The philosophy of science examines the methods used by science,
the ways in which hypotheses and laws are formulated from evidence, and the
grounds on which scientific claims can be justified.
Philosophy and science are not, in principle, opposed to one another, but
are in many ways parallel operations, for both seek to understand the nature
of the world and its structures. Whereas the individual sciences do so by
gathering data from within their particular spheres and formulating general
theories for understanding them, philosophy tends to concern itself with
the process of formulating those theories and establishing how they relate
together to form an overall view. We saw in Chapter 1 that metaphysics is
the task of understanding the basic structures of reality that lie behind
all the findings of individual sciences.
A major part of all philosophy is analysing the language people use and the
criteria of truth that they accept. While the individual sciences use 'first
order language' (speaking directly about physical, chemical or biological
observations), philosophy uses 'second order language' (examining what it
means to speak about those things). It does this by looking at what is said,
and whether or not the language used accurately reflects the reality that
it purports to describe.
Today, scientists tend to work in specialised fields - a particular branch
of physics, for example - because it is quite impossible for anyone to have
the sort of detailed knowledge of the current state of research in all the
various aspects of science. Scientists, mathematicians and philosophers may
therefore be seen today as working in different disciplines, even if each
is interested in and may benefit from the work of the others. It was not
always so, and physics was originally known as 'natural philosophy'. What
is more, some of the greatest names in philosophy were involved with mathematics
and science.
Aristotle examined and codified the various sciences, and did so within his
overall scheme of philosophy. Descartes, Leibniz, Pascal and Russell were
all mathematicians as well as philosophers. (Indeed, Russell and Whitehead
argued in Principia Mathematica (1910-1913) that mathematics was a
development of deductive logic - see p.77.) Bacon,
Locke and others were influenced by the rise of modern scientific method,
and were concerned to give it a sound philosophical basis. Kant wrote A
General Natural History and Theory of the Heavens in 1755 in which he
explored the possible origin of the solar system. Some philosophical movements
(for example, Logical Positivism, in the early years of the 20th century
- see p.66.) were influenced by science and the scientific method of establishing
evidence. Many of the philosophers that we considered in Chapter 1 can therefore
re-appear in considering science - largely because scientific knowledge
and its methods are such an important part of our general appreciation of
the scope and method of human knowledge.
In order to put these things into perspective, however, we shall take a brief
historical look at some of the philosophers who commented on science, or
were influenced by it.
An historical overview
Within Western thought there have been two major shifts in
the view of the world, and these have had an important influence on the way
in which philosophy and science have related to one another. We may therefore
divide Western philosophy of science into three general periods: early Greek
and medieval thought; the Newtonian world-view; 20th-century science (although
recognising that such division represents the simplification of a more complex
process of change).
Early Greek and medieval thought
In 529 CE the Emperor Justinian banned the teaching of philosophy in order
to further the interests of Christianity. Plato had already had a considerable
influence upon the development of Christian doctrines, and elements of his
thought - particularly the contrast between the ideal world of the forms
and the limited world of everyday experience - continued within theology.
The works of Aristotle were preserved first in Byzantium and then by the
Arabs, being rediscovered only in the 13th century, when the first translations
were made from Arabic into Latin.
It is only from the 13th century, therefore, with thinkers such as Thomas
Aquinas (1225-1274), Duns Scotus (1266-1308) and
William of Ockham (ci
285-1349), thai Greek thought began to be explored again in a systematic
way. From that time, philosophy is very much a development , or reaction
to, the work of the Greeks. It is only with Descartes (see p. 157) that it
starts again from first principles, and this coincided with the move into
the second phase of science.
Aristotle set out the different branches of science, and divided up living
things into their various species and genera - a process of classification
which became a major feature of science. He had a theory of knowledge based
on sensations which depended on repetition:
sensations repeat themselves
® leading to perception
perceptions repeat themselves ®
leading to experience
experiences repeat themselves ®
leading to knowledge |
Therefore we find that knowledge is something that develops
out of our structured perception and experience of the material that comes
to us from our senses - an important feature of the philosophy of science.
He also established ideas of space, time and causality, including the idea
of the prime mover (which became the basis of the cosmological
argument for the existence of God - see p.127).
He set out the four 'causes' (see p.30), thus distinguishing between matter,
the form it took on, the agent of change and the final purpose or goal for
which it was designed. He considered a thing's power to be its potential.
Everything had a potential and a resting place: fire rises up naturally,
whereas heavy objects fall. Changes, for Aristotle, are not related to general
forces like gravity (which belong
to the later Newtonian scheme), but to the fact that individual things, by
their very nature, have a goal.
Let us look at a few examples of the influence of Plato and Aristotle. For
Plato, the unseen 'forms' were more real than the individual things that
could be known through the senses. This way of thinking (backed by religion)
led to the idea that reason and the concepts of perfection could determine
what existed, and that any observations which appeared to contradict this
must automatically be wrong.
Cosmology and astronomy give examples of this: Copernicus (1473-1543) and
later Galileo (1564-1642) were to offer a view of the universe in which the
earth revolved around the sun, rather than vice versa. Their view was opposed
by those whose idea of the universe came from Ptolemy and in which the earth
was surrounded by glassy spheres - perfect shapes, conveying the sun, moon
and planets in perfect circular motion. Their work was challenged (and Galileo
condemned) not because their observations were found to be at fault, but
because they had trusted - their observations, rather than deciding beforehand
what should be the case. Kepler (1571-1630) concluded that the orbit of Mars
was elliptical, whereas all heavenly motion was thought to be perfect, and
therefore circular.
These astronomers were struggling against a background of religious
authority which gave Greek notions of perfection priority over observations
and experimental evidence. In other words, the earlier medieval system of
thought was deductive - it deduced what should happen from its ideas,
in contrast to the later inductive method of getting to a theory from
observations.
Along with the tendency to look for theory and perfection rather than accept
the results of observation, there was another, stemming from Aristotle. Following
his idea of the final cause, everything was thought to be designed for a
particular purpose. If something falls to the ground, it seeks its natural
purpose and place in doing so. So, in a religious context, it was possible
to say that something happened because it was God's will for it, or because
it was designed for that purpose. There was no need to look for a scientific
principle or law which would apply to everything without distinction.
The Newtonian world view
The rise of modern science would not have been possible without
the renewed sense of the value of human reason and the ability to challenge
established ideas and religious dogma, which developed as a result of the
Renaissance and the Reformation. But what was equally influential was the
way in which information was gathered and sorted, and theories formed on
the basis of it. Central to this process was the method of induction, and
this was set out very clearly (and in a way that continues to be relevant)
by Francis Bacon. Bacon (1561-1626) rejected Aristotle's idea of final causes,
and insisted that knowledge should he based on a process of induction, which,
as we shall see later, is the systematic method of coming to general conclusions
on the basis of evidence about individual instances that have been observed.
He warned about 'idols': those things that tend to lead a person astray.
They included:
-
the desire to accept that which confirms what we already
believe;
-
distortions resulting from our habitual ways of thinking;
-
muddles that come through our use of language
(e.g. using the same word for different things, and then assuming that
they must be one and the same);
-
believing things out of allegiance to a particular school of
thought.
Bacon also pointed out that, in gathering evidence, one should
not just seek those examples that would confirm a particular theory,
but should actively seek out and accept the force of contrary examples.
After centuries of using evidence to confirm what was already known by dogma
or reason, this was quite revolutionary.
The general view of the world which came about as a result of the rise of
science is usually linked with the name of Isaac
Newton (1642-1727). In the Newtonian world-view, observation and experiment
yield knowledge of the laws which govern the world. In it, space and time
were fixed, forming a framework within which everything takes place. Objects
were seen to move and be moved through the operation of physical laws of
motion, so that was seen as a machine, the workings of which could become
known through careful observation. Interlocking forces kept matter in motion,
and everything was
predictable. Not everything might be known at this moment, but there
was no doubt that everything would be understood eventually, using the
established scientific method.
Put crudely, the world was largely seen as a collection of particles of matter
in motion - hitting one another, like billiard balls on a table, and behaving
in a predictable way. It was thought that science would eventually give an
unchallengeable explanation for everything, and that it would form the basis
for technology that would give humankind increasing control over the environment,
and the ability to do things as yet unimagined. Science became cumulative
- gradually expanding into previously unknown areas; building upon the secure
foundations of established physical laws.
Newton was a religious
believer; he thought that the laws by which the universe operated had
been established by God. But his god was an external creator who, once
the universe had been set in motion, could retire, leaving it to continue
to function according to its fixed laws. This view freed science from the
need to take God into account: it could simply examine the laws of nature,
and base its theories on observation rather than religious dogma.
With the coming of the Newtonian world-view, the function of philosophy changed.
Rather than initiating theories about cosmology, the task of philosophy was
to examine and comment on the methods and results of scientific method,
establishing its limits. It also pointed out, through Kant, that the laws
of nature (indeed, space, time and causality - the very bases of Newtonian
science) were not to be found 'out there' in the world of independent objects,
but were contributed by the mind.
Hume pointed out that scientific laws were not true universal statements,
but only summaries of what had been experienced so far. The very method used
- gathering data and drawing general conclusions from it - yielded higher
and higher degrees of probability, but there was no way of moving from this
to absolute certainty.
Some aspects of philosophy related to this phase of science
have already been examined (in Chapter 1). Hume's empiricism, for example,
fits perfectly with the scientific impetus. At the beginning of the 19th
century William
Paley's argument in favour of a designer for
the universe (see p.130) reflects the domination of his world-view by the
paradigm of the machine - a designer (God) is proposed in order to account
for the signs of design in creation.
But not all philosophers of this second scientific era supported Newton's
fixed mechanical universe. Bishop Berkeley criticised Newton's idea that
space and time are fixed. For Berkeley everything (including matter and
extension) is a matter of sensation, of human experience. Thus everything
is relative to the person who experiences it, and there is no logical way
to move from the relativity of our experience to some external absolute.
In his own way, Berkeley anticipates the arrival of the third era for science
and philosophy.
20th-century science
For most thinkers prior to the 20th century, it was inconceivable that space
and time were not fixed: a necessary framework within which everything else
could take place.
Einstein's
theories
of relativity were to change all that. The first, in 1905, was the theory
of Special Relativity, best known in the form of the equation
E=mc2. This showed that mass and energy are equivalent, and that
(since energy was equal to mass multiplied by the speed of light squared)
a very small amount of matter could be converted into a very large amount
of energy. This, of course, is now best known for its rather drastic practical
consequences in the development of nuclear weapons.
Einstein published the second theory, that of General
Relativity, in 1916. It made the revolutionary claim that time, space,
matter and energy were all related to one another. For example, space and
time can be compressed by a strong gravitational field. There are no fixed
points. The way in which things relate to one another depends upon the point
from which they are being observed.
An example
Imagine you are looking out through space. You see two stars, which, although
they may appear to you to be the same distance away, are in fact many light
years apart. Suppose you see a change in one of those stars, followed by
a change in the other. You might reasonably claim that one happened first,
because, from your perspective, they occurred in a time sequence which, on
earth, would amount to one coming first and the other second. From the standpoint
of someone placed equidistant between the two, however, the two events might
appear simultaneous.
But imagine that you are transported to a star that is beyond the second
of the stars you have been observing. In this case you might see the second
change first and the first change second. Clearly, the reason for this is
that the time at which something 'happens' (or, strictly speaking, appears
to happen) is related to the distance it is from you, because events only
come to be observed after the light from them had travelled across space.
It is therefore impossible to say which event will be experienced as coming
first; the sequence depends on the location of the observer. Of course, you
could calculate which 'actually' happened first, from your perspective, if
you knew the distances to the two stars. You could then calculate the extra
length of time it took light to travel to you from the further star, and
deduct that from the time difference between the two experienced events.
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Modern physics and modern cosmology therefore offer a strange view of space
and time, a view that is in contrast to that of the Newton. We are told that
whole universe emerged (at the 'Big Bang')
from a space-time singularity - a point at
which all matter in the present universe was concentrated into a very small
point. Unlike an ordinary explosion, in which matter is propelled outwards
through space, space and time were created at that moment, and space expanded
as did the universe. If space could be represented by a grid of lines drawn
on a balloon, then as the balloon is blown up, the grid itself expands, the
balloon doesn't simply get more lines drawn on it.
The reason Newton's physics worked on the basis of fixed space and time was
that he only considered a very small section of the universe, and within
that section, his laws do indeed hold true. Space and time are seen as linked
in a single four-dimensional space-time
continuum, and there is no fixed point from which to observe anything,for
observer and observed are both in a process of change,moving through both
time and space. Alongside relativity came quantum
mechanics, which raised questions about whether events
at the sub-atomic
level could be predicted, and what it means to say that one thing causes
another. Matter was no longer thought to be composed of solid atoms, but
the atom itself was divided into many constituent
particles, held together by forces. In the sub-atomic world ,particles did
not obey fixed rules. Their individual movements, while statistically
predictable,were uncertain. Energy was seen to operate by the interchange
or 'quanta', rather than by a single continuous flow. What had once been
solid matter obeying fixed mechanical laws, could now be thought of as bundles
of events open to a number of different interpretations depending on the
viewpoint of the observer. Quantum mechanics is notoriously difficult
to understand. The general view of it is that it works, so there must
be something right about it, even if we don't understand it as a theory.
What is certain is that quantum mechanics, however little understood, when
combined with the theories of relativity, rendered the
old Newtonian certainties obsolete. Newton's
laws of physics might still apply, but only within very limited parameters.
Once you stray into the microscopic area of the sub-atomic, or the macroscopic
world of cosmic structures, the situation is quite different.
A similar revolution has taken place within the understanding of living things.
Through the discovery of DNA, the world
of biology is linked to that of chemistry and of physics, since the instructions
within the DNA molecule are able to determine the form of the living being.
In the 20th century, therefore, philosophy engaged with a scientific world
and set of ideas that had changed enormously from the mechanical and predictable
world of Newton. In particular, science now offers a variety of ways of picturing
the world, and cosmology - dominated first by religious belief and Aristotle,
then by astronomy - is now very much in the hands of mathematicians.
The world as a whole is not something that can be observed, but something
whose structure can be explored by calculation.
During much of the first half of the 20th century, philosophy (at least in
the USA and Britain) came to be dominated by the quest for meaning and the
analysis of language. It no longer saw its role as providing an overview
of the universe - that was left to the individual scientific disciplines.
Rather, it adopted a supportive role, checking on the methods used by science,
the logic by which results were produced from observations, and the way in
which theories could be confirmed or discredited.
In other words
-
Until the 16th century Greek concepts, backed by religious
authority, determined the general view of the world. Evidence was required
to fit the overall scheme.
-
In Newtonian physics, matter exists within a fixed structure
of space and time, and obeys laws that can be discovered by 'induction' based
on observation.
-
The modern world-view sees space and time as related to one
another, and events as interpreted in the light of the observer's own position
and methods of observation.
In the first phase, philosophy seemed to determine content,
in the second it offered a critique of method, and in the third it offers
a clarification of concepts. |
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