Challenge B Introductory Logic Vocabulary Flashcards
Logic
the science and art of reasoning well
Law of Identity
if a statement is true, then it is true
Law of Excluded Middle
any statement is either true or false
Law of Non-Contradiction
a statement can not be both true and false
Formal Logic
branch of logic which deals with the proper modes of reasoning
Informal Logic
branch of logic which deals with operations of thinking that are indirectly related to reasoning
Induction
reasoning with probability from examples or experience to general rules
Deduction
reasoning with certainty from premises to conclusions
Categorical Logic
connects one category (or term) with another (uses syllogisms)
Propositional Logic
connects entire propositions together in arguments
Term
a concept that can be expressed preciselyD
Definition
a statement that gives the meaning of a term
6 Purposes of Definitions
- show relationships
- remove ambiguity
- reduce vagueness
- increase vocabulary
- explain concepts theoretically
- influence attitudes
Ambiguous Word
a word having more than one possible meaning
Lexical Definition
definition which shows relationships or reduces ambiguity by providing a single, established meaning of a term (dictionary definition)
Vague Word
word whose extent is unclear
Precising Definition
definition which makes more precise what was vague or fuzzy applies only to the situation in which it is used)
Stipulative Definition
definition needed when a new word is invented or an existing word is applied in a new way
Theoretical Definition
definition given for a term , not when the word in unfamiliar, but when the term is not understood (often scientific or philosophical in nature)
Persuasive Definition
definition that aims at persuading the listener one way or another toward the term being defined
Genus
a term that is more general, broad, or abstract than the original term and includes it
Species
them that is more specific, narrow, or concrete than the original term and is included by it (a type, kind or example of them)
Mutually Exclusive
not overlapping
Exhaustive
complete, no other types exist
3 Basic Errors to Avoid in Genus-Species Charts
- overlapping species (by changing the dividing principle or by placing a term at the wrong level)
- changing definitions for an ambiguous term
- using parts of the term (should be kinds)
Extension
the sum of all the individual objects described by a term (how broad is a term?)
Intension
the sum of all the common attributes denoted by the term (how narrow/specific is the term?)
3 Methods of Defining Terms
- synonym
- example
- genus-difference
Defining by Synonym
Giving another word with the same meaning (problem if the meaning of the synonym is not known or no synonym exists)
Defining by Example
demonstrating the term; giving several and various examples; listing species of the term (problem because of ambiguity of this method)
Defining by Genus and Difference
naming the genus and then adding descriptive words which distinguish that term from all other species under that genus (IE., what group is it in? What makes it different from everything else in the group?)
Statement
a sentence which is either true or false
3 Types of Sentences that are not statements
- question
- command
- nonsense
Self-Supporting Statements
a statement whose truth value can be determined from the statement itself
3 Types of Self-Supporting Statements
- self-reports
- true or false by logical structure
- true or false by definition
Self-Report
a statement by a person concerning his own desires, beliefs or feelings
True or False by Logical Structure
a statement which can be seen to be true or false by how the sentence is put together
Tautology
a statement which is always TRUE because of its logical structure (Jesus is God or Jesus is not God)
Self-Contradiction
a statement which is always FALSE because of its logical structure (Jesus is God and Jesus is not God)
True of False by Definition
a statement which is necessarily true or false because of the definitions of the words in the sentence
Supported Statement
a statement whose truth value depends on evidence or information from outside itself
3 Ways to Determine the Truth value of Supported Statements
- authority
- experience
- deduction
Authority
a trustworthy, authoritative source (scripture, encyclopedia)
Experience
trusting our own senses to determine truth value
Deduction
reasoning to some conclusion based on other statements, whose truth value we know
4 Relationships Between Statements
- consistency/ inconsistency
- implication
- logical equivalence
- independence
Consistency (Consistent)
when 2 statements CAN both be true at the same time
Inconsistency (Inconsistent)
when there is a conflict between 2 statements so they cannot both be true at the same time
Implication
when the truth of 1 statement REQUIRES the truth of another
Logical Equivalence
when 2 statements IMPLY EACHOTHER ( the statements must both be true or both be false)
Independence
when the truth or falsity of 1 statements has NO EFFECT on the truth or falsity of the other statement
3 Kinds of Disagreements
- real
- apparent
- verbal
Real Disagreement
an actual inconsistency between 2 statements; they cannot both be true at t he same time (Jesus is God. Jesus is not God)
Apparent Disagreement
a difference of opinion or perception (Ann: I think Logic is easy; Bob: I think Logic is hard.)
Verbal Disagreement
a misunderstanding due to differing definitions for one or more words
