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-§ 1 "Composition Fallacy"

"In the composition fallacy one argues that since each part of the whole has a certain feature, it follows that the whole has that same feature." 

The Form of ...

The fallacy has this form: "Every part of X has the feature f. Therefore, the whole X has the feature f." 

This can be tricky. 

Having that form is not enough to commit the fallacy. 

One argument can have this form and work while another argument can have the exact same form and end up being fallacious. 

"The difference between the two arguments is not their form, but their content. That is, the difference is what feature is being attributed to the parts and wholes." 

Caution

"[Y]ou cannot generally identify any argument that moves from statements about parts to statements about wholes as committing the composition fallacy because whether or not there is a fallacy depends on what feature we are attributing to the parts and wholes." 

An argument can go "from claims about the parts possessing a feature to a claim about the whole possessing that same feature, [without committing] the composition fallacy."     

Understanding the Content

To spot the fallacy, we need to "understand the relationship between the concepts involved." 

"[I]n order to identify whether an argument has committed the composition fallacy, one must understand the concepts involved in the argument."   

"[W]e have to rely on our understanding of the meanings of the words or concepts involved," to tell the difference.

Examples

Is this a fallacy?    

1) Don't put salt on your food! Don't you know that sodium can be explosive (which can be deadly), and chlorine is poisonous (which can be deadly)!?!

Examples

Is this a fallacy?   

2)  Each part of the ceiling is less than eight feet long.  Therefore, the entire ceiling is less than eight feet long. 

Examples

Is this a fallacy?   

3)  Each part of the ceiling reflects light.  Therefore, the entire ceiling reflects light. 

Examples

Is this a fallacy?   

4) Any thought you think is about one thing, so all of your thoughts are about one thing.