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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?

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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

Falsifiability as a criterion for theory

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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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