Lecture 13 Flashcards
What is a deductive argument?
An argument where premises provide logically conclusive support for the conclusion
Deductive arguments are classified as either ‘valid’ or ‘invalid’. A valid argument with all true premises is termed ‘sound’.
What is an inductive argument?
An argument where premises provide only probable support for the conclusion
Inductive arguments are classified as either ‘strong’ or ‘weak’. A strong argument with all true premises is termed ‘cogent’.
What does inductive reasoning allow us to do?
Reason ‘beyond the evidence’
This involves making generalizations based on observed instances.
List the forms of inductive argument.
- Enumerative Induction
- Statistical Syllogism
- Argument by Analogy
- Causal Argument
- Inference to the Best Explanation
Define enumerative induction.
A form of inductive reasoning where premises about a sample lead to a conclusion about the whole group
It involves drawing general conclusions based on specific observed instances.
What is a target group in enumerative induction?
The whole collection of individuals under study
What is a sample in enumerative induction?
The observed members of the target group
What is a relevant property in enumerative induction?
A property or characteristic of interest in the target group
Provide an example of enumerative induction.
40% of people in our survey said they support Party A. Therefore, we expect Party A to get 40% of votes in the election
Target group: Canadian voters; Sample: People surveyed.
What are two main ways enumerative inductions can fail to be strong?
- Sample too small
- Sample not representative
What is the fallacy of hasty generalization?
Drawing a conclusion based on a sample that is too small
What is an example of a weak argument in enumerative induction?
All corporate executives Jacques has worked for have been corrupt. Therefore, all corporate executives are probably corrupt
Sample size is too small and not representative.
What is a strong argument in enumerative induction?
Almost all blue herons examined have had birth defects, therefore most blue herons probably have birth defects
Sample is large and representative.
Why must a sample be representative in enumerative induction?
It must resemble the target group in all relevant ways
This includes having all relevant characteristics in the same proportions.
What is a biased sample?
A sample that does not accurately reflect the target group
This can happen due to selective attention.
What are opinion polls used for in enumerative inductive arguments?
To arrive at generalizations about something
What should opinion polls ensure to be strong?
- Use a large enough sample
- Generate accurate data
What is random sampling?
A method where every member of the target group has an equal chance of being selected
What is a self-selecting sample?
A process where survey subjects choose themselves
Define margin of error.
The variation between the values derived from a sample and the true values of the whole target group
What does a 95% confidence level indicate?
There is a 95% chance that the results will accurately reflect the total population
What is the relationship between sample size and margin of error?
Larger samples generally lead to smaller margins of error
What are statistical syllogisms?
Inductive arguments that apply a statistical generalization to a specific member of a group
What must be identified in a statistical syllogism?
- The individual being examined
- The group to which that individual belongs
- The characteristic being attributed
- The proportion of the group with that characteristic
Can statistical syllogisms guarantee their conclusions?
No, even good ones cannot guarantee their conclusions
Example involves a spider being assumed harmless based on a generalization.
What factors determine the strength of a statistical syllogism?
- Acceptable premises
- Statistical strength
- Typical or randomly selected individuals
What is analogical induction?
A form of reasoning where similarities between two or more things suggest further similarities
Example: If robots can move and solve problems like humans, they might also feel pain.
What criteria judge the strength of arguments by analogy?
- Relevant similarities
- Relevant dissimilarities
- Number of instances compared
- Diversity among cases
How does the number of instances compared affect analogical induction?
The greater the number of instances showing relevant similarities, the stronger the argument
What is an example of relevant dissimilarity undermining an argument?
Assuming humans give birth to puppies because they nurse their young like dogs
The relevant dissimilarity is that humans and dogs are different species.
