Scientific Explanation

1
Scientific Explanation

• Suppose we assume that explanation and prediction
  of phenomena are the goal/purpose of science
• Suppose we also assume that any account of
  explanation needs to incorporate logic and
  experience
• Hempels D-N model of explanation
• D Deductive
• N Nomological (i.e., law like)
• Hempels model is formal and deductive

2
Scientific Explanation

• E An event to be explained The water in my car
  radiator froze last night.
• How to explain this?
• (Relatively) pure water freezes at 32 degrees.
• My car radiator contains (relatively pure water)
  AND the temperature last night was below 32
  degrees.
• --------------------------------------------------
  ----------
• Therefore, E (the water in my car radiator
  froze)

3
Scientific Explanation

• E An event to be explained The water in my car
  radiator froze last night.
• How to explain this?
• Hempels model
• L1, L2 LN
• C1, C2 CN
• --------------------
• E
• If some phenomenon, E, can be subsumed under
  law-like generalizations and initial conditions
  (i.e., derived from the) that that phenomenon is
  explained.

4
Scientific Prediction

• E An event predicted The water in my car
  radiator will freeze last night.
• Hempels model
• (Relatively) pure water freezes at 32 degrees (L)
• My car radiator contains relatively free water
  and the temperature tonight will go below less
  than 32 degrees (C1 and C2).
• --------------------------------------------------
  ------------------
• So, the water is my car radiator will freeze
  tonight (E).

5
Scientific Explanations and Predictions

• Challenges to Hempels model of explanation
• What about sciences (such as many fields in
  biology) that do not have law-like statements?
  Are they not able to offer explanations?
• Hempel Some sciences include probabilistic
  generalizations from which probable explanations
  and/or predictions do follow.
• The problem of asymmetry examples in which while
  two statements can be derived from each other,
  only one way of construing their relationships is
  reasonably causal.

6
Scientific Explanations and Predictions

• Challenges to Hempels model of explanation
• The problem of asymmetry examples in which while
  two statements can be derived from each other,
  only one way of construing their relationships is
  reasonably causal.
• E A flagpole casts a particular shadow.
• Cs The height of the flagpole and the angle of
  the sun relative to the flagpole.
• Which explains which?
• It appears that statements of the form C explains
  E, but not vice versa.

7
van Fraassens account of Scientific Explanations

• Explanation is not a formal relationship (defined
  in terms of logic)
• It is a pragmatic relationship context and
  practice dependent
• Why questions are asked, and regarded as
  answered, within specific contests
• To understand them (and just what will count as
  an explanation) requires knowledge of the
  scientific context within which they are asked.
• Example Why sex?