Samir Okasha - Philosophy of Science - Chapt 1 'What Is Science' PDF
Samir Okasha - Philosophy of Science - Chapt 1 'What Is Science' PDF
Samir Okasha - Philosophy of Science - Chapt 1 'What Is Science' PDF
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vision ofthe second half of the 17th century; to some extent it is still
with us today. Versions ofthe mechanical philosophy were espoused
, by figures such as Huygens, Gassendi, Hooke, Boyle, and others; its
. widespread acceptance marked the final downfall of the
Aristotelian world-view.
Newtonian physics provided the framework for science for the next
200 years or so, quickly replacing Cartesian physics. Scientific
2. Sketch ofGalileo's mythical experiment on the velocity of objects
dropped from the Leaning Tower of Pisa. confidence grew rapidly in this period, due largely to the success of
J
Newton's theory, which was widely believed to have revealed the a brief description of modern science's origins would be incomplete
true workings of nature, and to be capable of explaining everything, ifit omitted all mention ofthe non-physical sciences.
in principle at least. Detailed attempts were made to extend the
Newtonian mode of explanation to more and more phenomena. In biology, the event that stands out is Charles Darwin's discovery
The 18th and 19th centuries both saw notable scientific advances, of the theory of evolution by natural selection, published in The
particularly in the study of chemistry, optics, energy, Origin ojSpecies in 1859. Until then it was widely believed that
thermodynamics, and electromagnetism. But for the most part, the different species had been separately created by God, as the
these developments were regarded as falling within a broadly Book of Genesis teaches. But Darwin argued that contemporary
Newtonian conception of the universe. Scientists accepted species have actually evolved from ancestral ones, through a
Newton's conception as essentially correct; all that remained to be process known as natural selection. Natural selection occurs when
done was to fill in the details. some organisms leave more offspring than others, depending on
their physical characteristics; if these characteristics are then
Confidence in the Newtonian picture was shattered in the early inherited by their offspring, over time the population will become
years of the 20th century, thanks to two revolutionary new better and better adapted to the environment. Simple though this
developments in physics: relativity theory and quantum process is, over a large number of generations it can cause one
~ mechanics. Relativity theory, discovered by Einstein, showed that species to evolve into a wholly new one, Darwin argued. So
~ Newtonian mechanics does not give the right results when persuasive was the evidence Darwin adduced for his theory that by
'Ci applied to very massive objects, or objects moving at very high the start of the 20th century it was accepted as scientific
~
_!... velocities. Quantum mechanics, conversely, shows that the orthodoxy, despite considerable theological opposition (Figure 3).
Newtonian theory does not work when applied on a very small Subsequent work has provided striking confirmation of Darwin's
if
scale, to subatomic particles. Both relativity theory and quantum theory, which forms the centrepiece of the modern biological
mechanics, especially the latter, are very strange and radical 't. world-view.
theories, making claims about the nature of reality that many
people find hard to accept or even understand. Their emergence The 20th century witnessed another revolution in biology that is
caused considerable conceptual upheaval in physics, which not yet complete: the emergence of molecular biology, in particular
continues to this day. molecular genetics. In 1953 Watson and Crick discovered the
structure of DNA, the hereditary material that makes up the genes
So far our brief account of the history of science has focused mainly in the cells ofliving creatures (Figure 4). Watson and Crick's
on physics. This is no accident, as physics is both historically very discovery explained how genetic information can be copied from
important and in a sense the most fundamental of all scientific one cell to another, and thus passed down from parent to offspring,
disciplines. For the objects that other sciences study are themselves thereby explaining why offspring tend to resemble their parents.
made up of physical entities. Consider botany, for example. Their discovery opened up an exciting new area of biological
Botanists study plants, which are ultimately composed of molecules research. In the 50 years since Watson and Crick's work, molecular
and atoms, which are physical particles. So botany is obviously less biology has grown fast, transforming our understanding ofheredity
fundamental than physics - though that is not to say it is any less and of how genes build organisms. The recent attempt to provide a
important. This is a point we shall return to in Chapter 3. But even molecular-level description of the complete set of genes in a human
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MR. BlmGB TO ':$!I RBSClUlI. 4. James Watson and Francis Crick with the famous 'double helix'-
Man wutatOeIainl ,:m,.Pedi~
THE DEFRAUDED GOIULLA.u'.I'ha.t u. their molecular model of the structure of DNA, discovered in 1953.
of my Descendants."
Mr. BERGH. "Now, Mr. DARWIIl1,howtouldyott insult him so?"
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What is philosophy of science? said, it must be admitted that many scientists today take little
interest in philosophy of science, and know little about it. While this
The principal task of philosophy of science is to analyse the is unfortunate, it is not an indication that philosophical issues are
methods of enquiry used in the various sciences. You may wonder no longer relevant. Rather, it is a consequence of the increasingly
why this task should fall to philosophers, rather than to the specialized nature of science, and of the polarization between the
scientists themselves. This is a good question. Part of the answer is sciences and the humanities that characterizes the modern
that looking at science from a philosophical perspective allows us to education system.
probe deeper - to uncover assumptions that are implicit in scientific
practice, but which scientists do not explicitly discuss. To illustrate, You may still be wondering exactly what philosophy of science is all
consider scientific experimentation. Suppose a scientist does an about. For to say that it 'studies the methods of science', as we did
experiment and gets a particular result. He repeats the experiment above, is not really to say very much. Rather than try to provide a
a few times and keeps getting the same result. After that he will more informative definition, we will proceed straight to consider a
probably stop, confident that were he to keep repeating the typical problem in the philosophy of science.
experiment, under exactly the same conditions, he would continue
to get the same result. This assumption may seem obvious, but as
Science and pseudo-science
~ philosophers we want to question it. H'hy assume that future
~ repetitions of the experiment will yield the same result? How do we Recall the question with which we began: what is science? Karl ~
Popper, an influential 20th-century philosopher of science, thought ;;'
I_
'Q know this is true? The scientist is unlikely to spend too much time
puzzling over these somewhat curious questions: he probably has
better things to do. They are quintessentially philosophical
that the fundamental feature of a scientific theory is that it should
be falsifiable. To call a theory falsifiable is not to say that it is false.
~
~
if questions, to which we return in the next chapter. Rather, it means that the theory makes some definite predictions
that are capable of being tested against experience. If these
So part of the job of philosophy of science is to question predictions turn out to be wrong, then the theory has been falsified,
assumptions that scientists take for granted. But it would be wrong or disproved. So a falsifiable theory is one that we might discover to
to imply that scientists never discuss philosophical issues be false - it is not compatible with every possible course of
themselves. Indeed, historically, many scientists have played an experience. Popper thought that some supposedly scientific theories
important role in the development of philosophy of science. did not satisfY this condition and thus did not deserve to be called
Descartes, Newton, and Einstein are prominent examples. Each science at all; rather they were merely pseudo-science.
was deeply interested in philosophical questions about how science
should proceed, what methods of enquiry it should use, how much Freud's psychoanalytic theory was one of Popper's favourite
confidence we should place in those methods, whether there are examples of pseudo-science. According to Popper, Freud's theory
limits to scientific knowledge, and so on. As we shall see, these could be reconciled with any empirical findings whatsoever.
questions still lie at the heart of contemporary philosophy of Whatever a patient's behaviour, Freudians could find an
science. So the issues that interest philosophers of science are not explanation of it in terms of their theory - they would never admit
'merely philosophical'; on the contrary, they have engaged the that their theory was wrong. Popper illustrated his point with the
attention of some of the greatest scientists of all. That having been following example. Imagine a man who pushes a child into a river
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with the intention of murdering him, and another man who deflected by the sun, this would have showed that Einstein was
sacrifices his life in order to save the child. Freudians can explain wrong. So Einstein's theory satisfies the criterion offalsifiability.
both men's behaviour with equal ease: the first was repressed, and
the second had achieved sublimation. Popper argued that through Popper's attempt to demarcate science from pseudo-science is
the use of such concepts as repression, sublimation, and intuitively quite plausible. There is certainly something fishy about
unconscious desires, Freud's theory could be rendered compatible a theory that can be made to fit any empirical data whatsoever. But
with any clinical data whatever; it was thus unfalsifiable. some philosophers regard Popper's criterion as overly simplistic.
Popper criticized Freudians and Marxists for explaining away any
The same was true of Marx's theory of history, Popper maintained. data that appeared to conflict with their theories, rather than
Marx claimed that in industrialized societies around the world, accepting that the theories had been refuted. This certainly looks
capitalism would give way to socialism and ultimately to like a suspicious procedure. However, there is some evidence that
communism. But when this didn't happen, instead of admitting this very procedure is routinely used by 'respectable' scientists -
that Marx's theory was wrong, Marxists would invent an ad hoc whom Popper would not want to accuse of engaging in pseudo-
explanation for why what happened was actually perfectly science - and has led to important scientific discoveries.
consistent with their theory. For example, they might say that the
.. inevitable progress to communism had been temporarily slowed Another astronomical example can illustrate this. Newton's
I by the rise of the welfare state, which 'softened' the proletariat
'0 and weakened their revolutionary zeal. In this sort of way, Marx's
gravitational theory, which we encountered earlier, made
predictions about the paths the planets should follow as they orbit
f
~
~
... theory could be made compatible with any possible course of the sun. For the most part, these predictions were borne out by ~
_a events, just like Freud's. Therefore neither theory qualifies as observation. However, the observed orbit of Uranus consistently ~
if genuinely scientific, according to Popper's criterion. differed from what Newton's theory predicted. This puzzle was
solved in 1846 by two scientists, Adams in England and Leverrier
Popper contrasted Freud's and Marx's theories with Einstein's~' .... in France, working independently. They suggested that there was
theory of gravitation, also known as general relativity. Unlike another planet, as yet undiscovered, exerting an additional
Freud's and Marx's theories, Einstein's theory made a very definite gravitational force on Uranus. Adams and Leverrier were able to
prediction: that light rays from distant stars would be deflected by calculate the mass and position that this planet would have to have,
the gravitational field of the sun. Normally this effect would be if its gravitational pull was indeed responsible for Uranus' strange
impossible to observe - except during a solar eclipse. In 1919 the behaviour. Shortly afterwards the planet Neptune was discovered,
English astrophysicist Sir Arthur Eddington organized two almost exactly where Adams and Leverrier had predicted.
expeditions to observe the solar eclipse of that year, one to Brazil
and one to the island of Principe off the Atlantic coast ofAfrica, Now clearly we should not criticize Adams' and Leverrier's
with the aim of testing Einstein's prediction. The expeditionsfuund" behaviour as 'unscientific' - after all, it led to the discovery of a new
that starlight was indeed deflected by the sun, by almost exactly the planet. But they did precisely what Popper criticized the Marxists
amount Einstein had predicted. Popper was very impressed by this. for doing. They began with a theory - Newton's theory of gravity-
Einstein's theory had made a definite, precise prediction, which was which made an incorrect prediction about Uranus' orbit. Rather
confirmed by observations. Had it turned out that starlight was not than concluding that Newton's theory must be wrong, they stuck by
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the theory and attempted to explain away the conflicting
observations by postulating a new planet. Similarly, when
capitalism showed no signs ofgiving way to communism, Marxists
did not conclude that Marx's theory must be wrong, but stuck by the
theory and tried to explain away the conflicting observations in
other ways. So surely it is unfair to accuse Marxists of engaging in
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not. The philosopher Ludwig Wittgenstein argued that there is no
fixed set of features that define what it is to be a 'game'. Rather,
there is a loose cluster offeatures most of which are possessed by
most games. But any particular game may lack any ofthe features in
the cluster and still be a game. The same may be true of science. If
so, a simple criterion for demarcating science from pseudo-science
pseudo-science if we al10w that what Adams and Leverrier did is unlikely to be found.
counted as good, indeed exemplary, science?
I_
'l5 some observations - finding a theory that fits al1 the data perfectly is
extremely difficult. Obviously if a theory persistently conflicts with
more and more data, and no plausible ways of explaining away the
f conflict are found, it wil1 eventual1y have to be rejected. But little
progress would be made if scientists simply abandoned their '''r
theories at the first sign of trouble.
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