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The philosophy of science is the branch of philosophy which
studies the philosophical foundations, presumptions and implications of science both
of the natural sciences like physics and biology and the social sciences such as psychology and
economics. In this respect, the philosophy of science is closely related to
epistemology and ontology. It
seeks to explain such things as: the nature of scientific statements and concepts; the way in which they are produced; how
science explains, predicts and harnesses nature; the means for determining the validity of information; the formulation and use
of the scientific method; the types of reasoning used to arrive at conclusions; and the implications of scientific methods and
models for the larger society, and for the sciences themselves.
All sciences have an underlying philosophy regardless of claims to the contrary:
- There is no such thing as philosophy-free science; there is only science whose philosophical baggage is taken on board
without examination. —Daniel Dennett
This article is not exhaustive; it covers only those topics that are seen as central by all of the major philosophies of
science. As with the philosophy of mathematics,
there tend to be 'schools' of scientific thought, each of which adheres to its own principles.
Nature of scientific statements and concepts
As with the philosophy of mathematics and
central to the philosophy of science, there are (sometimes competing) ideologies
about the nature of scientific concepts.
Empiricism
One of the most central principles in the philosophy of science is that of empiricism, or dependence on evidence. Empiricism is the world
view that knowledge derives from experience of the world, in contrast to Continental rationalism which holds that knowledge derives from ideas. In this sense, scientific
statements are subject to and derived from our experiences or observations. Scientific theories are developed and tested through
experiments and observations. They are used to gather information through our senses, via empirical methods that many humans are capable of experiencing. Once reproduced widely enough by
many scientists, this information counts as evidence, upon which the scientific community bases its explanations of how things work.
Given enough reliable evidence, one can then use the principles of reason and logic (and other quasi-empirical methods
which complement the strictly empirical structure of experiment but which lead back to our sense of truth and invoke key conceptual metaphors) to work these explanations into a coherent,
self-consistent structure. The degree to which one can trust such methods is a major concern of the philosophy of science. Modern
definitions of reason and logic certainly have not been applied through the entire history of the scientific method, but results achieved by those earlier methods are
still valid, and are very rarely invalidated. This suggests that our unchanged conceptual metaphors (such as the ideas of similarity and sufficiency that drive counting and
measuring) may be more deeply rooted than any of our explanations of our thinking processes as humans, and as scientists.
Observations involve perception, and so are
themselves cognitive acts. That is, observations are themselves embedded in our understanding of the way in which the world
works; as this understanding changes, the observations themselves may apparently change.
Scientists attempt to use induction, deduction and quasi-empirical
methods, and invoke key conceptual metaphors to work
observations into a coherent, self-consistent structure.
Scientific realism
Scientific realism, also known as naive realism, is
the world view that the universe really is as explained by scientific statements. Realists hold that things like electrons and
magnetic fields actually exist. It is naïve in the sense of taking scientific models at face value, and is the view that most
scientists adopt.
Instrumentalism
In contrast to realism, instrumentalism holds that our
perceptions, scientific ideas and theories do not necessarily reflect the real world accurately, but are useful instruments to
explain, predict and control our experiences. To an instrumentalist, electrons and magnetic fields are convenient ideas that may
or may not actually exist. For instrumentalists, empirical method is used to do no more than show that theories are consistent
with observations. Instrumentalism is derived in part from John Dewey's
pragmatism.
Social Constructivism
Some historians, philosophers, and sociologists of science believe that scientific theories are shaped by their social and
political context. This approach is usually known as social
constructivism. Social constructivism is in one sense an extension of instrumentalism that incorporates the social aspects of
science. In its strongest form, it sees science as merely a discourse between scientists, with objective fact playing a small
role if any. A weaker form of the constructivist position might hold that social factors play a large role in the acceptance of
new scientific theories.
On the stronger account, the existence of Mars the planet is irrelevant, since all we really have are the observations,
theories and myths, which are all themselves constructed by social interaction. On this account, scientific statements are about
each other, and an empirical test is no more than checking the consistency between different sets of social constructed theories.
It becomes difficult, then, to explain how science differs from any other discipline; equally, however, it becomes difficult to
give an account of the extraordinary success of science in producing usable technology.
On the weaker account, Mars the planet might be said to have a real existence, separate and distinct from our observations,
theories and myths about it. Although theories and observations are socially constructed, part of the construction process
involves ensuring a correspondence of some sort with this reality. On this account, scientific statements 'are' about the real
world. The crucial issue for this account is explaining this correspondence. What justification is there for claiming that photos
from the latest probe are in some sense more real than the Roman myths about Mars? It is important, therefore, for Social
Constructivists to consider how scientific statements are justified.
Reductionism
Reductionism in science can have several different
senses. Essentially, it refers to the limits of the process of breaking up phenomena or processes into smaller and smaller parts
and assuming that the whole can be understood in this way.
A high degree of such reduction is essential to science itself, else it would be impossible to determine significant versus
not significant measurements, differences between apparatus and of experiments, etc.. What is more, it would be impossible to
rely on mathematics if one refused to reduce phenomena to numbers.
One type of reductionism is the belief that all fields of study are ultimately amenable to scientific explanation. Perhaps an
historical event might be explained in sociological and psychological terms, which in turn might be reduced to physiology and
ultimately to chemistry and physics. This might be seen as implying that the historical event was 'nothing but' the physical
event, denying the existence of emergent phenomena.
Reductionism might also be seen as a threat to free will.
Such objections to reductionism are justified against what Daniel
Dennett calls greedy reductionism, which he
claims is just 'bad science', seeking to find explanations which are
appealing or eloquent, rather than those that are of use in predicting natural phenomena.
Arguments made against greedy reductionism through reference to emergent
phenomena rely upon the fact that self-referential systems can be said to contain more information than can be described through individual analysis of their component parts. Examples include
systems that contain strange loops, fractal organisation and strange attractors in
phase space. Analysis of such systems is necessarily information-destructive
because the observer must select a sample of the system that can be at best partially representative. Information theory can be used to calculate the magnitude of
information loss and is one of the techniques applied by Chaos theory.
It is hard to separate the issues involved with objections to falsifiability or misuse of Occam's Razor, from those which
arise due to over-reduction of a complex set of phenomena. All such errors of method or choice of theories could be said to
actually be errors of greedy reduction.
The Justification of Scientific Statements
The most powerful statements in science are those with the widest applicability. Newton’s Third Law - "for every action
there is an opposite and equal reaction" - is a powerful statement because it applies to every action, anywhere, and at any
time.
But it is not possible for scientists to have tested every incidence of an action, and found a reaction. How is it, then, that
they can assert that the Third Law is in some sense true? They have, of course, tested many, many actions, and in each one have
been able to find the corresponding reaction. But can we be sure that the next time we test the Third Law, it will be found to
hold true?
Induction
One solution to this problem is to rely on the notion of induction. Inductive
reasoning maintains that if a situation holds in all observed cases, then the situation holds in all such cases. So, after
completing a series of experiments that support the Third Law, one is justified in maintaining that the Law holds in all
cases.
Explaining why induction is true has been somewhat problematic. One cannot use deduction, the usual process of moving
logically from premise to conclusion, because there is simply no syllogism that will allow such a move. No matter how many times
17th Century biologists observed white swans, and in how many different locations, there is
no deductive path that can lead them to the conclusion that all swans are white. This is just as well, since, as it turned out,
that conclusion would have been wrong. Similarly, it is at least possible that an observation will be done tomorrow that shows an
occasion in which an action is not accompanied by a reaction; the same is true of any scientific law.
One answer has been to conceive of a different form of rational argument, one that does not relying on deduction. Whereas
deduction allows one to formulate a specific truth from a general truth (all crows are black; this is crow; therefore this is
black), induction somehow allows one to formulate a general truth from some series of specific observations (this is a crow and
it is black; that is a crow and it is black; therefore all crows are black).
The problem of induction is one of considerable debate
and moment in the philosophy of science: is induction indeed justified, and if so, how?
Falsifiability
Another way to use logic to justify scientific statements, first formally discussed by Karl Popper, but now increasingly challenged, is falsifiability. This principle states that in order to be useful (or even scientific at all), a scientific
statement ('fact', theory, 'law', principle, etc) must be falsifiable, i.e. able to be proven wrong. Without
this property, it would be difficult (if not impossible) to test a scientific statement against the evidence. Falsification's aim
is to re-introduce deductive reasoning into the debate. It is not possible to deduce a general statement from a series of
specific ones, but it is possible for one specific statement to prove that a general statement is false. Finding a black swan might be sufficient to show that the general statement 'all swans are white'
is false.
Falsifiability neatly avoids the problem of induction, because it does not make use of inductive reasoning. However, it
introduces its own difficulties. When an apparent falsification occurs, it is always possible to introduce an addition to a
theory that will render it unfalsified. So, for instance, ornithologists might have simply argued that the large black bird found
in Australia was not a member of the genus Cygnus, but of some other, or perhaps some new, genus.
Critiques of this principle tend to follow one of two lines of argument: First, that theories are often accepted and built
upon as a result of their eloquence and elegance, e.g. mathematical simplicity, and that experimental evidence rarely 'falsifies'
but rather limits the application of such theories. These arguments tend to focus on the weaknesses of the logical law of the excluded middle, i.e. 'no gray areas', on
which the principle of falsifiability depends. Second, that many scientific theories are simply not so falsifiable, e.g. those in
the social sciences which are still called 'sciences', and very abstract models, e.g. string theory, Standard model in particle physics which can only be empirically tested by very expensive
tests and specialized apparatus, and so are amenable to a great deal of cultural pressure and groupthink all pushing the scientists to agree, and not to test the central tenets of theory, if such tests are
feasible at all. These arguments tend to focus on the trust of the general public in the scientific community and its works, and
the degree to which falsifiability actually drives what is called 'science' in the academies, research labs, textbooks, and
governments.
Coherentism
Induction and Falsification both attempt to justify scientific statements by reference to other specific scientific
statements. Both must avoid the problem of the
criterion, in which any justification must in turn be justified, resulting in an infinite regress. The regress argument has been used to justify one way out of the infinite
regress, foundationalism. Foundationalism claims that there are some
basic statements that do not require justification. Both induction and falsification are forms of foundationalism in that they
rely on basic statements that derive directly from observations.
The way in which basic statements are derived from observation complicates the problem. Observation is a cognitive act; that
is, it relies on our existing understanding – our set of beliefs. An observation of a transit of Venus requires a huge range of auxiliary beliefs, such as those that describe the optics
of telescopes, the mechanics of the telescope mount, and an understanding of celestial mechanics. Prima facie, the observation
does not appear to be 'basic'.
Coherentism offers an alternative by claiming that statements can be
justified by their being a part of a coherent system. In the case of science, the system is usually taken to be the complete set
of beliefs of an individual or of the community of scientists. W. V. Quine
argued for a Coherentist approach to science. An observation of a transit of Venus is justified by its being coherent with our
beliefs about optics, telescope mounts and celestial mechanics. Where this observation is at odds with one of these auxiliary
beliefs, an adjustment in the system will be required to remove the contradiction.
Occam's Razor
Occam's Razor is another notable touchstone in the philosophy of
science. William of Occam (or Ockhegm or several other spellings)
suggested that the simplest account which 'explains' the phenomenon is to be
preferred. He did not suggest that it would be true, or even more likely to be true, though 'simpler' has very often turned out
to be more likely to be right (in hindsight) than 'more complex'.
Occam's Razor has usually been used just as a rule of thumb for
choosing between equally 'explanatory' hypotheses (ie, theories) about one or
more observed phenomena. However, it is rare that two theories explain equally, so its use has been limited. There are
now mathematical approaches based on information theory that
balance explanatory power with simplicity. One such is minimum message length inference.
Occam's Razor is often abused and cited where it is inapplicable. It does not say that the simplest account is to be preferred
regardless of its capacity to explain outliers, exceptions, or other phenomena in question. The principle of falsifiability
requires that any exception that can be reliably reproduced should invalidate the simplest theory, and that the next-simplest
account which can actually incorporate the exception as part of the theory should then be preferred to the first.
Social accountability
Scientific Infallibility
A critical question in science is, to what degree the current body of scientific knowledge can be taken as an indicator of
what is actually 'true' about the physical world in which we live. The acceptance of knowledge as if it were absolutely 'true'
and unquestionable (in the sense of theology or ideology) is is called scientism, and most scientists agree it is
a bad idea..
However, it is common for members of the public to have the opposite view of science — many lay people believe that
scientists are making claims of infallibility. Science tends to serve as the process of consensus decision making by which people of varying
moral and ethical views come to agree on 'what is real'. Therefore, it becomes difficult in a secular and technological society,
without any stronger conception of reality based on other shared ethical or moral or religious grounds, to admit any 'reality'
other than the scientific method and mathematics, which have proven themselves as the most reliable way to see past human cultures.
Many in the scientific community are concerned about the wide disparity between how scientists work, and how their work is
perceived. Many scientists are thus involved in public education campaigns to educate lay people in high schools and colleges
about scientific skepticism and the scientific method.
Critiques of science
Paul Feyerabend argued that no description of scientific method
could possibly be broad enough to encompass all the approaches and methods used by scientists. Feyerabend objected to
prescriptive scientific method on the grounds that any such method would stifle and cramp scientific progress. Feyerabend
claimed, "the only principle that does not inhibit progress is: anything goes."
See also: social construction History of science and technology --
sociology of science -- scientific method -- epistemology -- philosophy of mathematics -- scientism -- science studies -- scientific materialism -- Consilience: The Unity of
Knowledge
History
- Empedocles
- Roger Bacon
- Galileo Galilei
- Sir Francis Bacon
- René Descartes
- Immanuel Kant
- Auguste Comte
- Charles Peirce
- Sir Karl Popper
- Michael Polanyi
- Thomas Kuhn
- Paul Feyerabend
Philosophy of Science topics
References
- Snyder, Paul, Toward One Science: The Convergence of Traditions, St Martin's Press, 1977, cloth ISBN 0-312-81011-3, paper ISBN 0-312-81012-1.
- Van Fraassen, Bas C., The Scientific Image, Oxford: Clarendon Press, 1980, ISBN 0-198-24427-4.
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