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Introduction: Inductivism
Inductivism: From observation arisesgeneral theories (Francis Bacon,John Stuart Mills)
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Deductive logic (drastically oversimplified):
All A are B.
X is an A.
Therefore X is B.
Inductive logic
All copper we have tested conducts electricity.
X is a piece of copper yet to be tested.
Therefore X will conduct electricity.
Introduction: Inductivism
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The logic of induction (David Hume Scottish
empiricist 1711-1776)
All A observed so far are B. [i.e. All A are B]
X is an A not yet observed. [i.e. X is not an A]
Therefore X is B. [X is B.]
Introduction: Inductivism
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The logic of induction ( David Hume)
Example 1
1. All books on philosophy are boring.2. This book is a book on philosophy.
3. This book is boring.
1& 2 premises
3 Conclusion
Introduction: Inductivism
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Can scientific laws be derived from
the facts?
It can be straightforwardly shown that
scientific knowledge cannot be derived fromthe facts if "derive" is interpreted as"logically deduce.
Examples:
"metals expand when heated"
"acids tum litmus red
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Can scientific laws be derived from
the facts?Premises :
1. Metal X1 expanded when heated on occasion t12. Metal X2 expanded when heated on occasion t2
n. Metal Xn expanded when heated on occasion tn
ConclusionAll metals expand when heated
It is simply not the case that if the statementsconstituting the premises are true then the
conclusion must be true.
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What constitutes a good inductive
argument?If an inductive inference from observable facts
to laws is to be justified, then the following
conditions must be satisfied:
1. The number of observations forming the basis of a
generalization must be large.
2. The observations must be repeated under a wide variety
of conditions.
3. No accepted observation statement should conflict withthe derived law.
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The appeal of inductivism
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The appeal of Inductivism
Three Approaches To Explanation
A philosopher of science asks: What is the differencebetween describing a phenomenon and explaining it?
In addition, what makes something an adequateexplanation? Philosophers have defended three basicanswers to this question
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The appeal of Inductivism1 Inferential View (Carl G. Hempel, Paul Oppenheim)
An explanation is a type of argument, with sentences
expressing laws of nature occurring essentially in thepremises, and the phenomenon to be explained as the
conclusion.Also included in the premises can be sentences describing
antecedent conditions.
2 Causal View (Wesley Salmon, David Lewis)
An explanation is a description of the various causes of the
phenomenon: to explain is to give information about thecausal history that led to the phenomenon.
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Falsificationism(Karl Popper 1902-1904)
Popper (1934): Theories cannot be
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Scientific theories are never truly verified. Moreover, to
be always verified is not a virtue in a scientific theory.
Verification and falsification are asymmetrical:
No accumulation of confirming instances is sufficient to
verify a universal generalization.
But only one disconfirming instance suffices to refute a
universal generalization.
Scientific theories are distinguished by the fact that they
are capable of being refuted. They are falsifiable.
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Falsificationism
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Falsificationism(Carnap vs. Popper)Rudolph Carnap is an inductivist, (the Vienna cirlce) and
in this respect he differs from Popper.
However, both agree (taking inspiration from Hume) thatthere is a serious problem with the justification of
"inductive inference."
Carnap discusses it in terms of a puzzle about how we
arrive at and form opinions regarding laws.
Laws are universal statements (at least), hence apply to
an at least potentially infinite domain. However, ourempirical data is always finite.
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Here are some examples of some simple assertions thatare falsifiable in the sense intended.
1. It never rains on Wednesdays.
2. All substances expand when heated.
3. Heavy objects such as a brick when released near the
surface of the earth fall straight downwards if not impeded.
4. When a ray of light is reflected from a plane mirror, theangle of incidence is equal to the angle of reflection.
Falsifiability as a criterion for theory
Both 3 and 4 are falsifiable, even though they may be true.
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Pseudo-science: A theory withthe empirical trappings of realscience, including a system oftheoretical concepts and a
wealth of corroboratingevidence.
But a pseudo-science has built-
in defense mechanismsagainst possible refutation.
The Freudian theory provides an
interpretation for everyconceivable symptom of thepatient.
Its predictions therefore cannever be refuted. 22
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Einsteins General Relativity: If it hadfailed its famous test of 1919, no onewould have taken it seriously.
But it passed the test, and Newtons
theory of gravitation was refuted.
Albert Einstein (1879-1955)
On the electrodynamics of
moving bodies (1905)
The foundation of the
general theory of relativity
(1916) 23
Falsifiability as a criterion for theory
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Empirical test of general relativity vs.Newtonian gravitation:
Light from a star
passing near the Sunshould be deflected.The evidence is the
displacement of thestars apparent
position.
Rays of light bendin the presence of agravitational field.
Falsifiability as a criterion for theory
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Degree of falsiability:
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Highly falsifiable theories should bepreferred to less falsifiable ones, then,
provided they have not in fact been falsified.
The qualification is important for thefalsificationist.
Theories that have been falsified must beruthlessly rejected.
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Falsificationism and progress:
Science starts with problems, problems
associated with the explanation of the behaviour
of some aspects of the world or universe.
The progress of physics from Aristotle through
Newton to Einstein provides an example on a
larger scale.
The falsification of Einteins theory remains a
Challenge for modern physicists.
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References
What is this thing called Science?.
(Chapter 4 & 5).
An Introduction to the Philosophy ofScience: Theory and Reality(Chapter 3 & 4).
Philosophy of Science: The Central IssuesMartin Curd and J. A. Cover (Chapter 1)
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