logic guide 1

Introduction To LogicDiscussion Guide 1

Taken directly from Chapters 1 and 2 of our textbook

Moore and Parker’s Critical Thinking

HUM120Cindy Cruz-Cabrera

Critical Thinking BasicsChapter 1

CRITICAL THINKING

• Consists of the rational evaluation of specific claims, including weighing the arguments for and against them.

• Requires evaluating arguments that support the claims we are considering, and weighing them against those that support alternative or contrary views.

CLAIM

• A belief or opinion

• When you are stating a belief or an opinion, you are making a claim.

• Claims are not self-evident – they are not obviously true or false.

• (according to this source): “statement”, “judgment”, “assertion”, “claim” all mean the same thing

ARGUMENT

• When you present a reason for thinking a claim is true, you are giving an argument.

• Has 2 parts: the premise and the conclusion.

• Thus, an argument makes use of two claims, as the premise and conclusion are both claims.

ARGUMENT or EXPLANATION?

• An argument is different from an explanation.

• Argument: attempts to support or prove a conclusion (using an opinion)

• Explanation: specifies what caused something orhow it works or what it is made out of and so forth.

RECOGNIZING ARGUMENTS

• You need at least two claims.

• The word “therefore” or equivalent must stand, either explicitly or implicitly, before one of them.

• “therefore” is often left unstated. Be on the lookout for it.

• A premise and conclusion may also be left unstated. Be on the alert for them.

THEREFORE (Conclusion Indicators)

• It follows that...

• This shows that...

• Thus...

• Hence...

• Consequently...

• Accordingly...

• So...

• My conclusion is...

Premise Indicators

• Since...

• For...

• Because...

• In view of...

• This is implied by...

• Given...

CONCLUSION

• The supported part of the argument

• When you are stating a belief or an opinion, you are making a claim.

PREMISE

• The supporting part of the argument.

• The premise specifies the reason/s for accepting the conclusion.

ISSUE or QUESTION

• Whenever a claim is called into question, or its truth or falsity becomes the subject of consideration or judgment, an issue or question has been raised.

• In this context, “issue” and “context” are used interchangeably.

• When you think critically about a claim, you call it into question – thus making it an issue.

SUBJECTIVITY

• The idea that one opinion is as good as the next.

• PREFERENCE

• Concepts of beauty, taste, art are examples

• Contradiction Test: If Sarah says “A” and Stanley says “Not-A”, and neither one of them is mistaken, that means the opposed claims are subjective.

Extraneous Considerations

These are considerations that influence our thinking regarding an

argument.

Examples of Extraneous Considerations

• Relationship to the speaker (Mom’s opinion)

• Favorable OR negative opinion about someone or something leads to a positive OR negative judgment of what they say (for example, assessment of expertise based on accent, dress or porma, confidence, PR)


• Rhetoric, or language that has psychological force for enhancing attractiveness or negativity but carries no weight (advertising)

• Emotional association of words is a constant obstacle to an objective and neutral assessment of ideas.

• We must distinguish between the thought and the psychological packaging in which it is given to us.


• Be wary of claims that are accompanied by photographs and other images because images, just like rhetoric, can elicit powerful emotions.

EXERCISES

Clear Thinking, Critical Thinking and Clear Writing

Chapter 2

ARGUMENTATIVE ESSAY

• A good argumentative essay consists of four parts:

• A STATEMENT OF THE ISSUE

• A STATEMENT OF ONE’S POSITION

• ARGUMENTS THAT SUPPORT ONE’S POSITION

• REBUTTALS OF ARGUMENTS THAT SUPPORT CONTRARY POSITIONS

VAGUENESS

• A vague statement is one whose meaning is indistinct, imprecise, or lacks details.

• “Go down the road a ways to the turn and you’ll be there.”

• Politician: “I want to reduce crime, I am for fairness in taxation, and I favor a healthy environment.”

• “Do you love me?” Boyfriend/girlfriend

Working on Vagueness

• While differing degrees of vagueness are natural in different situations, arguments should be clear.

• Precising definitions – definitions that spell out in more detail what is meant by a vague concept.

• “Women can tolerate more stress than men.”

• What to do? Clarify what are meant by “tolerate”, “stress”, and “more”.

VAGUE AND MISLEADING COMPARISONS

• Cut by up to half

• Now 25 percent larger

• Quietest by far

• New and improved

• Now better than ever

• More than 20 percent richer

• These are claims that play on our assumptions but actually need clarification. (45)

Working on VAGUE AND MISLEADING COMPARISONS

• Keep the following questions in mind:

• Is important information missing?

• Is the same standard of comparison being used?

• Are the items comparable?

• Is the comparison expressed an average?

AMBIGUOUS CLAIMS• An ambiguous claim is a sentence that is

subject to more than one interpretation.

• Paul cashed a check.

• Jessica rents her house.

• My work here is finished.

• “Farmer Bill Dies in Senate”

• Horatio plays the trumpet by ear.

• Abortion (49)

• Voluntary acts as selfish acts (50)

THREE TYPES OF AMBIGUITY

• The patient has been depressed ever since she began seeing me in 1983.

• Discharge status: Alive but without permission.

• She has had no rigors or shaking chills, but her husband states she was very hot in bed last night.

• The patient left his white blood cells at another hospital.

• The patient refused an autopsy.

• The patient has no past history of suicides.

• The patient states there is a burning pain in his penis which goes to his feet.

SEMANTIC AMBIGUITY• If a claim is ambiguous because it contains an

ambiguous word or phrase, it is said to be a semantic ambiguity.

• The average pirce of a house in Monterey is $995,000.

• Calhoun always lines up on the right side.

• Jessica is cold.

• I know a little Italian.

• Aunt amy does not use glasses.

Working on Semantic Ambiguity

• Semantic ambiguity can be eliminated by substituting an unambiguous word or phrase.

• The average pirce of a house in Monterey is $995,000.

• Calhoun always lines up on the right side.

• Jessica is cold.

• I know a little Italian.

• Aunt amy does not use glasses.

SYNTACTIC AMBIGUITY

• When a statement is ambiguous because of its grammar or the way it has been structured, or put together, it is said to be a syntactic ambiguity.

• The way to eliminate syntactic ambiguity is to alter punctuation or rewrite the claims.

Working on Syntactic Ambiguity• Players with beginners’ skills only may use court

1.

• Susan saw the farmer with binoculars.

• People who protest often get arrested.

• He chased the girl in his car.

• I shot the elephant in my pajamas.

• There’s somebody in the bed next to me.

• The boys chased the girls, and they giggled a lot.

• After he removed the trash from the pool, the children played in it.

• He brushed his teeth on the carpet.

GROUPING AMBIGUITY

• “Secretaries make more money than physicians.”

• Individually or collectively?

• “Lawnmowers create more air pollution than dirt bikes.”

• Bill Clinton and “the biggest tax increase in history”

The Fallacies of Composition and Division

• Fallacy of Division: what is true of a group of things taken collectively or as a group is automatically true of the same things taken individually.

• Fallacy of Composition: what holds for a group of things individually doesn’t automatically hold for the things collectively or as a group.

• (fallacy – mistake in reasoning)

DEFINING TERMS

REASONS TO DEFINE TERMS

• Any serious attempt to think critically about a claim requires having a clear idea of what the claim actually is.

• If there are unfamiliar or unusual words in it, you need to know what they mean.

• If there are familiar words used in an unfamiliar way, you need to know what they mean.

• Most important is to reduce vagueness or eliminate ambiguity. (Ceedee)

Two Main Purposes of Definitions

Stipulating Definition

• Others may use terms we don’t understand, and we may use terms they don’t understand. Onemay even use terms one doesn’t fully understand oneself. In all three cases, the meaning of the term needs to be spelled out. Definitions used for this purpose often are called stipulating definitions.

• A stipulating definition is called for if an unusual or unfamiliar word is used, or if a brand new word is coined, or if a familiar word is being used in a new way.

Precising Definitions

• Sometimes you need to reduce vagueness or eliminate ambiguity; you need to make things more precise. Definitions used for this purpose are called precising definitions.

TYPES OF DEFINITIONS

What counts in the real world of critical thiniking is clarifying a term by whatever method works, including combinations.

DEFINITION BY EXAMPLE

• Pointing to, naming, or describing one or more examples of something to which the defined term applices.

• “By ‘scripture’, I mean books like the Bible or the Koran.”

• “By ‘temperate climate’, I mean weather in an area like the mid-Atlantic states.”

• “A mouse is this thing here, see?”

DEFINITION BY SYNONYM

• Giving another word or phrase that means the same thing.

• “fastidious” means the same as “fussy”

• “Prating” is the same as “chattering”

ANALYTICAL DEFINITION

• Specifying 1) the type of thing the term applies to and 2) the difference between the things the term applies to and other things of the same type.

• “A mongoose is a ferret-sized mammal native to India that eats snakes and is related to civets.”

• A mouse is a piece of computer equipment used to place the position of a cursor.”

RHETORICAL DEFINITION


• “A conservative is a hide-bound, narrow-minded hypocrite who thinks the point to life is to make money and rip off poor people.”

• While this is an analytic definition, this definition wasn’t offered to clarify the meaning of conservative.

• If the purpose is to express or influence attitudes rather than to clarify, it is called a rhetorical definition.


• When people use a “definition” to express their own attitude about something or to manipulate someone else’s attitude, they invariably utilize the rhetorical force of the words in a definition.

• If a definition utilizes words with strong positive or negative associations, we can be pretty sure it is a rhetorical definition, not a definition intended to clarify meaning.

• The use of emotionally charged vs. Neutral terminology

Writing Argumentative Essays

Writing an argumentative essay is doing nothing other than thinking

critically.

Four Components

• A STATEMENT OF THE ISSUE

• A STATEMENT OF ONE’S POSITION

• ARGUMENTS THAT SUPPORT ONE’S POSITION

• REBUTTALS OF ARGUMENTS THAT SUPPORT CONTRARY POSITIONS

Principles of Organization and Focus

Focus

• Make clear at the outset what issue you intend to address and what your position on the issue will be.

Stick to the issue

• All points you make in an essay should be connected to the issue under discussion and should always either 1) support, illustrate, explain, clarify, elaborate on, or emphasize your position onthe issue, or 2) serve as responses to anticipated objections.

• Rid the essay of irrelevancies and dangling thoughts.

Arrange the components of the essay in a logical sequence

• Make a point before you clarify it, for example, and not the other way arround.

• Place support item B next to item B, not next to item F or G.

• “We should go ahead with the picnic; after all, we went to a lot of trouble. Plus, it isn’t going to rain.”

• “We should go ahead with the picnic. Plus, it isn’t going to rain; after all, we went to a lot of trouble.”

Be complete.• Accomplish what you set out to accomplish,

support your position adequately, and anticipate and respond to possible objections.

• Keep in mind that many issues are too large to be treated exhaustively in a single essay. The key to being complete is to define the issue sharply enough that you can be complete. Thus, the more limited your topic, the easier it is to be complete in covering it.

• Be sure there is closure at every level. The essay should reach a conclusion. Reaching a conclusion and summarizing are not the same thing.

Persuasive Writing

• Confine your discussion of an oppoinent’s point of view to issues rather than personal considerations.

• When rebutting an opposing viewpoint, avoid being strident or insulting. Don’t call opposing arguments absurd or ridiculous.

• If an opponent’s argument is good, concede that it is good.

• If space or time is limited, be sure to concentrate on the most important considerations. Don’t become obsessive about rebutting every last criticism of your position.

• Present your strongest argument first.

Reference

• Chapters 1 and 2 of Critical Thinking by Brooke Noel Moore and Richard Parker

logic guide 1

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