Chapter 27: Hypotheses, Explanations, and Inference to the Best by rgrVhQ3


									       Chapter 27:
Hypotheses, Explanations,
      and Inference
 to the Best Explanation
       Explanations (p. 294)
• Explanations answer the questions Why?
  or How?
• The search for explanations often goes by
  way of hypotheses.
        Evaluating Hypotheses
            (pp. 294-299)
• A. The hypothesis must have all the
  properties for which you look in any
  – 1. The hypothesis must not merely redescribe
    the phenomenon in different words.
     • The “phenomenon” is the event to be explained. It
       might be a physical phenomenon, the behavior of
       a person, etc.
  – 2. The hypothesis must be free from
     • No word should have more than one meaning as
       employed in the explanation.
         Evaluating Hypotheses
             (pp. 294-299)
  – 3. The hypothesis must be consistent; that is, the
    hypothesis must not entail self-contradictory
  – 4. The hypothesis and predictions made on the basis
    of the hypothesis must be precise.
• B. Hypotheses explain phenomena and
  provide the basis for predictions and
  – Predictions concern events in the future.
  – Retrodictions concern events in the past. If a
    retrodiction is correct, it might help you uncover some
    unnoticed historical event, for example.
         Evaluating Hypotheses
             (pp. 294-299)
• C. Criteria for evaluating hypotheses
  – 1. A hypothesis must be testable.
     • There must be a procedure for determining whether the
       predictions (retrodictions) proposed by the hypothesis can be
  – 2. If predictions based upon a hypothesis are true,
    this tends to show that that the hypothesis is true.
     • a. Confirming a hypothesis and the argument form affirming
       the consequent.
         – This, of course, provides only inductive evidence that the
           hypothesis is true.
    Evaluating Hypotheses
        (pp. 294-299)
• b. Falsifying a hypothesis and denying the consequent
    – This provides conclusive evidence that either the hypothesis or some
      unstated assumption (part of a more general theory, for example) is
    – In practice, well-confirmed hypotheses might not be rejected until there
      is an alternative hypothesis that explains both the anomalous
      phenomenon and why the original hypothesis failed. While certain
      predictions based on Newton’s Theory were proven false in the mid-
      nineteenth century, Newton’s Theory remained in use until it was
      supplanted by Einstein’s Theory, which explained both the anomalous
      phenomena and determined the limits of Newton’s Theory. (Newton’s
      Theory works very well for “middle-sized” objects: larger than
      subatomic particles and smaller than galactic systems.)
       Evaluating Hypotheses
           (pp. 294-299)
– 3. A hypothesis is more probably true if it has a
  broader explanatory scope, that is, if it explains more
  phenomena than alternative hypotheses.
   • Consilience is the tendency of several forms of inductive
     evidence to point to the same conclusion.
   • Explanatory scope is the class of phenomena a hypothesis
     will explain.
– 4. If either of two hypotheses will explain a
  phenomena and one involves fewer theoretical
  assumptions, the hypothesis that involves fewer
  assumptions is more probably true.
   • Simplicity: The hypothesis with fewer theoretical
     assumptions is said to be the simpler hypothesis.
   • The Principle of Parsimony or Ockham’s Razor (named after
     the 13th century English philosopher William of Ockham) is
     the principle that the theoretically simplest theory is most
     probably true.
       Evaluating Hypotheses
           (pp. 294-299)
– 5. A hypothesis is more probably true if it is consistent
  with the best theoretical explanations available.
   • 1. The theory guides you regarding what are probably
     relevant hypotheses.
   • 2. Theories explain.
   • 3. Theoretical explanations are conservative.
       – Novel explanations must be shown superior to explanations
         that are already accepted.
– 6. A hypothesis is more probably true if it is fruitful,
  that is, if it predicts previously unknown phenomena.
   • The first five criteria apply to cases of troubleshooting as well
     as scientific hypotheses. This one is concerned primarily
     with the acceptance of broader theories, that is, scientific and
     historical theories, for example.
      Examples (pp. 300-308)
• Troubleshooting
  – Consider the procedures you undertake in trying to
    figure out why an ordinary, everyday thing isn’t
    working properly. Why won’t your car start? Why
    does water periodically flow into the tank of your
    toilet? Why does your InkJet printer smear the ink?
• B. Theories
  – An explanatory theory consists of a number of well-
    confirmed, interrelated hypotheses that explain a
    phenomenon of a certain kind.
  – 1. The crash of Stardust
  – 2. Madam Curie and the discovery or radium
   Examples (pp. 300-308)
  • a. Internal consistency
     – A theory, or any other kind of discourse, is internally
       consistent if and only if there are not two or more
       propositions that can be combined to form a
  • b. External consistency
     – In the sciences, external consistency is the consistency
       between claims made by a hypothesis for which there
       appears to be evidence and the ongoing theoretical
       assumptions of a science.
– 3. Barry Marshall and the cause of ulcers
– 4. Barbara McClintock
 Arguments to the best explanation
          (pp. 300-308)
• The best explanation is that which is so judged
  on the basis of the criteria for evaluating
  hypotheses. For example, if you have two
  hypotheses and one hypothesis is theoretically
  simpler than the other, then, all things being
  equal on the basis of the other criteria, the
  theoretically simpler hypothesis provides the
  better explanation.
• Arguments to the best explanation always
  involve two or more hypotheses.
  – 1. Causal situations
  – 2. Literary interpretation

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