Framing an Experimental Hypothesis WP5 Professor Alan K. Outram University of Exeter 8 th 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 Theories are not held to be true (verified) if they pass such tests, they merely remain valid until falsified or superseded Exceptions do not prove the rule, they falsify it!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.