Philosophy 6: Logic in Practice

Los Angeles Pierce College

Department of History, Philosophy, & Sociology

 

 

 

 

 

Lecture Notes

 

 

 

 

 

 

Lecture Notes for "Chapter Four" of Porter's The Voice of Reason

 

 

 

 

 

        

Part One: Disagreements  

 

Types of Disagreement:  Factual and Verbal

 

Understand that we are here engaged in argument identification

 

First step, isolate disagreements

 

With disagreement isolated, we know what we must support

        

 

 

 

 

 

 

 

 

 

        

Types of Disagreement:  Factual and Verbal

 

 

Is!/Is Not!

 

vs.

 

Potato/Potato

        

 

 

 

 

 

 

 

 

 

        

Factual Disagreement       

 

What is the case? 

 

What is not the case? 

        

 

 

 

 

 

 

 

 

 

 

 

Factual Disagreement E.G.s       

 

The number of civilian deaths since the beginning of the second Iraq war is at least 99,712

 

No, others say it surpassed 500,000

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

        

Resolution        

 

Objective evidence is needed to support claims about facts

 

Credible authorities can supply such facts

 

 

 

 

 

 

 

 

 

 

 

Difficulties w/ Resolution        

 

But when evidence is hard to find, resolution can be elusive

 

 

 

 

 

 

 

 

 

 

        

Difficulties w/ Resolution E.G.   

 

Global warming

 

 

 

 

 

 

 

 

 

 

        

Verbal Disagreements       

"A verbal disagreement is another kind of dispute, involving a difference of opinion over what crucial words mean" 

 

        

 

 

 

 

 

 

 

 

 

 

Verbal Disagreements

E.G.s "You're such a drug addict!" 

 

"You smell like a ____." 

        

 

 

 

 

 

 

 

 

 

Some Causes of Verbal Disagreement        

 

"People may have been taught to use a word differently so that the intensional meaning is unusual, or nonnative speakers may have a different extension for the word in their own language" 

 

 

 

 

 

 

 

 

 

 

 

 

        

Resolving Verbal Disagreements        

 

Define your terms! 

 

"We must keep in mind the various types of definitions, whether stipulative, reportive, synonym, or example, and use the one appropriate to our subject"

        

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Interpretive and Evaluative Disagreements        

 

Deeper problems lurk here

        

 

 

 

 

 

 

 

 

 

Interpretive Disagreements      

"Interpretive disagreements do not concern words but are disputes about how events or actions should be construed, how stories, art, speeches, historical episodes, and so forth should be taken"

 

 

 

 

 

 

 

 

        

Interpretive Disagreements E.G.        

 

"To take an everyday example, suppose that someone you know passes by without saying hello.  Should you interpret this as a deliberative snub, that the person 'cut you dead,' or should you assume the person was preoccupied, 'absent-minded?'" 

        

 

 

 

 

 

 

 

 

 

 

 

 

Causes of Interpretive Disagreements       

 

Particular points of view

 

Differing perspectives

        

 

 

 

 

 

 

 

 

 

 

Resolving Interpretive Disagreements       

 

"In trying to find the best interpretation of these events, the stand we should us is plausibility.  That is, we have to build a case showing that a particular interpretation best explains a situation"

        

 

 

 

 

 

 

 

 

 

Differing Interpretations   

 

Seemingly equally good, but mutually exclusive interpretations

 

They can't both be true (usually)

 

 

 

 

 

 

 

 

        

Problems w/ Resolving Interpretive Disagreements  

In persuasive arguments, interpretational vagueness can be intentional

        

 

 

 

 

 

 

 

Evaluative Disagreements

Evaluative disagreements stem from disputants who differ in their "claiming that something should be considered good or bad"

        

 

 

 

 

 

 

 

 

 

 

 

 

 

Evaluative Disagreements

E.G.s The consumption of drugs is bad

        

 

 

 

 

 

 

 

Resolving Evaluative Disagreements

 

Inconsistencies

 

Consequence

 

Consensus

        

 

 

 

 

 

 

 

Resolving Evaluative Disagreements / Inconsistencies      

 

"How can you not like this, you claim to love all things X"

        

 

 

 

 

 

Resolving Evaluative Disagreements / Consequence

 

"we can show how our position would lead to good results and the opposite position would have undesirable consequences"

        

 

 

 

 

 

 

 

 

Resolving Evaluative Disagreements / Consensus     

 

"An even more positive method of reaching agreement about value judgments is to point to some moral consensus that exists beneath the level of the dispute"

 

"if we can all agree on some basic values that underlie those in dispute, we can build upward from that common ground"

        

 

 

 

 

 

 

 

 

 

Tying It Out        

 

I. 3

 

I. 5

 

I. 6

 

I. 8

 

I. 10

        

 

 

 

 

 

Part Two  

        

Reasoning Things Out       

Relevance in Arguments, Adequate Truth, and Alternative Possibilities

          

        

Relevance         

Relevance "refers to whether the reasons or evidence apply to our conclusion"

 

True justification ­ relevant justification

        

 

 

 

 

 

 

 

 

E.G.s of Irrelevance  

He is a good knitter because he has a good ear for music. 

 

Here, "the reasons we give are irrelevant to the claim they are supposed to support." 

        

 

 

 

 

 

 

 

 

 

Problems w/ Relevance    

Determining relevance can be quite difficult

        

 

 

 

 

 

 

 

        

Answers w/ Relevance     

"The fact of twilight does not make it impossible to differentiate night and day"

 

        

 

 

 

 

 

 

 

 

 

 

 

 

Adequacy

How much evidence is needed? 

 

As much as possible, within reason

 

 

 

 

 

 

 

        

Inadequate       

Inadequate evidence when, "the base is much too narrow to support the conclusion"

        

 

 

 

 

 

 

 

 

 

 

E.G.s of Inadequate Proof      

"Sometimes we hear people claim that there's no link between smoking and cancer because an uncle or grandfather smoked three packs a day and lived to age 94"

        

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Adequacy ­ Relevance      

"In the case of smoking, our uncle's longevity certainly applies to our claim, but it's just not enough to warrant it.  We would need a lot more evidence before anyone would be convinced"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

        

Generalizations & Exceptions    

Singular instances of contradictory occurrences are usually inadequate to disprove a generalization

 

The opposite is the case: exceptions can show a generalization to be accurate

        

 

 

 

 

 

 

 

 

 

 

 

So Far        

"the overall point [so far] is that in our arguments we need evidence that is adequate to prove our case as well as evidence that is true and relevant"

        

 

 

 

 

 

 

 

 

 

 

 

 

Alternatives      

Arguments for one procedure that may work can nevertheless not be desirable, especially when there are alternative ways of proceeding that also work

        

"No one would doubt that the guillotine is an infallible remedy for migraines headaches.  It would certainly be effective, but at too high a price"

 

"although an action may work, that does not mean it is the best way of solving a problem"

        

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alternatives E.G.       

 

Argument to cut costs in a large manufacturing firm

 

Action: 

 

Lay off "older, higher salaried employees whose productivity is decreasing"

 

Argument: 

 

Saves money

 

Increases competitive edge

 

Not a charity anywho

 

 

 

 

 

 

 

 

Alternatively,

 

Action: 

Incentivize early retirement, or offer half-time contracts

 

Argument: 

 

Money can be saved by other means

 

Loss of "most experienced" will affect others' loyalty, commitment, and morale

 

Loss of institutional knowledge

 

"Even if firing older employees would be effective, it may not be the best policy"

 

Again, "although an action may work, that does not mean it is the best way of solving a problem"