The Problems of Philosophy

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The Problems of Philosophy

• Philosophy 1
• Spring, 2002
• G. J. Mattey

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Bertrand Russell

• Born 1872
• From England
• Aristocrat
• Anti-war activist
• Won Nobel Prize for literature (1950)
• Author of popular essays
• Died 1970

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Russells Contributions

• Discovered, and tried to solve, Russells
  paradox in the theory of sets
• Published first widely-read treatise on symbolic
  logic (with A. N. Whitehead)
• Tried to reduce mathematics to logic (logicism)
• Applied symbolic logic to philosophical problems
• Co-founder of analytic philosophy (with G. E.
  Moore)

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Perceptual Relativity

• We think that our ordinary beliefs are certain,
  e.g., I am sitting at a table of a specific shape
• But these beliefs are very likely to be wrong
• We describe the table on the basis of what we see
  and feel, and we think others would describe it
  in the same way
• But the description only reflects our own point
  of view
• No two people see and feel it the same way

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Appearance and Reality

• A painter is concerned with appearance, a
  practical person with reality
• The philosopher wants to know what appearance and
  reality are
• Perceptual relativity shows that color is merely
  appearance the table has no single color
• The same considerations hold for shape, hardness
• The real table is not immediately known by sense

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Two Questions

• Is there a real table at all?
• If there is a real table, what are its real
  characteristics?
• Both are very difficult to answer

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Sense-data

• Sense-data are things immediately known in
  sensation
• Sensation is the experience of being immediately
  aware of sense data
• Colors, shapes, textures are sense-data
• So, a sensation of color is the sensation of a
  sense-datum
• The sense-data are not the table or properties of
  the table, so how are they related to the table?

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Idealism

• Objects such as tables are physical objects
• The collection of physical objects is matter
• Berkeley tried to show that matter does not exist
  at all, and at least succeeded in showing that
  its existence is not certain
• He admits that sense-data are signs of something
  mental outside us
• The real table is an idea in the mind of God

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Existential Doubt

• If we cannot be sure that matter exists, we
  cannot be sure that other people exist
• We may be all that exists (solipsism)
• Even the I might be doubted
• All that is certain is that a sense-datum is
  being perceived at a time
• This is the solid basis for knowledge

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From Sense-Data to Matter

• Do sense-data provide good evidence that physical
  objects exist?
• Common sense, on the basis of practice, answers
  in the affirmative
• There must be matter for there to be public
  objects that are neutral with respect to point of
  view
• Why believe there are such objects?

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Similarity

• One argument for public objects is that there is
  similarity in peoples sense-data
• But this begs the question, because it supposes
  that there are other people receiving sense-data
• They may be part of my dreams
• So evidence for public objects must come from our
  own private experiences

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Simplicity

• There is no contradiction in supposing that my
  private experiences have no public counterpart
• My dreams present elaborate scenes
• But it is simpler to explain my sense-data
  through public objects
• The simplicity is due to the continued existence
  of public objects, which accounts for gaps in
  sense-data
• It also accounts for behavior such as that of a
  cats exhibiting hunger

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Human Behavior

• The real advantage of public objects is in the
  explanation of human behavior
• Sounds and motions are produced that are most
  simply explained by reference to a body similar
  to my own
• Public objects can also account for dreams
• Every principle of simplicity urges us to adopt
  the natural view

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Belief in Physical Objects

• Our original belief in physical objects is
  instinctive, not demonstrative
• It seems that the sense-datum is the independent
  object (Hume)
• There is no good reason to reject the natural
  belief, given its explanatory simplicity
• It is the task of philosophy to show how our
  deepest instinctive beliefs form a system
• The possibility of error is diminished by the
  harmony of the parts of the system

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The Nature of Physical Objects

• Science has drifted into reducing the phenomena
  of nature to motion
• The motions of physical objects are not identical
  to sense-data (e.g., the light itself)
• Nor is the space we see and feel the space in
  which physical objects exist
• The space we feel and the space we touch are
  distinct (Berkeley)
• Private shapes differ when public shapes are
  static

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Correspondence

• Physical objects cause sensation through
  interaction with a physical body
• Changes in sense-data should reflect changes in
  bodily position relative to objects
• The senses testify in favor of one another
• Other people confirm what we belief
• So we may assume that there is a physical space
  corresponding to our private space

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Knowledge of Physical Space

• We can know of physical space only what is
  required to explain the correspondence
• For example, we can know that the moon, earth,
  and sun are in a line to explain the appearance
  of an eclipse
• But our knowledge is limited to relations of
  distance and does not extend to distances
  themselves

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Knowledge of Time

• The private feeling of duration is a poor guide
  to public durations
• But the order of public events corresponds to
  that of private experiences, so far as we can
  see (and this holds for space)
• The correspondence is not exact
• Lightning is really simultaneous with thunder
• The light we see left the sun eight minutes ago

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Knowledge of Physical Objects

• Differences in sense-data correspond to some
  differences in physical objects
• We have no direct acquaintance with the
  properties in the physical objects
• We know only the relations they hold to one
  another
• The intrinsic properties cannot be known through
  the senses
• It is gratuitous to think that any sense-data
  resemble properties of physical objects

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Idealism

• Idealism is the doctrine that what exists (or is
  known to exist) is in some sense mental
• This doctrine is absurd from the point of view of
  common sense
• But we only know of public objects that they
  correspond to sense-data
• We cannot reject the doctrine that the intrinsic
  character of public objects is mental simply
  because it is strange

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Berkeleys Argument for Idealism

• The existence of sense-data depends on us
• Sense-data are immediately-known ideas
• All we know immediately about common objects
  (e.g., a tree) is the sense-data
• There is no reason to think that we know anything
  else about them
• So the being of a tree is its being perceived
• Its public character is explained through God

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Fallacies

• To know a tree, it must be in our minds, but
  only as thought of
• But it does not follow that it is in our minds
  as a private object
• When I have my wife in mind, she does not exist
  there solely as a private object
• An idea exists in the mind as an act, but its
  object may be before the mind while it exists
  outside the mind

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Acquaintance

• An argument for idealism is that what we are not
  acquainted with is of no importance for us, and
  so does not exist
• It is granted that we do not know in the sense of
  being acquainted with matter
• But it is of importance to us
• And we can know things with which we are not
  acquaintedwe can know by description through
  general principles

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Knowledge of Things

• The simplest kind of knowledge of things is by
  acquaintance, as with sense-data
• Knowledge of things by description requires
  knowledge of truths general principles
• Acquaintance with does not yield knowledge of
  truths
• I know the color directly but I do not thereby
  know any truth about the color

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Knowledge by Description

• We know things by description as the so-and-so
• The table is the physical object which causes
  such-and-such sense-data
• To know the table, we must know general truths
  about causality
• Knowledge by description rests on knowledge by
  acquaintance as a foundation

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Objects of Acquaintance

• Our knowledge would be very limited if we were
  only acquainted with sense-data
• Memory extends sense-data
• We also have higher-order acquaintance with our
  states of being aware (self-consciousness)
• For example, acquaintance with seeing the sun is
  with the fact Self-acquainted-with-sense-datum
• I know that I am acquainted with this sense-datum

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Definite Descriptions

• We are also acquainted with universals such as
  whiteness, diversity, brotherhood
• This is required for the use of language
• A definite description is of the form the
  so-and-so
• When we know an object by description, we know it
  as the so-and-so
• Definite descriptions imply existence and
  uniqueness

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Knowledge by Description

• Descriptions can be nearer or further from the
  things with which we are acquainted
• We know the things described only through the
  components of a description with which we are
  acquainted
• But we can use descriptions to go beyond the
  limits of private experience, as in the case of
  physical objects