Framing an Experimental Hypothesis
WP5
Professor Alan K. Outram
University of Exeter
8th October 2012
Science vs. Art…
the term science is extended to denote a department of practical work which depends on the knowledge and conscious application of principles;
an art, on the other hand, being understood to require merely knowledge of traditional rules and skill acquired by habit.
Empiricism
• Empirical:– 3. In matters of art or practice: That is guided by
mere experience, without scientific knowledge; also of methods, expedients, etc.
• Empiricism:– 2. a. The use of empirical methods in any art or
science. b. Philos. The doctrine which regards experience as the only source of knowledge.
(definitions from OED)
Induction
• 6. The bringing forward, adducing, or enumerating of a number of separate facts, particulars, etc., esp. for the purpose of proving a general statement.
Strong Induction
All observed crows are black
Therefore:
All crows are black
Weak Induction
Many speeding tickets are given to teenagers
Therefore:
All teenagers drive too fast
Induction is Probabilistic
As evidence accumulates, the degree to which it comes to support a hypothesis, should tend to indicate that false hypotheses are probably false and true ones are probably true.
Deduction
• Premises logically entail the conclusion• The truth of the premises provide a guarantee
of truth to the conclusion.
Deduction example 1
All animals are mortal.All humans are animal.
Therefore:
All humans are mortal.
Deduction example 2
All apples are fruit.All fruits grow on trees.
Therefore:
All apples grow on trees.
Hypothetico-Deductive reasoning
Experiment• 1. a. The action of trying anything, or putting it
to proof; a test, trial • 3. An action or operation undertaken in order
to discover something unknown, to test a hypothesis, or establish or illustrate some known truth. a. in science.
“All knowledge is provisional, conjectural and hypothetical”
Falsification
• Theories (hypotheses) must be tested against empirical knowledge, through experimentation.
• Theories are not held to be true (verified) if they pass such tests, they merely remain valid until falsified or superseded
• Exceptions do not prove the rule, they falsify it!
Framing Good Experimental Hypotheses
• Prioritise hypotheses that are not trivial, particularly those premises which have wide relevance and scope.
• Is the hypothesis testable (i.e. is it possible to falsify it, both in theory and practice)?
• Keep the hypothesis simple: often best to test one thing at a time. For more complex questions, test multiple, simple hypotheses.