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Logic:
The study of the methods and principles used to distinguish correct from incorrect reasoning
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Argument:
from logitians point of view, is a series of propositions, some of which are premises, others of which are conclusions
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Logic is not:
- 1. Science of thought (psychology)
- 2. Science of reasoning(cog. psy.)
- 3. The art of persuasion "rhetoric"
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We are interested in:
causes us to think the way we do
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Propositions, while expressed by sentences:
they are not equivalent to sentences
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Questions and explanations :
are sentences but not propositions
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Commands:
- are sentences but not propositions
- These Can be turned into propositions though
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Example of command:
Do your homework -> You should doyour homework if you want topass the class.
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Temporal relations;
- prop. that appears to be butisnt
- one indicating a before and after
- ex. since the nig has been president, the economy has gone to hell.
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Arguments do not =
explanations
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Conditional statement(hypothetical) while not;
- an argument it can still be part of one
- compound prop.
- it is false only when the antecedent is true and the consequent is false
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Proposition:
An assertion that something is (or isnt) the case; they are either true or false
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Inductive:
- invalid
- if premises are true doesnt mean conclusion is
- premises only make the conc. LIKELY to true but not absolutely
- *prediction of future is always inductive
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Deductive
- validq
- if premises are true then the con. has to be true
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Four kinds of inductive arguments
- 1. predictions about future
- 2. argument from analogy
- 3. inductive generalization
- 4. causal inferences
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Argument from analogy
the premises indicate how a number of objects are similar and inferences drawn, given that it is reasonable to say they are similar in ways we dont know about and ways we do
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Example of arg. from analogy
- Tom and Hank and Dick all own BMW Z3 2009 built in Greer
- Tom and Dick's cars get 37 miles togallon (we dont know how much Hanks gets but we assmue it is the same)
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Inductive generalization
- The premises give us information about a sample (subset) of some group. The conclusion is that the findinngs of the sample are true for the whole.
- We generalize
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Causal inference
- Has premises that provide that something has happened, the con. provides some causation of the event.
- Causes and effects
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Example of Causal inference
I forgot to put the ice cream up before i went to bed (we infer a certain effect) infer that itmelted. - Maybe someone else put it away...there are alternative accounts forother reasons
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If i intend that my premises are saying the truth for the conclusion, then it is
deductive
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Deductive can only either be;
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Refutation by counter example
- 1. If A, then B
- 2. Not A
- 3. Not B
- If obama were a rockstar he'd be famous
- Obama isnt a fockstar
- Obama isnt famous
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Classical logic
- traditional techniques
- based on aristotles works for the analyses of deductive arguments
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Fallacy
a type of argument that may seem to be correct but contains a mistake in reasoning
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Fallacies of Relevance
fallacies in which the premises are irrelecent to the conclusion
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5 types of fallacies of relevance
- 1. the appeal to emotion
- 2. the appealto pity
- 3. the appealto force
- 4. argument against the person
- 5. irrelevant conclusion
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Appeal to emotion
- Fallacy in which the argument relies on emotion rather than reason.
- ad populum
- boarders on brainwashing
- type of propaganda...bandwagon effect
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Appeal to pity
fallacy in which the arg. relies on gerosity, altruism, or mercy, rather than reason
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Appeal to force
fallacy in which the arg relies on the threat of force; threat may be veiled.
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Argument ad hominem
- fallacy in which the erg. relies on an attack against the person taking a position
- can be abusive or circumstantial
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Irrelevent conclusion
type of fallacy in which the premises support a different con. than the one that is proposed
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Fallacies of presumption
fallacies in which the con. depends on a tacit assumption that is dubious, unwarranted, or false
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Types of presumption fallacies
- 1. fallacy of accident
- 2. complex question
- 3. begging the question
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Fallacy of accident
fallacy in which a generalization is wrongly applied to a particular case
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Complex question
fallacy in which a question is asked in a way that presupposes the truth of some proposition buried within the question
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Begging the question
- fallacy in which the con. is stated or assumed within one of the premises
- also known as circular argument
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Fallacies of ambiguity
fallacies causes by a shift or confusion of meanings within an argument
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types of ambiguity fallacies
- 1. fallacy of equivocation
- 2. fallacy of amphiboly
- 3. fallacy of accent
- 4. fallacy of composition
- 5. fallacy of division
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Fallacy of equivocation
fallacy in which 2 or more meanings of a word or phrase are used in different parts of an argument
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Fallacy of amphiboly
- fallacy in which a loose or awkward combination of words can be interpreted in more than 1 way.
- The premise is based on 1 interpretation while the con. relies on a different interpretation
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Fallacy of accent
fallacy in which a phrase is used to convey 2different meanings within an arg. and the difference is based on changes in emphasis given to words within a phrase
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Fallacy of composition
fallacy in which an inference is mistakenly drawn from the attributes of the parts of a whole, to the attributes of the whole
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Fallacy of division
fallacy in which a mistaken inference is drawn from the attributes of a whole to the attributes of the parts of the whole
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