Logic Exam One Definitions
Terms
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- The study of the methods and principles used to distinguish correct form incorrect reasoning
- Logic
- An assertion that something is (or is not) the case; all are either true or false
- Proposition
- The meaning of a declarative sentence at a particular time; in logic, this owrd is sometimes used instead of "proposition"
- Statement
- A proposition making only one assertion
- Simple Proposition
- A proposition containing two or more simple propositions
- Compound Proposition
- A type of compound proposition in which neither of the two components is asserted, using "either/or"; if true, at least one of the component propositions must be true
- Disjunctive (or Alternative) Proposition
- A type of compound proposition that states "if... then"; it is false only when the antecedent is true and the consequent is false
- Hypothetical (or Conditional) Proposition
- A process of linking propositions by affirming one proposition on the basis of one or more other propositions
- Inference
- A structured group of propositions, reflecting an inference; all are either valid or invalid
- Argument
- A proposition used in an argument to support some other proposition
- Premise
- The proposition in an argument that the other propositions, the premises, support
- Conclusion
- Claims to support its conclusion conclusively; one of the two classes of argument
- Deductive Argument
- Claims to support its conclusion only with some degree of probability; one of the two classes of argument
- Inductive Argument
- If all the premises are true, the conclusion must be true; applies only to deductive arguments
- Valid Argument
- The conclusion is not necessarily true, even if all the premises are true; applies only to deductive arguments
- Invalid Argument
- Traditional techniques, based on Aristotle's works, for the analysis of deductive arguments
- Classical Logic
- Methods used by most modern logicians to analyze deductive arguments
- Modern Symbolic Logic
- The likelihood that some conclusion (of an inductive argument) is true
- Probability
- An attribute of a proposition that asserts what really is the case
- Truth
- An argument that is valid and has only true premises
- Sound
- Language used to convey information
- Informative Discourse
- Language used to convey or evoke feelings
- Expressive Discourse
- Language used to cause or prevent action
- Directive Discourse
- A mix of language functions (usually expressive and directive) with special social uses
- Ceremonial Use of Language
- A special form of speech that simultaneously reports on, and performs some function
- Performative Utterance
- A form of genuine dispute that at first appears to be merely verbal
- Criterial Dispute
- The symbol being defined
- Definiendum
- The symbol (or group of symbols) that has the same meaning as the definiendum
- Definiens
- A proposal to arbitrarily assign meaning to a newly introduced symbol; a proposal of a way to use a word, neither true nor false
- Stipulative Definition
- A report -- which may be true or false -- of the meaning a definiendum already has in actual language usage
- Lexical Definition
- A report on existing language usage, with additional stipulations provided to reduce vagueness
- Precising Definition
- Uncertainty because a word or phrase has more than one meaning
- Ambiguity
- Lack of clarity regarding the "borders" of a term's meaning
- Vagueness
- An account of a term that is helpful for general understanding or in scientific practice; open to question, can always be criticized
- Theoretical Definition
- A definition intended to influence attitudes of emotions; often used as a way of making some idea more or less acceptable
- Persuasive Definition
- The collection of objects to which a general term is correctly applied
- Extension
- The attributes shared by all objects, and only those objects, to which a general term applies
- Intension
- As intension increases, the extension decreases or stays the same
- Law of Inverse Variation
- A definition based on the term's extension. This type of definition is usually flawed because it is most often impossible to enumberate all the objects in a general class
- Denotative Definition
- A demonstrative definition; a term is defined by pointing at an object
- Ostensive Definition
- A denotative definition that uses gesture and a descriptive phrase
- Quasi-Ostensive Definition
- What the speaker believes is the intension; the private interpretation of a term at a particular time
- Subjective Intension
- The total set of attributes shared by all the objects in the word's extension
- Objective Intension
- The commonly accepted intension of a term; the public meaning that permits and facilitates communication
- Conventional Intension
- Defining a word with another word that has the same meaning and is already understood
- Synonymous Definition
- Defining a term by limiting its use to situations where certain actions or operations lead to specified results
- Operational Definition
- Defining a term by identifying the larger class of which it is a member, and the distinguishing attributes that characterize it specifically
- Definition by Genus and Difference
- A type of argument that may seem to be correct, but contains a mistake in reasoning
- Fallacy
- Fallacies in which the premises are irrelevant to the conclusion
- Fallacies of Relevance
- A type of ad hominem attack that cuts off rational discourse
- Poisoning the Well
- A type of irrelevant conclusion fallacy in which the opponent's position is misrepresented
- Straw Man Fallacy
- A type of irrelevant conclusion fallacy in which a distracting element is introduced to obscure an opponent's position
- Red Herring Fallacy
- "Does not follow"; often applied to fallacies of relevance, since the conclusion does not follow from the premises
- Non Sequitor
- Fallacies in which the premises are too weark or ineffective to warrant the conclusion
- Fallacies of Defective Induction
- "After the thing, therefore because of the thing"; a type of false cause fallacy in which an event is presumed to have been caused by another event that came before it
- Post Hoc Ergo Propter Hoc
- A type of false cause fallacy in which change in a particular direction is assumed to lead inevitably to further, disastrous, change in the same direction
- Slippery Slope
- Fallaces in which the conclusion depends on a tactic assumption that is dubious, unwarranted, or false
- Fallacies of Presumption
- Fallacies caused by a shift or confusion of meanings within an argument. Also known as sophisms
- Fallacies of Ambiguity