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.

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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.

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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.

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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.

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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?

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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?

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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.

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Problem Three, Cont.

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

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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.

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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.