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  • 8/13/2019 Unidad2 PSC


  • 8/13/2019 Unidad2 PSC


  • 8/13/2019 Unidad2 PSC


  • 8/13/2019 Unidad2 PSC


    Introduction: Inductivism

    Inductivism: From observation arisesgeneral theories (Francis Bacon,John Stuart Mills)

    42012 M. Arias

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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

    52012 M. Arias

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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

    62012 M. Arias

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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

    72012 M. Arias

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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.


    "metals expand when heated"

    "acids tum litmus red

    92012 M. Arias

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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.

    102012 M. Arias

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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.

    112012 M. Arias

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    The appeal of inductivism

    142012 M. Arias

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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

    152012 M. Arias

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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

    proven, just disproven182012 M. Arias

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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.



    2012 M. Arias

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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.

    2012 M. Arias

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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.

    2012 M. Arias

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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

    2012 M. Arias

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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


    Rays of light bendin the presence of agravitational field.

    Falsifiability as a criterion for theory

    2012 M. Arias 24

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    Degree of falsiability:


    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.

    2012 M. Arias

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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.

    262012 M. Arias

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    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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    2012 M. Arias28