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A concise overview of inductive and deductive arguments, including key concepts such as premises, conclusions, validity, strength, and soundness. It covers different types of arguments, including sentential and categorical deductive arguments, as well as arguments from analogy, authority, inductive generalization, statistical syllogism, and evidence. The document also distinguishes between arguments and non-arguments, such as descriptions, narratives, illustrations, and explanations. It is a useful resource for students studying logic and critical thinking, offering clear definitions and examples to aid understanding. This material is suitable for university and high school students.
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Deductive Argument ✔✔if all the premises are true then the conclusion must be true.
Inductive Argument ✔✔if all the premises are true then there is a high probability that the conclusion is true, but do not guarantee the truth of the conclusion.
Premises ✔✔constitutes the basis for accepting the truth of the conclusion. The truth of these is taken for granted.
Conclusion ✔✔the statement the arguer wants you to believe
Sorites ✔✔A collection of arguments.
Valid/Invalid ✔✔Deductive Arguments are ____ or _______. Because of the nature of deductive arguments, there is no degree of this.
Strong <--> Weak ✔✔Inductive Arguments can be ______ or ______. Because of the nature of inductive arguments, there is a scale (degree) of this.
Degree of Strength ✔✔Inductive arguments exist on a scale. The degree of strength can vary. There is no degree of validity (deductive arguments) because a deductive argument is either valid or invalid.
Valid ✔✔In a deductive argument, if all the premises are true, then the conclusion MUST be true. Thus the argument is ______. This is dealing with the relationship between the premises and the conclusion and not the actual truth-value of the statements. The argument is ____________ when the truth of the premises 100% entails the truth of the conclusion.
Invalid ✔✔In a deductive argument, if it is possible for the premises to be true and the conclusion false, then the argument must be _____.
An example of a deductive argument ✔✔All men are mortal. (premise)
Socrates was a man. (premise)
Socrates was mortal. (conclusion)
Strong ✔✔An inductive argument where the premises do provide inductive support for the conclusion, and the more likely the truth of the conclusion becomes.
Weak ✔✔An inductive argument where the premises do not provide inductive support for the conclusion, and does not increase the probability of the truth of the conclusion.
Inductively Sound ✔✔When an inductive argument is inductively strong and the premises are all true.
Inductively Unsound ✔✔When an inductive argument is weak or has at least one false premise.
Reasonable ✔✔An argument that is either Valid or Strong.
Cogent ✔✔Reasonable+Sound=_____
or
Deductive: Valid+Sound=_______
Inductive: Strong+Sound=_______
The two kinds of Deductive Arguments ✔✔Sententional (Propositional)
Categorical
(D) Sententional (Propositional) ✔✔You're not arguing either par of the compound statement in the premises.
if/then
either/or
not/and
if and only if
Example:
Either tea is on sale or coffee is on sale
Tea is not on sale
Coffee is on sale
(D) Categorical ✔✔All premises as well as the conclusion assert a relationship between classes or asserts that an individual is or is not a member of a class.
Example:
-Both the fruit of the tomato plant and the fruit of the nightshade plant are brightly colored berries that are produced on plants that are members of the same plant family.
-The fruit of the nightshade plant is poisonous.
The fruit of the tomato plant is poisonous.
(I) Argument from Authority ✔✔An arguer claims that an authority says a statement is true.
Example:
(Authority) says that (argument) is true
(argument) is true.
Example 2:
Plato considered knowledge to be a kind of justified true belief.
Knowledge probably is a sort of justified true belief
(I) Inductive Generalization ✔✔An arguer infers the truth of a generalization from the observation that the generalization is consistent with what has been seen to hold true in a limited number of cases.
There are three types:
Induction by Enumeration
Narrow scope to broad scope induction.
Statistical induction
What is an induction by enumeration? ✔✔A type of inductive generalization where the premises of the argument state that the relation between two things holds in a number of specific cases, so it probably holds in all cases.
Example:
The crow I saw yesterday was a big black bird.
The crow I saw this morning was a big black bird.
The crow I saw an hour ago was a big black bird.
(I) Statistical Syllogism ✔✔it is noted that a relation between two classes, a reference class and a target class, holds in a large percentage of cases. A particular individual is then cited as belonging to the reference class, and the conclusion drawn is that the individual is also a member of the target class (a), or is not a member of the target class.(b)
Example (a):
-90% of the people who voted Republican in the last election are people who will vote Republican in the next election.
-Bob voted Republican in the last election.
Bob will vote republican in the current election
Example (b):
-Only 10% of Democrats who voted Republican in the last election are people who will vote Republican in the current election.
Bill is a democrat who voted in Republican in the last election.
Bill will not vote Republican in the current election.
(I) Argument from the Evidence ✔✔Where evidence from varied sources is given to show why the conclusion is probably true. Also called an inference to the best explanation.
Example:
-Smith was acquainted with the murdered man.
-Smith and the murdered man were both seen at the bar the night of the murder.
-Traces of blood of the same type as that of the murdered man were found on the coat that Smith wore the night of the murder.
-A person fitting Smith's description was seen driving away from the scene of the crime shortly after the murder.
Smith murdered the man.
Name the types of non-arguments: ✔✔Description
Narrative
Illustration
Explanation
What is an action explanation? ✔✔The actions of an agent are accounted for or made sense of in terms of those beliefs, intentions, and/or desires that motivated the agent's behavior.
What is a functional explanation? ✔✔The features of a thing are explained in terms of the function, role, or purpose those features serve.
Refutation ✔✔An argument that the argument is not cogent.
Vagueness ✔✔if it is imprecise in that its exact range of application is not made clear from the context.
Ambiguity ✔✔if it is imprecise in that it can be interpreted in more than one way
Syntactic ambiguity ✔✔if it is ambiguous because of sentence structure
Semantic ambiguity ✔✔if it is ambiguous because a word used has multiple meanings.
What are the forms of Doublespeak? ✔✔Slanting
Biasing
Puffery
Gobbledygook
Pacifier
What is the three way test for determining the believability of unsupported claims? ✔✔1) Is the claim sensible and understandable?
Does it come from a reliable source?
Is the claim consistent with your background knowledge?
What are the factors that determine the reliability of the source? ✔✔1) area of expertise or position of observer
education, training, or experience
record of reliability
possible ulterior motive
possible bias
reputation among peers
possibility of 'getting away with' a lie or error
Cognitive Content ✔✔the descriptive or objective content of a word or expression.
Emotive Force ✔✔the evaluative or subjective content of a word or expression
Denotative meaning ✔✔the literal (or dictionary) definition.
Connotative meaning ✔✔suggested or implied meaning.
Conversational implication ✔✔when you imply something but never say it literally.