chpater 8 cont

# chpater 8 cont - 1 Logic and reasoning[15 19 Oct rest of...

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Unformatted text preview: 10/19/2011 1 Logic and reasoning [15] 19 Oct rest of Chapter 8 Inductive reasoning • Two kinds of arguments- Deductive- Inductive- Deductive: conclusion follows 100%- Inductive: … less than 100% • Three types of inductive arguments- Enumerative induction (parts b whole)- Analogical induction (X :: Y b A :: B)- Causal induction / reasoning (shared causal properties) Enumerative Induction: An inductive argument pattern in which we reason from premises about individual members of a group to conclusions about the group as a whole . X % of the observed members of group A have property P. Therefore, X % of all members of group A probably have property P. General pattern • Target group (or target population)—In enumerative induction, the whole collection of individuals under study. • Sample (or sample member)—In enumerative induction, the observed members of the target group. • Relevant property (or property in question)—In enumerative induction, a property, or characteristic, that is of interest in the target group. • Two issues with the sample- Too small- Not representative 10/19/2011 2 • Hasty generalization —The fallacy of drawing a conclusion about a target group based on an inadequate sample size. • Biased sample —A sample that does not properly represent the target group. • Representative sample —In enumerative induction, a sample that resembles the target group in all relevant ways. Recap • Hasty generalization —The fallacy of drawing a conclusion about a target group based on an inadequate sample size. • Biased sample —A sample that does not properly represent the target group. • Representative sample —In enumerative induction, a sample that resembles the target group in all relevant ways. Recap Random sample — A sample that is selected randomly from a target population in such a way as to ensure that the sample is representative. In a simple random selection, every member of the population has an equal chance of being selected for the sample. • The motel example:- The sample wasn’t random- The front people are chosen to be nice, so the selection of whom we met is not random- Weak argument: not because of the sample size, but because of bias… • Recap When enumerative induction matters a lot:- Drug testing • Target population (Tp): all people suffering of a certain disease • Sample (S): volunteers (among those suffering) • Property (P): getting cured / adverse effects The bigger the sample, the better The more representative sample, the better = the more random (= diverse), the better Volunteering problem The longer the testing, the better When enumerative induction matters a lot:- Opinion polling • Target population (Tp): all voters • Sample (S): people chosen by the pollsters • Property (P): voting a certain way / candidate The bigger the sample, the better The more representative sample, the better = the more random (= diverse), the better Polling problems • Opinion polls- Key-question: do they generate accurate data?Key-question: do they generate accurate data?...
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## This note was uploaded on 12/20/2011 for the course PHIL 102 taught by Professor Rug during the Fall '11 term at University of Illinois, Urbana Champaign.

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chpater 8 cont - 1 Logic and reasoning[15 19 Oct rest of...

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