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Being Logical D. Q. McInerny

Introduction

Introduction Assignment

 Read the Preface and Part 1 – Preparing the Mind for Logic   Be prepared to discuss what you have read Hint: if you find a list of “things” you may want to make note of these Copyright 2008, Scott Gray 4

Part 1 – Preparing the Mind for Logic

Be Attentive

 Describe a time when your inattentiveness caused a problem   How can you be more attentive?

Are there situations or topics where your attention drifts and it shouldn’t?

 Are their topics or situations where it is usually OK to pay less attention?

Part 1 – Preparing the Mind for Logic

Get the Facts Straight

    What are the two types of facts?

How can you verify facts?

Are “facts” the same thing as “truth”?

Does everyone agree that there are objective facts? Objective truths?

Part 1 – Preparing the Mind for Logic

Ideas and Objects of Ideas

    Are all ideas traceable to extant things? Do these things exist in the world?

What about the idea that 2+2=4? Does this exist in the world? Is existence equivalent to tangible?

Is the author taking about verifiable truth here?

What about the existence of God?

Part 1 – Preparing the Mind for Logic

Ideas and Objects of Ideas

 “An idea is the subjective evocation of an objective fact.” Discuss.

Part 1 – Preparing the Mind for Logic Be Mindful of Origins of Ideas

   Why is objectivity important?

What is wrong when people say they create reality by their ideas?

How does the break between an idea and its object (thing, event) lead to miscommunication?

Part 1 – Preparing the Mind for Logic Match Ideas to Facts

 What are the three components of human knowledge?

  What are simple and complex ideas?

Part 1 – Preparing the Mind for Logic Match Words to Ideas

 Do you agree that ideas are not directly communicable?

  How do you make sure your words convey the idea they represent?

Do words establish reality?

Part 1 – Preparing the Mind for Logic Effective Communication

   How do you know what your audience knows about the meaning of your words?

What is the importance of complete sentences?

What is the difference between a value statement and a factual statement? Are they interchangeable?

Part 1 – Preparing the Mind for Logic Effective Communication

 Are true statements of fact open to argument?

 How do you know the language level of your audience?

Part 1 – Preparing the Mind for Logic

Part 1 – Preparing the Mind for Logic Truth

   Define ontological and logical truth Why is the coherence theory of truth subordinate to the correspondence theory?

How is the coherence theory of truth abused?

Part 1 – Preparing the Mind for Logic Assignments

Part 2 – The Basic Principles of Logic First Principles

 How do the first principles of logic apply to all sciences?

  Explain the principle of identity.

Explain the principle of excluded middle.

 Does this principle apply to things other than existence?

Part 2 – The Basic Principles of Logic First Principles, cont.

 Explain the principle of sufficient reason (causality).

  Should we limit this principle to the physical world?

How does this principle bear on evolution?

Part 2 – The Basic Principles of Logic First Principles, cont.

  Explain the principle of contradiction.

Does this violate the principle of contradiction: Pres. Bush was wrong to invade Iraq, because al Qaeda is not there; we are making al Qaeda mad because we are killing them in Iraq.

Part 2 – The Basic Principles of Logic Gray Areas & Explanations

 Are there really gray areas? Is anything really black & white?

 How should the fact of there being an explanation for everything affect your curiosity?

Part 2 – The Basic Principles of Logic Causes

 Why is it important to find root causes?

  Define efficient cause. What are its sub-divisions?

Define final cause.

  Define material cause.

Define formal cause.

Part 2 – The Basic Principles of Logic Terms

 What are the benefits of defining your terms?

 Why define terms by both generalities (proximate genus) and specifics (specific difference)?

Part 2 – The Basic Principles of Logic The Categorical Statement

   Define a categorical statement.

Why do categorical statements form the best conclusions in logical arguments?

Give an example of a categorical statement form which is not a categorical statement.

Part 2 – The Basic Principles of Logic Generalizations

 Why would someone avoid qualifiers (all, some, etc) in their statements?

  Define universal, particular, and singular statements.

How can you be precise in particular statements?

Part 2 – The Basic Principles of Logic Assignments

Part 3 – Argument: The Language of Logic

Founding an Argument

 What is a premise? What is a conclusion?

 What are the problems with a single argument having multiple conclusions?

Part 3 – Argument: The Language of Logic

Universal to Particular and Back

  Explain why “if something is universally true it is particularly true” is useful in logical thinking?

Is the move from particular to universal necessarily true? What about the other way?

 How can you properly move from particular to universal?

Part 3 – Argument: The Language of Logic

Predication; Negation

    What is the test of sound predication?

How is truth and falsity related to affirmative and negative statements?

Do you agree with the author’s understanding of the mongrel statement on p.53?

What about the neurotic authors on p. 54?

Part 3 – Argument: The Language of Logic

Comparisons

   Comparisons are foundational to thought; judgment is crucial to linking ideas coherently. How does this relate to “being judgmental”?

How does the mice & elephant illustration (p.57) inform your reception of comparisons of unknown (to you) things?

Is argument by analogy a strong argument?

Part 3 – Argument: The Language of Logic

Sound Arguments

   Define a “sound argument”.

What is the difference between truth & validity?

What is the difference between inclusive OR and exclusive OR?

Part 3 – Argument: The Language of Logic

Conditional Arguments

  Why don’t we always have a “real necessary” connection between antecedent and consequent? Should we?

How do we assess conditional arguments in light of this?

 How does the future orientation of conditionals affect their reliability?

Part 3 – Argument: The Language of Logic

Assignment

Part 3 – Argument: The Language of Logic

Syllogistic Argument

  What are the three elements of a categorical syllogism? These elements are called propositions.

We are going to dig into categorical syllogisms more deeply than the book covered them.

 The next cell has a chart showing all possible forms of a proposition.

Part 3 – Argument: The Language of Logic

Categorical Syllogisms: Propositions

Type (or mood) A E I O

Form

All S are P No S are P Some S are P Some S are not

Example

All whales are mammals No whales are fish Some logicians are philosophers Some philosophers are not logicians 34

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Propositions, cont.

  The variables “S” and “P” are placeholders for terms which indicate a class or category of thing. Hence categorical propositions.

In a categorical syllogism there are three terms. Two terms in each premise. A total of two occurrences of each term in the entire argument. There are a total of six occurrences of three terms.

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Propositions, cont.

    The “S” and “P” (the subject and predicate terms) are also known as the “minor” and “major” terms, respectively.

The major term is the predicate of the conclusion and also occurs once in one of the premises, which is known as the major premise.

The minor term is the subject of the conclusion and also occurs once in the other premise, known as the minor premise.

The third term occurs once in each premise, but not in the conclusion, also known as the middle term.

Part 3 – Argument: The Language of Logic

Categorical Syllogisms: Standard Form

   Major premise Minor premise Conclusion Each of these may be one of the four types or moods: A, E, I, or O These moods may be listed in the order they occur in the standard form to identify the syllogism. Examples OAO, EIO Copyright 2008, Scott Gray 37

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Standard Form, cont.

 To uniquely identify the syllogism we also need to know where the middle term occurs in both premises. This is done using a diagram: M P P M M P P M 1 2 3 4 S M S M M S M S Copyright 2008, Scott Gray 38

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Standard Form, cont.

   With the number indication of the location of the middle term we can identify any syllogism: IAI-3 or AEE-4, for example.

How many distinct forms of categorical syllogism are there?

Some syllogistic forms are valid and other are invalid. Every syllogism which uses a valid form is a valid argument, regardless of the contents. The same is true, in the inverted sense, for the invalid forms – the contents don’t matter.

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Standard Form, cont.

 There are only a handful of validating categorical syllogisms   There is not even agreement here, as some commit the Existential Fallacy See http://en.wikipedia.org/wiki/Syllogism a list of the validating forms for Copyright 2008, Scott Gray 40

Part 3 – Argument: The Language of Logic

Categorical Syllogisms: Distribution

     Distributed term: all individual members of the category are accounted for.

“All A are B” – the subject is distributed “No A are B” – both subject & predicate are distributed “Some A are B” – neither subject nor predicate are distributed “Some A are not B” – the predicate is distributed Copyright 2008, Scott Gray 41

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Proposition Types Revisited

Form

All X is Y

Type

Quality

Affirmative

Quantity

Universal

Distribution of X Distribution of Y

Distributed Undistributed No X is

Some X is Y Some X is not Y E I Negative O Negative Universal Affirmative Existential Existential Distributed Distributed Undistributed Undistributed Undistributed Distributed Copyright 2008, Scott Gray 42

Part 3 – Argument: The Language of Logic

Categorical Syllogisms: Examples

     All philosophers are professors.

All philosophers are logicians.

Therefore, all logicians are professors.

What is the form?

AAA-3 Is this a valid syllogism? What about this one: All terriers are dogs.

All terriers are mammals.

Therefore, all mammals are dogs.

Part 3 – Argument: The Language of Logic

Categorical Syllogisms: Diagramming

  Use a Venn diagram.

There are three steps: • draw 3 overlapping circles, label them to represent the major, minor, and middle terms • draw the diagrams of both of the premises  always begin with the universal proposition    in each case, you only touch two circles, never three for the universal & negated universal, fill an area for the existential, mark an “X” • without drawing anything else, look for the drawing of the conclusion; if the syllogism is valid, it is already drawn Copyright 2008, Scott Gray 44

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Diagramming Example    Diagram example: No M are P.

Some M are S.

Therefore, some S are not P.

What is the form?

Part 3 – Argument: The Language of Logic Categorical Syllogisms: Diagramming Example, cont.

Part 3 – Argument: The Language of Logic

Assignments

Part 4 – The Sources of Illogical Thinking

Skepticism

 “The extreme skeptic proclaims baldly that there is no truth” • Where have you heard that before?

Part 4 – The Sources of Illogical Thinking

Agnosticism

 What are the Greek roots of the word “agnostic”?

 How can saying you are agnostic be a cover for laziness or worse?

Part 4 – The Sources of Illogical Thinking

Narrow-Mindedness

Part 4 – The Sources of Illogical Thinking

Emotions

  Consider how you can recognize when your emotions make it hard for you to be reasonable.

“Never appeal directly to people’s emotions.” • Why not?

• Can you give some examples of this being done?

Part 4 – The Sources of Illogical Thinking

Odds & Ends

   An argument is a logical case for or against something. So, why do some have a problem with arguments?

Can one be sincere and still wrong?

Are there limits to common sense?

Part 4 – The Sources of Illogical Thinking

Assignment

   Read Part 5, The Principle Forms of Illogical Thinking, items (fallacies) 1 11.

Be prepared to discuss each fallacy.

Be listening and looking for examples of these fallacies.

Part 5 – The Principle Forms of Illogical Thinking

Denying the Antecedent

Part 5 – The Principle Forms of Illogical Thinking

Denying the Antecedent, cont.

 Example: "…I want to list seventeen summary statements which, if true, provide abundant reason why the reader should reject evolution and accept special creation as his basic world-view. … 14. Belief in evolution is a necessary component of atheism, pantheism, and all other systems that reject the sovereign authority of an omnipotent personal God." Copyright 2008, Scott Gray 55

Part 5 – The Principle Forms of Illogical Thinking 

Denying the Antecedent, cont.

Analysis of example: • x is “necessary component of” y = if y then x • So, the argument is: If atheism/pantheism is true then evolution is true. Atheism/pantheism is false. Therefore, evolution is false.

• Additionally, the first premise isn’t true anyway.

Part 5 – The Principle Forms of Illogical Thinking

Affirming the Consequent

   Explain this What is the corresponding correct mode?

Part 5 – The Principle Forms of Illogical Thinking

Undistributed Middle

    The middle term is not distributed, ie. It doesn’t account for all of its members.

Example: Some dogs are idiots.

Coda is a dog.

Therefore, Coda is an idiot.

This does not prove Coda is an idiot.

Also known as “Guilt by Association” fallacy.

Part 5 – The Principle Forms of Illogical Thinking

Equivocation

   Define this Mark well that equivocation can occur formally, in a syllogism or formal argument, or informally, whenever there are multiple meanings for a term in an discussion.

Part 5 – The Principle Forms of Illogical Thinking

Begging the Question

    Define this.

AKA • Circular Argument • Circulus in Probando • Petitio Principii • Vicious Circle This is an informal fallacy. It is also a validating form of argument (every instance is valid).

The name of this fallacy has been misused and means “raises the question” to many people.

Part 5 – The Principle Forms of Illogical Thinking

False Assumptions

   Explain Assumptions are necessary for us to function intellectually, but they must always be understood as assumptions.

Similarly, theories must be viewed as such, not treated as fact, a la the theory of evolution.

Part 5 – The Principle Forms of Illogical Thinking

The Straw-Man

   Explain This is a dishonest mistake, in that the one doing it is doing it intentionally, it is a deliberate distortion.

This fallacy is committed against believers quite often.

Part 5 – The Principle Forms of Illogical Thinking

Tradition

 There are two ways tradition is abused. Describe them.

 Can you think of examples in the church of this?

Part 5 – The Principle Forms of Illogical Thinking

Two Wrongs != Right

  Explain.

This fallacy can be in appropriately applied though. Consider those against the death penalty.

Part 5 – The Principle Forms of Illogical Thinking

The Democratic Fallacy

Part 5 – The Principle Forms of Illogical Thinking

Ad Hominem

  Define Take a look at the Fallacy Files on this fallacy for sub-fallacies.

Part 5 – The Principle Forms of Illogical Thinking

Assignments

   Finish reading chapter 5, fallacies 12-28. For each, do you agree with the author?

Read the following articles: • Seeing the Unseen, part 1 • How Not to Argue (Part III) • The New Atheists The web site is now up ( http://192.168.1.2/being_logical/index.html

Part 5 – The Principle Forms of Illogical Thinking

Force

  What does it mean to use something other than “the force of reason” in an argument?

What are some of the ways illicit force can be used?

Part 5 – The Principle Forms of Illogical Thinking

Expertise

 When should and when shouldn’t you give weight to an expert’s opinion?

Part 5 – The Principle Forms of Illogical Thinking

Quantifying a Quality

 Discuss the author’s thoughts on qualifying temperature (p.117-118)  Is identifying “quantifying and quality” as a fallacy a fallacy itself?

Part 5 – The Principle Forms of Illogical Thinking

More than the Source

Part 5 – The Principle Forms of Illogical Thinking Analysis, Reductionism, Misclassification    What is the complement to analysis?

What is the fallacy of reductionism?

How/why do we misclassify things?

Part 5 – The Principle Forms of Illogical Thinking

Red Herring

  What is the red herring fallacy?

Part 5 – The Principle Forms of Illogical Thinking

Laughter, Tears and Other Distractions

  Describe these fallacies Does it ever legitimately serve our purpose to make people laugh or sad?

Part 5 – The Principle Forms of Illogical Thinking

Incompetence Fallacy

 Does our inability to prove something mean it is false?

 How does the example on p.124 relate to burden of proof.

Part 5 – The Principle Forms of Illogical Thinking

False Dilemma

   Define the false dilemma.

AKA Excluded Middle, Black-and-White Fallacy Example: "Gerda Reith is convinced that superstition can be a positive force. 'It gives you a sense of control by making you think you can work out what's going to happen next,' she says. 'And it also makes you feel lucky. And to take a risk or to enter into a chancy situation, you really have to believe in your own luck. In that sense, it's a very useful way of thinking, because the alternative is fatalism, which is to say, 'Oh, there's nothing I can do.' At least superstition makes people do things.'" Copyright 2008, Scott Gray 76

Part 5 – The Principle Forms of Illogical Thinking

Post Hoc Ergo Propter Hoc

  Describe this fallacy Sometimes counter-examples help to understand and correct: Roosters crow just before the sun rises. Therefore, roosters crowing cause the sun to rise.

Part 5 – The Principle Forms of Illogical Thinking Special Pleading, Expediency, Avoiding Conclusions, Simplistic Reasoning    The author botches special pleading!

Give an example of the expedient fallacy.

What are some problems with ignoring conclusions?

 Why do you suppose the author left the simplistic reasoning fallacy to the end?

Document

Transcript Document

Being Logical D. Q. McInerny

Introduction

Introduction

Introduction Assignment

Part 1 – Preparing the Mind for Logic

Be Attentive

Part 1 – Preparing the Mind for Logic

Get the Facts Straight

Part 1 – Preparing the Mind for Logic

Ideas and Objects of Ideas

Part 1 – Preparing the Mind for Logic

Ideas and Objects of Ideas

Part 1 – Preparing the Mind for Logic Be Mindful of Origins of Ideas

Part 1 – Preparing the Mind for Logic Match Ideas to Facts

Part 1 – Preparing the Mind for Logic Match Words to Ideas

Part 1 – Preparing the Mind for Logic Effective Communication

Part 1 – Preparing the Mind for Logic Effective Communication

Part 1 – Preparing the Mind for Logic

Part 1 – Preparing the Mind for Logic Truth

Part 1 – Preparing the Mind for Logic Assignments

Part 2 – The Basic Principles of Logic First Principles

Part 2 – The Basic Principles of Logic First Principles, cont.

Part 2 – The Basic Principles of Logic First Principles, cont.

Part 2 – The Basic Principles of Logic Gray Areas & Explanations

Part 2 – The Basic Principles of Logic Causes

Part 2 – The Basic Principles of Logic Terms

Part 2 – The Basic Principles of Logic The Categorical Statement

Part 2 – The Basic Principles of Logic Generalizations

Part 2 – The Basic Principles of Logic Assignments

Founding an Argument

Universal to Particular and Back

Predication; Negation

Comparisons

Sound Arguments

Conditional Arguments

Assignment

Syllogistic Argument

Categorical Syllogisms: Propositions

Categorical Syllogisms: Standard Form

Categorical Syllogisms: Distribution

Categorical Syllogisms: Examples

Categorical Syllogisms: Diagramming

Assignments

Skepticism

Agnosticism

Narrow-Mindedness

Emotions

Odds & Ends

Assignment

Denying the Antecedent

Denying the Antecedent, cont.

Denying the Antecedent, cont.

Affirming the Consequent

Undistributed Middle

Equivocation

Begging the Question

False Assumptions

The Straw-Man

Tradition

Two Wrongs != Right

The Democratic Fallacy

Ad Hominem

Assignments

Force

Expertise

Quantifying a Quality

More than the Source

Red Herring

Laughter, Tears and Other Distractions

Incompetence Fallacy

False Dilemma

Post Hoc Ergo Propter Hoc

Directory