Task 2 Flashcards
Logic
- Organized body of knowledge or science, that evaluates arguments
- Aim: to develop a system of methods/principles that we use as criteria for evaluating the arguments and to guide our own construction of arguments
- To distinguish good/bad arguments
Argument
-Group of statements (sentence that is either true or false)
truth value
two possible values for one statement (truth,falsity)
inference
- Reasoning process expressed by an argument
- Used interchangeably with ‘argument’
Proposition
-statement (meaning, info content)
2 conditions must be fulfilled for an argument
1) At least one of the statements must claim to present evidence or reasons
2) There must be a claim that the alleged evidence supports/implies smth (a claim that something follows from the alleged evidence/reasons)
noninferential passages (9)
1) warnings
2) piece of advice
3) statement of belief/opinion
4) loosely associated statements
5) reports (careful with reports about arguments!)
6) expository passages
7) illustrations
8) explanations
9) conditional statements
expository passages
- begins with topic sentence followed by one/more sentences that develop the topic sentence
- > try to find out if they try to prove that smth is true
Illustrations
- expression involving one/more examples
- to show what something means /how it is done
- often confused with arguments (uses indicator words such as ‘thus’)
- no claim that anything is being proved
- if claim illustrated is accepted by nearly everyone -> passage is no argument
explanations
- shed light on some event/phenomenon
- event in question is usually accepted as a matter of fact
- 2 components: explanadum (describes event/phenomenon), explanans (explaining)
- explains WHY smth is the case, does not prove THAT smth is the case
conditional statements
- if..(antecedent)…then( consequent)
- no claim to prove anything
- no single conditional statement is an argument , it can serve as premise or conclusion
1) Sufficient condition: A is all that is needed for occurrence of B
2) Necessary condition: Whenever A cannot occur without occurrence of B
Deducutive arguments (5)
- > Impossible for the conclusion to be false given that the premises are true
1) Argument based on mathematics (are all deductive, despite statistics)
2) Argument from definition
3) Categorical syllogism (each statement begins with one of the words ‘all’, ‘no’, or ‘some’)
4) Hypothetical syllogism (conditional statement in one or both premises)
5) Disjunctive syllogism (either..or)
Validity - deductive arguments
- Not determined by actual truth/falsity of premises and conclusion
- Determined by relationship (whether premises support conclusion)
- BUT: any deductive argument having actually true premises and actually false conclusion is invalid!
Valid -> impossible for the conclusion to be false, given the premises are true
Invalid -> possible for conclusion to be false -> conclusion does not follow with strict necessity from premises even though it is claimed to
soundness - deductive arguments
- Sound argument: deductive argument that is valid and has all true premises
- Unsound: invalid and one/more false premises
Inductive argument (6)
- Improbable that the conclusion be false given that the premises are true
1) Prediction (claim about future)
2) Argument from analogy
3) Generalization (use of stats)
4) Argument of authority
5) Argument based on signs (any kind of message (usually visual) produced by any intelligent being)
6) Causal inference (e.g. tasting a piece of chicken and finding it dry and tough, one might conclude that it had been overcooked)
Strength - inductive arguments
-Results not from actual truth/falsity but from probabilistic support the premises give to the conclusion
- Strong: improbable that conclusion is false given that premises are true
- Weak: conclusion does not follow probably from premises
Cogency - inductive arguments
- Cogent: inductive argument that is strong and has all true premises + premises meet the total evidence requirement
- Uncogent: weak/ has one or more false premises, fails to meet total evidence
Counterexample method
- A substitution instance having true premises and a false conclusion
- Used to prove invalidity of any invalid argument
- Cannot prove validity of any valid argument
- Useful to keep in mind terms ‘cats, dogs, mammals, fish and animals’ to use for counterexample
- Only for deductive arguments
extended arguments
-The structure of longer arguments can be disclosed by a diagramming method
4 basic argument patterns:
1) Vertical pattern
2) Horizontal pattern
3) Conjoint premises (premises depend on one another)
4) Multiple conclusion
2 linguistic functions
1) Convey information -> cognitive meaning
2) Express/evoke feelings -> emotive meaning
value claim
claim that smth is good/bad/right/wrong/more important etc.
cognitive meanings can be defective in 2 ways:
1) Vague expression -> allows for borderline cases (e.g. love, happiness, peace, rich, normal, conservative)
2) Ambiguous expression -> more than one clearly distinct meaning in a given context (e.g. light, proper, mad, chest, dank, sound, race etc)
- > Verbal dispute: arise over meaning of language (ambiguity/vagueness)
- > Factual dispute: disagreement about facts
Term
-any word/arrangement of words that may serve as the subject of a statement
- proper names (Napoleon, The United States)
- common names (animal, house, activity, person)
- descriptive phrases ( first president of US, books in my library, blue things)
Non-terms
- verbs, nonsubjective adjectives, adverbs, prepositions, nonsyntactic arrangements of words
- e.g.: dictatorial, runs quickly, above and beyond, cabbages into again the forest, etc.
cognitive meaning of terms
1) intensional meaning/
intension/ connotation: qualities or attributes that the term connotes, sense (e.g. ‘cat’ -> furry, 4 legs, moving in a certain way)
2) extensional meaning/ extension/denotation: consists of the members of the class, reference (e.g. ‘cat’ -> all cats in the universe)
- > intension determines extension
conventional connotation
- attributes that the term commonly calls forth in minds of competent speakers of language
- remains more or less the same from person to person and from time to time
Empty extension
- term that has no class members
- e.g. unicorn, gnome, elf -> empty extension but not empty intension
Increasing intension
- each term in the series connotes more attributes than the one preceding it
- animal, mammal, feline, tiger
Decreasing intension
- each term in the series connotes less attributes than the one preceding it
- tiger, feline, mammal, animal
Increasing Extension
- each term in series denotes a class having more members than term preceding
- tiger, feline, mammal, animal
decreasing extension
- each term in a series denotes a class having less members than the preceding term
- animal, mammal, feline, tiger
Definition
- group of words that assigns meaning to some word or group of words
- definiendum: word/group to be defined
- definiens: does the defining
Stipulative definitions
- assigns meaning to a word for the first time
- coining a new word/giving new meaning to an old word
- usually to replace a more complex expression with a simpler one
- example: ‘tigon’ (lions crossbred with tigers) , secret codes , invention of computers (server, hacker, iPhone, bluetooth)
- cannot provide any new info about the subject matter if the definiendum
Lexical definitions
- report meaning that a word already has in a language
- eliminates ambuiguity
Precising definitions
-reduces vagueness of a word
Theoretical definitions ?
- suggesting a theory that gives a certain characterization to the entities that the term denotes
- neither true/false because they function as proposal to see/interpret some phenomenon in a certain way
Persuasive definitions
- engender (erzeugen) favorable/unfavorable attitude toward what is denoted by the definiendum
- assigning emotionally charged meaning to a word while making it appear that the word really has that meaning in the language in which it is used
- synthesis with stipulative, lexical, theoretical definitions ins possible
- example: ‘Abortion’ means the ruthless murdering of innocent human beings
definitional technique - extensional (denotative) definitions (3)
- assigns meaning to a term by indicating members if the class that the definiendum denotes
- most often used for producing lexical and stipulative definitions
1) demonstrative (ostensive) definitions)
2) enumerative definitions
3) definition by subclass
demonstrative (ostensive) definition - extensional (denotative) definition
- gesture of pointing
- most primitive and most limited
- gesture must count as a word
enumerative definition- extensional (denotative) definition
- naming the members of the class the term denotes
- relatively few classes can be completely enumerated
definition by subclass - extensional (denotative) definition
- naming subclasses
- example: ‘Tree’ means an oak, pine, elm, maple, etc.
-complete definitions by subclass are often difficult/impossible
Intensional (connotative) definitions (4)
-> assigns meaning to a word by indicating the qualities/attributes that the word connotes
1) synonymous definitions
2) etymological definition
3) operational definition
4) definition by genus and difference
synonymous defintion
- The definiens is a single word that connotes the same attributes as the definiendum (syllogism)
- Example: ‘physician’ means doctor
- Only lexical definitions
etymological definition
- Assigns meaning to a word by disclosing the word’s ancestry in both its own language and other languages
- Conveys word’s root meaning/seminal meaning from which all other associated meanings are derived
- One often has access to meaning of an entire constellation of related words
operational definition
- Assigns meaning to a word by specifying certain experimental procedures that determine whether or not the word applies to a certain thing
- > For constructing stipulative, lexical (but no complete) , precising, and persuasive definitions
-E.g. ‘Brain activity’ means that an electroencephalograph shows oscillations when attached to a patient’s head
Problem:
- they usually convey only part of intensional meaning of a term ( brain activity means more than oscillations on an electroencephalograph)
- terms outside of science: no adequate operational definition for ‘love’, ‘respect’, ‘freedom’..
Definition by genus and difference
- Identifying a genus term and one/more difference words, that convey the meaning of the term being defined
- Can be used for lexical, precising, theoretical, and persuasive definitions
- Genus: relatively larger class
- Species: relatively smaller subclass of the genus
- Specific difference: attribute(s) that distinguish the various species with a genus
-E.g. Ice (species) means frozen (difference) water (genus) ; Daughter (species) means female (difference) offspring (genus)
rules for lexical definitions (8)
1) should conform the standards of proper grammar
2) should convey essential meaning of the word being defined
3) should be neither too broad nor too narrow
4) should avoid circularity
5) should not be negative when it can be affirmative
6) should avoid figurative (metaphors), obscure ( defective or inappropriate language/ needlessly technical language), vague, or ambiguous language
7) should avoid affective terminology
8) should indicate the context of the definiens pertains
