnessing the existence of a table
in the room will confirm my own perception. In the same way, scientific evidence,
repeated in various experiments, gives a transpersonal element of truth,
even if the object being studied, and the way in which it is described,
ultimately depend upon human perceptions. We do indeed make a difference,
but science can take account of those differences.
New evidence?
A theory which may be deemed inadequate on the basis of
lack of evidence, may find that subsequent evidence of a very different kind
can make it again a theory of choice. In this way, a theory survives when
it adapts to new situations yielding new evidence. Theories may have to adapt
in order to survive a kind of natural selection in the scientific world.
A particularly appropriate example of this may be
Charles
Darwin's theory of natural selection. Darwin published
The Origin
of Species in 1859. In it he put forward his theory that species
could gradually evolve through the selective passing of qualities to successive
generations by those members of a species who were most able to survive and
breed. This was not a moral theory, but an intuitive grasp of a process that
he considered the best explanation for the variety of species that he observed
and catalogued.
The basic facts are difficult to challenge. Those who survive into
adulthood do in fact breed. Those species that adapt to a particular environment
thrive there. Such evidence leads to a hypothesis which becomes the basis
for a theory which claims to explain changes that span millennia.
By thus following the inductive method, Darwin claimed to have discovered
the mechanism by which species evolve, and also an explanation of those features
of each species which seem most appropriate to its own survival. The inductive
method has therefore, so it seemed, replaced ideas of design (see p.130).
The debates that followed the publication of Darwin's theory were not simply
about his perceived challenge to religious ideas,
but about his interpretation of evidence. In particular, there did not seem
to be adequate fossil evidence for a gradual transition from one species
to another. And, of course, weighing such evidence was an essential feature
of the inductive method.
Comment
Perhaps the theory of natural selection represents a halfway house between
a strict inductive method of scientific argument and the sort of imaginative
leap from a limited experience to a more general theory.
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Darwin did gather a great deal of evidence, but the debates
that followed were sparked by the recognition that, if such a theory of evolution
was correct, then its implications were far beyond his areas of research.
If species are not fixed,then everything is subject to change.To accept such
an idea (with all its scientific, social, emotional and religious implications)
on the basis of limited evidence was to take a great risk.
The basis upon which a theory is examined may change over a period of time.
One of the major criticisms of Darwin's theory of evolution was the lack
of fossil evidence for the 'half-way' stages of change from what appeared
to be one fixed species to another. Since many of those who wish to challenge
Darwin's theory do so for religious reasons, their concern is with
origins,
and they therefore tend to look to the past.
In fact, further evidence for the general validity of Darwin's approach now
comes from the present. In a book entitled The Beak of the Finch (1994),
Jonathan Weiner describes a 20-year
study of
finches on one of the Galapagos Islands, showing, for example, that in
times of drought only those finches with the longest beaks could succeed
in getting the toughest seeds, and therefore survived to breed. At the same
time DNA studies of blood from various finches corresponded to their physical
abilities and characteristics.
More generally, evidence for survival of those best able to adapt to their
changing environment is seen all the time in terms of medicine and agriculture.
As soon as a pesticide appears to have brought a particular pest under control,
a new strain is found which is resistant to it. Equally, in medicine, new
strains of disease are appearing which are resistant to the available
antibiotics. What is happening is that those examples of a pest or a disease
which survive the onslaught of a pesticide or treatment, breed. The next
generation is, therefore, resistant. These examples show the flexibility
of nature: the present disease has been 'designed', not by some original
designer but in response to existing treatments. We see an evolution
of species and diseases over a space of a few years, mirroring the longer
term evolution over millennia.
There is no way that Darwin could have considered his theory from the standpoint
of genetic
mutation, or from the way in which viruses adapt and take on new forms,
but such new areas of evidence may be used to corroborate a previously held
theory, particularly where (as was the case with Darwin) the problem was
not so much that his theory had been falsified as that there was a perceived
lack of positive evidence.
Right, wrong or what?
The Newtonian world was at least predictable. A law of nature
could be regarded as a fixed piece of information about bow the world worked.
That has
now gone. We find that science can offer equally valid but different
ways of viewing the same phenomenon. There are no absolutes of space or time.
Quantum theory is seen to work (results can be predicted on the basis of
it) but without people understanding exactly why.
An example
Light can be understood in terms of particles or in terms of wave motions.
These are two utterly different ways of understanding the same thing, but
the fact that one is right does not mean that the other is wrong. |
As laws and theories become established within the scientific
community, they are used as a basis for further research, and are termed
'paradigms'. Occasionally there is a paradigm shift, which entails
the revision of much of science. In terms of cosmology, the move from an
Aristotelian (Ptolemaic) to a Newtonian world-view, and then the further
move from that to the view of Einstein, represents two shifts of paradigm.
Science offers a set of reasoned views about how the world has been seen
to work up to the present. Taken together, the laws of science that are
understood at any one time provide a structure within which scientists work,
a structure which guides, influences but does not dictate how scientific
research will progress. With hindsight we can see philosophers and scientists
boldly proclaiming the finality of their particular vision of the world just
as the scientific community is about to go through a 'paradigm shift' as
a result of which everything is going to be re-assessed.
An example
In 1899 Haeckel published The Riddle of the Universe. He argued that
everything, including thought, was the product of material world and was
controlled by its laws. Everything was absolutely controlled and determined.
Freedom was an illusion and religion a superstition. He was proposing scientific
materialism, popularising Darwin's theory of evolution, and sweeping away
all earlier philosophy which did not fit his material and scientific outlook.
What would Haeckel have made of relativity and quantum theory? |
T S Kuhn,
in his book The Structure of Scientific Revolutions (1962), described
these paradigms as the basic Gestalt (or world-view) within which science
at any one time interprets the evidence it has available. It is the paradigm
that largely dictates scientific progress, and observations are not free
from the influence of the paradigm. What makes Kuhn's theory particularly
controversial is that he claims that there are no independent data by which
to decide between competing paradigms (since all data are presented in terms
of either one paradigm or the other) and therefore there is no strictly logical
reason to change a paradigm. This implies a relativism in science, which
seemed to threaten the logical basic of the development of scientific theories,
as expounded by Karl Popper. The general implication of the work of Kuhn
and others is that, if a theory works well (in other words, if it gives good
predictive results), then it becomes a possible explanation: we cannot say
that it is the definitive or only one.
In other words
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Different theories can give an equally true explanation of
the same phenomenon.
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A scientific theory is a way of looking: a convenient way of
organising experience, but not necessarily the only one. It is provisional.
It is also part of an overall paradigm.
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Does that make any one scientific theory right, wrong or what?
This is a question for the philosophy of science: Can we say that something
is 'right' in a world of optional viewpoints?
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