Reason Deductive and Inductive Reasoning
Deductive reasoning • Reason from the General to the Particular • All metal expand when heated X is metal Therefore X expands when heated
Deductive reasoning Value of Deductive reasoning More certain, but less informative than induction
Deductive reasoning Deductive reasoning is seen as an instrument for the preservation of the truth. Unfortunately it is not really the source of the truth (not all arguments are true, even if they are valid)
Inductive reasoning • Reasoning from particular to general • Metal X expands when heated Metal B expands when heated Metal C expands when heated Therefore all metals expand when heated
Inductive reasoning Value of Inductive reasoning More informative, but less certain than deduction
Inductive reasoning How reliable is inductive reasoning? We tend to make hasty generalisations we often jump conclusions without considering enough evidence.
Inductive reasoning Inductive reasoning and Confirmation Bias People remember only evidence that will support their beliefs…
Inductive reasoning What distinguishes good generalisations? • Number (the more the better) • Variety (variety of circumstances better) • Exceptions (look for counter examples, guard against confirmationbias) • Coherence (demand more evidence for surprising claims) • Subject area (be aware of subject area natural or social sciencesetc)
Task • Read Sherlock Holmes pg 4 to 21 (up to start of chapter 8) What is the solution to the mystery? How did Sherlock Holmes figure it out? (read rest of pg.21 and 23) • Read story on pg.122, answer Questions 1-11 • Pg. 120 Question 2 (middle of page) • Journal : Do you use deductive or inductive reasoning?