Lecture Notes by Christopher Lay

Los Angeles Pierce College

Department of History, Philosophy, and Sociology

 

 

 

 

Mathew Van Cleave's 2016 Introduction to Logic and Critical Thinking

 

https://open.umn.edu/opentextbooks/BookDetail.aspx?bookId=457

 

 

 

 

Chapter 4 "Informal fallacies", § 1 "Formal vs. Informal Fallacies," Sub-§ 4 "False Dichotomy"

"A false dichotomy is simply a disjunction [that is, an either/or statement] that does not exhaust all of the possible options."

 

 

 

 

 

 

 

 

 

 

Formalization

We can express it this way: "the form of a disjunctive syllogism [is] A v B ~A ∴ B"

 

A v B = Either A or B

~ A             = Not A

∴ B            = Therefore, B

 

 

 

 

 

 

 

 

 

The Problem

The problem with the fallacy of false dichotomy is that "the first premise presents two options as if they were the only two options, when in fact they aren’t, the first premise is false and the argument fails." 

 

 

 

 

 

 

 

 

The Form is Not the Problem

"Notice that the form of the argument is perfectly good—the argument is valid. The problem is that this argument isn’t sound because the first premise of the argument commits the false dichotomy fallacy."  

 

 

 

 

 

 

 

 

 

A Bush Example

"In a speech made on April 5, 2004, President Bush made the following remarks about the causes of the Iraq war: 'Saddam Hussein once again defied the demands of the world. And so I had a choice: Do I take the word of a madman, do I trust a person who had used weapons of mass destruction on his own people, plus people in the neighborhood, or do I take the steps necessary to defend the country? Given that choice, I will defend America every time.'"  

 

"The false dichotomy here is the claim that: Either I trust the word of a madman or I defend America (by going to war against Saddam Hussein’s regime)." 

 

"The problem is that these aren’t the only options. Other options include ongoing diplomacy and economic sanctions. Thus, even if it true that Bush shouldn’t have trusted the word of Hussein, it doesn’t follow that the only other option is going to war against Hussein’s regime. (Furthermore, it isn’t clear in what sense this was needed to defend America.) That is a false dichotomy." 

 

 

 

 

 

 

 

 

 

Understanding the Content

"As with all the previous informal fallacies we’ve considered, the false dichotomy fallacy requires an understanding of the concepts involved. Thus, we have to use our understanding of world in order to assess whether a false dichotomy fallacy is being committed or not."

 

 

 

 

 

 

 

 

 

 

 

Examples

Is this a fallacy?    

1) Justin Beaver is either genuinely talented or popular. 

2) Justin Beaver is not genuinely talented.

3) Therefore, Justin Beaver is popular. 

 

 

 

 

 

 

 

 

 

Examples

Is this a fallacy?   

1) This lecture is either informative, or a waste of time. 

2) This lecture is no waste of time.

3) Therefore, this lecture is informative. 

 

 

 

 

 

 

 

 

 

Examples

Is this a fallacy?   

1) You are either asleep or you are awake.   

2) You are not asleep. 

3) Therefore, you are awake. 

 

 

 

 

 

 

 

 

 

Examples

Is this a fallacy?   

1) You are either dead or alive.   

2) You are not dead.

3) Therefore, you are alive.   

 

 

 

 

 

 

 

 

 

Examples

Is this a fallacy?   

1) You are either tired of these fallacies, or excited to hear more. 

2) You are not excited to hear more. 

3) Therefore, you are tired of these fallacies.