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Social Sciences and Humanities

SSH 105

Klaas Kraay

Summer

Description

Chapter 1
Key Concepts
Statement (Claim)
An assertion that something is or is not the case.
Premise
A premise is a statement offering support for a conclusion.
Conclusion
A conclusion is a statement that is held to be supported by a premise or premises.
Inference
The process of reasoning and moving from a premise to a conclusion based on those premises.
Argument
An argument is a set of statements one of which ( conclusion) is taken to be supported by the remaining
statements( premises). Arguments
1. Deductive Arguments:
Deductive argument is to provide logically conclusive support for the conclusion based on the premises.
2. Inductive Arguments:
An inductive argument is when the premises are intended to give probable and not conclusive support for a
conclusion.
Deductive Arguments
1. Invalid Argument:
A True conclusion is not guaranteed with both premises being True, or a False conclusion is the result of one
True premise and one False premise.
Example:
Premise # 1 is True Premise #1 is True
Premise #2 is True Premise #2 is False
Conclusion is False Conclusion is False
2. Valid Argument:
If the premises are True, then the conclusion is guaranteed to be True.
Doesn‟t have to have True Premises and it doesn‟t have to have True conclusion.
3. Sound Argument:
An argument is sound if it is valid and the premises are true.
4. Unsound Argument:
An argument is unsound when it is invalid and not all the premises are True.
Example:
Valid and Sound Argument Unsound Argument
Premise # 1 is True Premise #1 is False
Premise #2 is True Premise #2 is False
Conclusion is True Conclusion is True Inductive Arguments
1. Inductively Strong Argument:
An argument is inductively strong, if and only if the conclusion is probably True given the premises.
Example:
Inductively Strong Argument
Premise # 1 is True 1) Quitting smoking improves health.
Premise #2 is True 2) Mary has quit smoking.
Conclusion is Likely 3) Therefore, Mary‟s health will improve.
2. Inductively Cogent Argument:
An argument is Cogent, if and only if it is Inductively strong and all its premises are in fact True.
An argument can fail to be Cogent in three ways:
1) Not inductively strong.
2) Not all premises are True
3) It is both neither inductively strong and its premises are not True.
3. Inductively Weak Argument:
An argument is inductively weak when, if and only if it is not inductively strong.
Example:
Inductively Weak Argument
Premise #1 is True 1) Few police officers are corrupt.
Premise #2 is True 2) Jim is a Police officer.
Conclusion is Unlikely 3) Therefore, Jim is corrupt. Chapter 2
Knowledge:
Different use of “knowledge”:
1) Knowledge by acquaintance
2) Knowledge – How
3) Propositional Knowledge
Propositional Knowledge:
1) Beliefs
2) Truth Value
3) Justification
The three ingredients to propositional knowledge are belief in the view you hold, truth value and justification
behind it. The aspect of belief and truth go together as you cannot believe something and not hold it to be true.
You cannot say that something has truth to it and not believe in its existence. To have knowledge you must
also justify and state the reasoning behind you acceptance in a certain belief.
Impediments to Critical Thinking : Views about Truth
1. Nihilism:
Nihilism holds the view that there simply are no truths. There is no way for one to be correct or incorrect. The
right answer does not exist therefore moral assertions are neither true nor false.
2. Realism:
Realism states that there are indeed Truths and these are independent from the beliefs of individuals and these
truths are objective. One can be right or wrong but that doesn‟t change the fact that there is an answer.
3. Relativism:
There are truths that exist but they are dependent on us as individuals and what we believe.
a) Social Relativism: The view that truth is relative to societies and large groups.
b) Subjective Relativism: The idea of truth depends on what someone believes.
4. Philosophical Skepticism:
Philosophical Skepticism requires complete certainty since it is based on doubting reality and believes that
data can be manipulated. Chapter 3
Conditional Statements
A conditional statement is a statement of the form
If P, then Q
Example: If it rains, then the picnic will be cancelled.
Conditionals are compound statements composed of two Parts:
The Antecedent – What follows the word “if”
The consequent – What follows the word “then”
Disjunctive Statements
A disjunctive statement is of the form
Either P or Q
Example: Either it rained or the picnic was cancelled.
Disjunctions are compound statements composed if two parts called the disjuncts.
Valid Conditional Argument Invalid Conditional Argument
1. Affirming the Antecedent(Modus Ponens)
If P,then Q
P
Therefore Q 1. Denying the Antecedent
If P,then Q
Not P
2. Denying the Consequent(Modus Tollens) Therefore Not Q
If P,then Q
Not Q
Therefore Not P
3. Hypothetical Syllogism
If P,then Q
If Q,then R
Therefore If P,then R 2. Affirming the Consequent
If P,then Q
Q
4. Disjunctive Syllogism Therefore Not P
Either P or Q
Not P
Therefore Not Q Valid Conditional Argument
Affirming the Antecedent (Modus Ponens)
1) If Ryerson is a great University, then many students apply here.
2) Ryerson is a Great University.
3) Therefore Many Students apply there.
Denying the Consequent (Modus Tollens)
1) If Jim committed the murder, he used his gun on Tuesday.
2) Jim did not use his gun on Tuesday.
3) Therefore Jim did not commit the Murder.
Hypothetical Syllogism
1) If Mitt Romney loses the election, Barack Obama wins.
2) If Barack Obama wins, Michelle Obama will be happy.
3) Therefore if Mitt Romney loses the election, Michelle Obama will be happy.
Disjunctive Syllogism
1) Either the Liberals won the election or the conservatives did.
2) The liberals did not win the election.
3) Therefore the conservatives did.
Invalid Conditional Arguments
Denying the Antecedent
1) If Einstein invented the computer, then he is a genius.
2) Einstein did not invent the computer.
3) Therefore Einstein is not a genius
Affirming the Consequent
1) If Einstein invented the computer, then he is a genius.
2) Einstein is a genius.
3) Therefore Einstein invented the computer. Diagramming Arguments :
Step 1: Mark all the indicator words
Step 2: Number all the assertions in the argument in order of appearance
Step 3: Identify the main conclusion of the argument
Step 4: Identify the premises that directly support the conclusion
Step 5: Decide whether these are dependent or independent premises
Dependent Premises: depend on each other to provide support for the conclusion. A dependent premise, by
itself, does not support the conclusion
Independent Premises: these offer support for the conclusion without the help of any other premises.
Step 6: Draw a diagram for these premises and the main conclusion
Two Ways to figure out of premises are dependent:
(1) The Words Test: if some important words/ideas in the conclusion only occur in one premise and other
important words/ideas from the conclusion only occur in the other premise, then the premises are
probably dependent.
Aristotle is a man, and all men are mortal, so Aristotle is mortal.
(2) The False/Absent Premise Test: if a premise would provide some reason to accept the conclusion even
if the other premise(s) were false (or not present), then the premises are probably independent.
Bill robbed the bank and shot the guard. Bill is obviously a criminal. Chapter 4
Justification
Some Ways our Claims Can be Justified And/or Acceptable:
a) It is true by definition.
b) It is an item of background information.
c) It is supported by personal experience- includes beliefs based on our senses, our memory and our intellect.
d) It is supported by testimony : such as (1) Experts A form of testim

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