Ling 21: Ling 21: LANGUAGE & THOUGHTLANGUAGE & THOUGHT

Lecture 2: Lecture 2:

Recognizing Arguments

ARGUMENT STRUCTUREARGUMENT STRUCTURE

Logic:Logic: The study of arguments The study of arguments

An An argumentargument is a sequence of is a sequence of statements – statements – – One is the One is the conclusionconclusion to the others. to the others.– All the others are All the others are premises.premises.

The premises provide The premises provide evidenceevidence for the for the conclusion.conclusion.

EXAMPLESEXAMPLES

All humans are mortal.All humans are mortal.

Brad Pitt is human.Brad Pitt is human.

Ergo, Brad Pitt is mortal.Ergo, Brad Pitt is mortal.

Sarah was not at the party.Sarah was not at the party.

Ergo, it couldn’t have been Sarah that Ergo, it couldn’t have been Sarah that Jack was dancing with.Jack was dancing with.

FORMAL vs INFORMAL LOGICFORMAL vs INFORMAL LOGIC Formal logic:Formal logic: the study of the study of argument formsargument forms – –

abstract patterns common to many different abstract patterns common to many different arguments.arguments.

validvalid invalidinvalidIf P, then QIf P, then Q If P, then Q If P, then QPP Q QErgo, QErgo, Q Ergo, P Ergo, P

Informal logic:Informal logic: the study of the study of particular particular argumentsarguments in natural language in natural language

PREMISESPREMISES

Premises and conclusions are always Premises and conclusions are always propositionspropositions (statements) – they can (statements) – they can be true or false.be true or false.

They are They are notnot questions, commands or questions, commands or exclamations.exclamations.– Test:Test: “It is true / not true that P” “It is true / not true that P”

where P = a premise or a conclusionwhere P = a premise or a conclusion

EXAMPLEEXAMPLE

It is true that It is true that Sarah was not at the partySarah was not at the party..

**It is true that It is true that Where was SarahWhere was Sarah??

**It is true that It is true that Don’t you dare do that Don’t you dare do that againagain!!

Note:Note: /*/ indicates that a statement is unacceptable. /*/ indicates that a statement is unacceptable.

Exercise:Exercise: Identifying statements. (ex. 2.1, p. Identifying statements. (ex. 2.1, p. 33)33)

NOTE 1NOTE 1At issue is the At issue is the formform of the statement, of the statement, whether it CAN be true or false,whether it CAN be true or false,notnot whether it IS true of false. whether it IS true of false.

These are PROPOSITIONS:These are PROPOSITIONS:Snow is green.Snow is green.I am Brad Pitt.I am Brad Pitt.

These are NOT:These are NOT:*What color is snow?*What color is snow?*Hey, look, there’s Brad Pitt!*Hey, look, there’s Brad Pitt!

NOTE 2NOTE 2

Although the premises, by definition, Although the premises, by definition, provide evidence for the conclusion, provide evidence for the conclusion, this evidence may be good or not.this evidence may be good or not.

You have to let me go to the You have to let me go to the party;party;

everyone is going to be there.everyone is going to be there.

NOTE 3NOTE 3 In standard form, the conclusion appears at In standard form, the conclusion appears at

the the end.end. In practice, the conclusion may appear In practice, the conclusion may appear

anywhereanywhere..

Jack could not have been the murderer.Jack could not have been the murderer.

The victim was shot from 40 feet away.The victim was shot from 40 feet away.

Jack is blind and paralyzed from the Jack is blind and paralyzed from the neck neck down.down.

Exercise:Exercise: Identify premises and conclusions of Identify premises and conclusions of arguments. (ex. 2.2.1, p. 37)arguments. (ex. 2.2.1, p. 37)

CONCLUSIONS INDICATORESCONCLUSIONS INDICATORESInference indicators:Inference indicators: Indicate the Indicate the rolerole of a of a

proposition in an argument.proposition in an argument.Conclusion indicators:Conclusion indicators:

There are no lights on. _____ no one is home.There are no lights on. _____ no one is home.ThereforeThereforeThusThusHenceHenceSoSoFor this reasonFor this reasonConsequentlyConsequentlyIt follows thatIt follows thatWhich proves/means thatWhich proves/means thatAS a resultAS a result

PREMISE INDICATORSPREMISE INDICATORSPremise indicators:Premise indicators:

____ there are no lights on, no one is ____ there are no lights on, no one is home.home.

SinceSince

BecauseBecause

Assuming thatAssuming that

Seeing thatSeeing that

Granted thatGranted that

In view of the fact thatIn view of the fact that

Inasmuch as Inasmuch as

CAUTIONCAUTIONConclusion and premise indicators Conclusion and premise indicators don’t don’t

alwaysalways indicate conclusions and premises: indicate conclusions and premises:

*It has been ages *It has been ages sincesince I ate really good I ate really good sushi.sushi.

*She’s *She’s soso cute! cute!

Exercise:Exercise:

Identify premise/conclusion indicators.Identify premise/conclusion indicators.

(ex. 2.2.2, p. 37)(ex. 2.2.2, p. 37)

IMPLICIT STATEMENTSIMPLICIT STATEMENTSSometimes arguments are not actually Sometimes arguments are not actually

expressed or may be expressed expressed or may be expressed incompletely.incompletely.

One of us will be cleaning the bird cage, and One of us will be cleaning the bird cage, and it won’t be me.it won’t be me.

Implicit conclusionImplicit conclusion: You will be cleaning the : You will be cleaning the bird cage.bird cage.

Alisha wears Birkenstocks, which proves that Alisha wears Birkenstocks, which proves that you don’t have to be a tree-hugger to wear you don’t have to be a tree-hugger to wear Birkenstocks.Birkenstocks.

Implicit premise:Implicit premise: Alisha is not a tree-hugger. Alisha is not a tree-hugger.

IMPLICIT ARGUMENTSIMPLICIT ARGUMENTS Rules governing reading propositions Rules governing reading propositions

into an argumentinto an argument– Do so Do so onlyonly if it is required to complete the if it is required to complete the

arguer’s thought.arguer’s thought.– Do so Do so onlyonly if the arguer would accept the if the arguer would accept the

proposition.proposition.– Employ the Employ the principle of charityprinciple of charity – give the – give the

arguer the benefit of the doubt and make arguer the benefit of the doubt and make the argument as strong as possible.the argument as strong as possible.

– Minimize misrepresentation.Minimize misrepresentation.

NON-ARGUMENTSNON-ARGUMENTS

1.1. ReportsReports

2.2. Unsupported AssertionsUnsupported Assertions

3.3. Conditional StatementsConditional Statements

4.4. IllustrationsIllustrations

5.5. ExplanationsExplanations

REPORTS, ASSERTIONSREPORTS, ASSERTIONS

ReportsReports convey information convey information

Unsupported assertionsUnsupported assertions are are statements of what a speaker or writer statements of what a speaker or writer happens to believe.happens to believe.

CONDITIONAL STATEMENTSCONDITIONAL STATEMENTS Conditional statementsConditional statements ( (if-thenif-then statements) statements)

– Antecedent and consequent sometimes Antecedent and consequent sometimes implicit:implicit:

Should it rain, the picnic will be Should it rain, the picnic will be cancelled.cancelled.Pete will graduate provided he passes Pete will graduate provided he passes calculus.calculus.

– May be parts of argumentsMay be parts of argumentsbut are not themselves arguments.but are not themselves arguments.

ILLUSTRATIONSILLUSTRATIONS Illustrations:Illustrations: provide examplesprovide examples of a claim of a claim

but do but do notnot prove or support it. prove or support it.Many wildflowers are edible.Many wildflowers are edible.For example, daisies and day lilies are For example, daisies and day lilies are delicious in salads.delicious in salads.

There are There are borderline casesborderline cases between between examples and evidence.examples and evidence.

Many of the world’s greatest Many of the world’s greatest musicians musicians died at 27. for example, Jim died at 27. for example, Jim Morrison,Morrison,

Janis Joplin, Jimi Hendrix and Curt Cobain.Janis Joplin, Jimi Hendrix and Curt Cobain.

EXPLANATIONSEXPLANATIONSExplanations:Explanations: try to show try to show why something is why something is

the casethe case, , notnot to prove that to prove that it is the caseit is the case..

The Titanic sank because it hit an iceberg.The Titanic sank because it hit an iceberg.

(Explanation)(Explanation)

Capital punishment should be abolished Capital punishment should be abolished because innocent people may be because innocent people may be mistakenly executed.mistakenly executed. (Argument) (Argument)

EXPLANATIONS – 4 TESTSEXPLANATIONS – 4 TESTS

1.1. The common knowledge testThe common knowledge test

2.2. The past-event testThe past-event test

3.3. The author’s intent testThe author’s intent test

4.4. The Principle of Charity testThe Principle of Charity test

COMMON KNOWLEDGE TESTCOMMON KNOWLEDGE TEST

Is the Is the explanandumexplanandum (what is being (what is being explained) a matter of common explained) a matter of common knowledge?knowledge?

(Why would you try to prove something (Why would you try to prove something that is widely accepted as fact?)that is widely accepted as fact?)

Many musicians die young because they Many musicians die young because they ‘live hard.’‘live hard.’

PAST EVENT TESTPAST EVENT TEST

Is the explanandum an event that Is the explanandum an event that occurred in the past?occurred in the past?

Mel flunked because he never Mel flunked because he never went to class.went to class.

AUTHOR’S INTENT TESTAUTHOR’S INTENT TEST

Is the author trying …Is the author trying …

– To To provide evidence for accepting the provide evidence for accepting the claimclaim as true as true

oror– To To offer an account of why an event offer an account of why an event

occurredoccurred or why something is as it is? or why something is as it is?

Kevin is majoring in PoliSci because Kevin is majoring in PoliSci because he wants to go to law school.he wants to go to law school.

PRINCIPLE OF CHARITY TESTPRINCIPLE OF CHARITY TEST

The The Principle of CharityPrinciple of Charity requires that we requires that we interpret unclear passages generouslyinterpret unclear passages generously..

Here that means not interpreting a Here that means not interpreting a passage as a bad argument when it passage as a bad argument when it would be reasonable to interpret it as would be reasonable to interpret it as a good explanation.a good explanation.

CAUTIONCAUTION

Not foolproof.Not foolproof.

No single shooter could have shot as No single shooter could have shot as quickly and as accurately as Oswald is quickly and as accurately as Oswald is alleged to have done in the Kennedy alleged to have done in the Kennedy assassination. Therefore Oswald was not assassination. Therefore Oswald was not the lone shooterthe lone shooter..

Exercise:Exercise: Identify arguments and Identify arguments and explanations (ex. 2.4.1, p. 48)explanations (ex. 2.4.1, p. 48)