Review Chapter 8 Deductive Reasoning. Deductive Logic Classical: by putting in proper form we will force conclusion – Standard Form – Putting things in.

Review

Chapter 8Deductive Reasoning

Deductive Logic• Classical: by putting in proper form we will

force conclusion– Standard Form– Putting things in classes

• Modern: by showing flow of argument we will force conclusion– Proofs– Mini-valid arguments

Classical Logic, Syllogism• The rule of three: ties argument togetherAll arguments must only have three lines (2 premises and 1 conclusion) and three terms• All lines have subject-predicate relationshipPutting the subject term into a certain class• The Inference- how terms are arranged

– Major term- pred. in conclusion + one premise– Minor term- subject in conclusion + one premise– Middle term- term in both premises, not in concl.

Mood + Figure = Form

Mood

• Each line can only be 1 of 4 mood types– A: All S are P – E: No S are P– I: Some S are P– O: Some S are not P

• Full argument has a 3 letter mood (AIE)• 64 possible mood types

Figure

• Figure is where the middle term is placed

• Mood + Figure = Form• 64 X 4 = 256 possible forms

Form

• Valid forms– 15/256 are valid standard form argumentsSet up in a manner that:

• Forces you to accept the conclusion if both the premises are true

• Sound argument is set up in a valid way and has ALL true statement.

In the end it is the way we set up our argument that allow us to check if it is valid and sound.

Modern Logic

• Doesn’t force us to set up arguments in any way or format– Do need one statement as a conclusion– As many premises as you want

• Proven deductive rules (mini-arguments) can show the flow of logic (reason)– Inference

• These are called proofs– much like geometry• 9 elementary rules/ you need to know 4

Four Rules

Modus Ponens (M.P.)If P then Q

PTherefore Q

Modus Tollens (M.T.)If P then Q

Not QTherefore not P

Hypothetical Syllogism (H.S.)If P then QIf Q then R

Therefore if P then R

Disjunctive Syllogism (D.S.)P or QNot P

Therefore Q

1. I (C v K)2. I3. ~C4. K (~S E)5. M S /Therefore ~M6. C v K (1)(2) MP7. K (6)(3) DS8. ~S E (4)(7) MP9. ~S (8) Simp.10. ~M (5)(9) MT

Language and CommunicationChapter 3

Arguments- Logic

• Argument are only as good as our expression of them– Way you communicate– Language you use– Not one way to express them

• Two way street

• Logic can also….– Help us organize our arguments better– Help us decipher good and bad arguments

Communication is getting your ideas across in a clear & logical manner (choice you make)

Language, meaning & communicating

• Recognize which definition we are discussing– Definition can be subjective– We make the dictionary (we agree on words)

• Clear up “messy” language or definitions– Not universal– Words with multiple meanings and punctuation

Word definitions are built, not given to us & Words change meaning with time & New words come into common vocabulary, old words go away

Language• Symbols that we place meaning on (spelling and grammar)• Need to agree on definition and the value of words used• 4 types of languages

– Informative• Making a statement (true or false)• This is where logic is concerned

– Expressive• Expresses your feelings, use emotional words (Poetry)

– Directive• Influence people’s actions (Get up!)

– Ceremonial• We say these things to be polite or accepted• Greeting: ‘hello’, ‘good morning’, ‘how are you’

• Some statement cross over two or more types

Word Meanings• Denotative meaning (objective)

– Tells us what characteristics and features that we associated with that given word– Dog = tail, four legs, barks, big ears (?)

• Connotative meaning (subjective)– Descriptive definition– Tells us personal experiences with that object– Dog = licks face, loyal, protects me

• Stereotype meaning (necessary)– Loosely defines individuals as a group – Obviously we want to limit, not abuse– Individual things fit into MANY groups

Own Words and CommunicationEvaluating definitions

• Definition has to fit– Not too broad, not too narrow

• Does it include all the denotative attributes to the meaning– Does the abject have all the features. Dog = 4 legs, fur, barks – Is it necessary to add features, change meaning (ex: computers)

• Not circular– Do not use term or word to define itself

• Justice: when someone receives justice

• Definition is clear– Make sure the words being used to define

have clear definitions themselves.– Net: anything reticulated lines at equal distance with intersections of

small narrow space between the intersections

• Avoid emotional language, rhetoric and assumptions

Four styles of communication

• Aggressive: Communicate own needs by controlling

other people with manipulation

• Passive: Communicate to avoid confrontation and put others needs ahead of their own

• Passive-Aggressive: Communicate to avoid direct confrontation but use manipulation to get their needs fulfilled.

• Assertive: Communicate own needs and strive for mutually agreed upon solution. This takes good critical thinking skills

Types of definitions

Meanings we place on words

Stipulative Definitions

• A new definition or a change in an old definition– Laws and technology deal with this all the time

• “Morally straight” – Boy Scouts, 2000• Public Domain and Internet• Copyright and Internet• Facebook and lines of privacy

– These become defined by the court and ultimately the Supreme Court

– Most the time they start off as slang• Mankini• Friending• Beer goggles• These become official when entered into dictionary– common

Lexical Definitions

• Is official dictionary definition• Is it used by enough people to be accepted as a

commonly held definition• Purpose

– Increase our vocabulary to explain new things– Clear ambiguity and meaning

• These definitions are always changing– Marriage (man and woman?)– Lubitorium (gas station)– Cold (weather, people, gambling, sports)

Precising Definition

• Used to clear up words and phrases• We customize dictionary definitions to suit our needs

– Term paper (depends on class/teacher)– Learning disability (depends on expectations)

• Occurs because dictionary definition is too vague• Definitions are made by a group or people who use the

term in their field of study or employment– International Astronomical Union: Pluto planet/dwarf planet (2006)?

– Each company defines: Full time employees?

– Each court defines: Justice to the people?

Persuasive Definitions

• Used to influence others about your point of view– Taxation – “governmental robbery”– Genetic engineering – “playing god”– Politicians- “fat cats”

• More important to convey individual EMOTION and not valued INFORMATION

• Biased in nature– “Here is what I think!”• The truth is usually not important it is getting people

to side with your beliefs.– Offer little or no evidence– Don’t look for other options

Communication = We discuss matters that are not one

sided. You don’t have to agree, but you need to listen and respond to be able to

communicate– It’s a choice

Historically the top three skills1. Communication2. Teamwork3. Commercial Awareness

Rhetorical Devices

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