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Logical Empiricism

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8/22/09. Logical Empiricism. Jay Odenbaugh. Philosophy. Lewis and Clark College. 8/22/09 ... If one is justified in a belief, then one must have evidence for ... – PowerPoint PPT presentation

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Title: Logical Empiricism


1
Logical Empiricism
  • Jay Odenbaugh
  • Philosophy
  • Lewis and Clark College

2
Empiricism - The View
  • Empiricism is the thesis that experience is the
    only source of knowledge.
  • If one is justified in a belief, then one must
    have evidence for the belief from one of your
    senses.

3
One Problem - Skepticism
  • If one is justified in a belief, then one must
    have evidence for the belief on the basis of
    ones senses.
  • However, one cannot have empirical evidence for
    the existence of the external world on the basis
    of the senses since we have no access to it.
  • Therefore, one is not justified in believing in
    an external world.

4
Trees fallingBerkeley and Phenomenalism
  • George Berkeley was a phenomenalist material
    objects consist in experiences or possible
    experiences.
  • Thus, there is no world independent of the
    mind.
  • Of course, Berkeley recognized that there are
    objects that exist even if we do not perceive
    them. Thus, he cited God as the permanent
    perceiver holding all objects in existence.

5
Rationalism - An Epistemology made in Heaven
  • Rationalism the thesis that experience is not
    the only source of knowledge.
  • Rationalists included Rene Descartes and Gottleib
    Leibniz.
  • They argued that areas of inquiry like
    mathematics formed an important source of
    knowledge and it did not derive from experience
    but rather from pure thought.

6
Mathematical Knowledge?
  • Mathematics has been a source of trouble for
    empiricism how can we have knowledge of these
    objects that cannot be experienced? Consider the
    following true claim
  • The set of natural real numbers ? is larger than
    the set of natural numbers N.
  • How can we know that this is true on the
    empiricists account?

7
Logical Positivism and Empiricism
  • Logical positivism is a strain of empiricism that
    arose in Europe after WWI though a group of
    scholars in Vienna, Austria Moritz Schlick,
    Otto Neurath, Rudolf Carnap, Hans Reichenbach (in
    Berlin) and others and formed the Vienna
    Circle.
  • They were impressed by recent work in
    mathematics, logic, and physics particularly
    Albert Einsteins theories of relativity and were
    opposed to idealism. Idealism is the view that
    reality is in some sense mental or spiritual.

8
Logical Positivism and Empiricism, Cont.
  • LP was a liberal group.
  • Most were democratic socialists.
  • Likewise, many were Jews and the bulk of them
    fled Germany for England and the United States
    during WWII.

9
The Fundamentals - Analytic/Synthetic Distinction
  • Fundamental ideas of logical positivism are the
    analytic/synthetic distinction and the
    verifiability theory of meaning.
  • According to LP (and others before), there are
    two types of statements.
  • A statement is analytic if, and only if, it is
    true in virtue of its meaning and nothing else.
  • A statement is synthetic if, and only if, it is
    true in virtue of (1) its meaning and (2) the way
    the world is.

10
Analytic/Synthetic Distinction, Cont.
  • Examples of an analytic claims are All bachelors
    are unmarried and dx2/dt 2x.
  • An example of a synthetic claim is Jack is a
    bachelor. Likewise, All bodies fall to the
    center of the Earth when dropped.
  • LP argued that logical and mathematical claims
    are analytic.

11
Aposteriori and A Priori Knowledge
  • From Immanuel Kant we have,
  • A statement is a priori if, and only if, it can
    be known independent of experience.
  • A statement is a posteriori if, and only if, it
    cannot be known independent of experience.

12
Aposteriori and A Priori Knowledge, Cont.
  • Thus, this gave them the following table.
  • A priori A posteriori
  • Analytic Mathematical claims None
  • Synthetic None Scientific claims
  • Not everyone agrees that there is synthetic a
    priori knowledge for example, Every event has a
    cause.

13
The Fundamentals - The Verifiability Theory of
Meaning
  • Another important issue was the verifiability
    theory of meaning.
  • A synthetic statement is meaningful if, and only
    if, it can be verified in principle.
  • If we are to verify a statement we must evaluate
    its truth in accordance with experience
    understood as observation.

14
Verifiability Theory of Meaning, Cont.
  • LP argued that ethical statements, religious
    statements, and much of literature were
    meaningless in the sense above.
  • This also provided a way for them to criticize
    philosophy like idealism. For example, Hegel
    wrote,
  • Reason is substance, as well as infinite power,
    its own infinite material underlying all the
    natural and spiritual life as also the infinite
    form, that which sets the material in motion.

15
The Fundamentals - The Observational/Theoretical
Term Distinction
  • LP also distinguished between observational terms
    and theoretical terms. Green is an
    observational term, gene is not.
  • Observational terms refer to observable objects,
    processes, and events theoretical terms do not.
  • LP spilled much ink on this issue because on
    their view scientific theories consisted in a set
    of statements and those statements contained both
    observational terms and theoretical terms.

16
The Fundamentals - The Context of Discovery and
the Context of Justification
  • Hans Reichenbach argued for a context of
    discovery and context of justification they
    dismissed history, sociology, and psychology of
    science as relevant to the latter.
  • Why someone has some particular idea or how it
    originated is irrelevant to whether they should
    believe it.
  • What causes someone to hold a belief is
    irrelevant - what is their evidence.

17
Problem One
  • Suppose All planets travel in elliptical orbits
    is testable or meaningful.
  • It is presumably true then that All planet
    travel in elliptical orbits or there are 5,472
    angels in heaven. This would be true even if the
    There are 5,472 angles in heaven is not
    testable.
  • If a statement P is meaningful, then (P ? Q) is
    meaningful as well.

18
Problem Two
  • The verifiability theory of meaning is a
    statement
  • A statement is meaningful if, and only if, it can
    be verified in principle.
  • How can one verify the verification principle?

19
Problem Three
  • W. V. Quine in Two Dogmas of Empiricism argued
    that individual statements are not verifiable in
    isolation.
  • For example, neither Newtons 3rd law of motion
    nor his law of gravitation make predictions by
    themselves.
  • F ma fab gmamb/d2
  • One must measure the parameters with the relevant
    instruments. Ultimately, we test bundles of
    hypotheses.

20
Problem Three, Cont.
  • Quine argued for a holistic theory of testing.
  • Testing has the following form
  • (Hypothesis Auxiliary Initial Conditions) ?
    Prediction

21
Problem Four
  • He also argued there was no analytic/synthetic
    distinction rather, all there is a web of
    belief.
  • Analytic statements are relatively immune to
    revision and are close to the center of the web.
    Observational claims are at the periphery.
  • Quantum mechanics might have us revise basic
    logical principles like the principle of
    non-contradiction. Light is both a particle and
    a wave.

22
Conclusion
  • LP and LE were extremely worried about the status
    of metaphysical sounding stuff and so they
    worried about positing things that we have little
    access to.
  • That is, they were not terribly congenial to a
    view called scientific realism. The main goal of
    science is prediction get the observations
    right.
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