Quine,

1
Quine, Natural Kinds

• Some Problems of Induction
• (1) The New Riddle of Induction (Goodman)
• Goodman proposes a new predicate grue.
• X is grue if and only if it is examined before t
  and is green, or it has not been examined before
  t and is blue.
• Now, lets suppose t is now. The following
  inductive inferences would seem to be equally
  well justified.
• Emerald 1 is green, emerald 2 is green, So, the
  next emerald will be green.
• Emerald 1 is grue, emerald 2 is grue, So, the
  next emerald will be grue (i.e. blue).

2

• In other words, we are equally justified in
  expecting the next emerald to be grue as we are
  in expecting it to be green. But, if it is grue,
  it is blue and not green.
• Goodmans questions are then the following
  What makes a statement genuinely lawlike? What
  allows us to recognize some predicates (like
  green) as good, respectable predicates and to
  disregard other predicates? What makes one
  predicate projectible, another not?

3

• Goodman The real inadequacy of Humes account
  lay not in his descriptive approach but in the
  imprecision of his description. Regularities in
  experience, according to him, give rise to habits
  of expectation and thus it is predictions
  conforming to past regularities that are normal
  or valid. But Hume overlooks the fact that some
  regularities do and some do not establish such
  habits that predictions based on some
  regularities are valid while predictions based on
  other regularities do not To say that valid
  predictions are those based on past regularities,
  without being able to say which regularities, is
  thus quite pointless. Regularities are where you
  find them, and you can find them anywhere. (4th
  ed., p. 82)

4
Back to Quine

• What makes Goodmans example a puzzle, however,
  is the dubious scientific standing of a general
  notion of similarity. The dubiousness of
  this notion is itself a remarkable fact. For
  surely there is nothing more basic to thought and
  language than our sense of similarity our
  sorting of thing into kinds. (234a)
• There is something wrong with taking similarity
  to be a matter of set membership. Similarity is
  a matter of degrees set membership isnt.

5

• Similarity is, however, necessary for the
  learning of language. For one learns a language
  (wholly or in part) through ostension.
• A standard of similarity is in some sense
  innate. (236a)

6

• To trust induction as a way of access to the
  truths of nature is to suppose, more nearly,
  that our quality space matches that of the
  cosmos. The brute irrationality of our senses of
  similarity, its irrelevance to anything in logic
  and mathematics, offers little reason to expect
  that this sense is somehow in tune with the world
  a world which, unlike language, we never made.
  Why induction should be trusted, apart from
  special cases such as the ostensive learning of
  words, is the perennial philosophical question of
  induction. (237ab)

7

• Philosophy and science work together and are in
  the same boat Neuraths boat.
• For me, then, the problem of induction is a
  problem about the world a problem of how we, as
  we now are, in a world we never made, should
  stand better than random or coin-tossing chances
  of coming out right when we predict by inductions
  which are based on our innate, scientifically
  unjustified similarity standard. Darwins
  natural selection is a plausible partial
  explanation. (237b)

8

• Things are similar in the later or theoretical
  sense to the degree that they are interchangeable
  parts of the cosmic machine revealed by science.
  (240a)
• In general we can take it as a very special
  mark of the maturity of a branch of science that
  it no longer needs an irreducible notion of the
  similarity and kind. It is the final stage where
  the animal vestige is wholly absorbed into the
  theory. In this career of the similarity notion,
  starting in its innate phase, developing over the
  years in the light of accumulated experience,
  passing then from the intuitive phase into
  theoretical similarity, and finally disappearing
  altogether, we have a paradigm of the evolution
  of unreason into science. (241b)
• Oh, really??