# logical/rhetorical fallacy

**URL:** <https://boards.straightdope.com/t/logical-rhetorical-fallacy/107714>\
**Category:** Factual Questions\
**Created:** [May 7, 2002, 1:44pm UTC](https://boards.straightdope.com/t/logical-rhetorical-fallacy/107714 "2002-05-07T13:44:48Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![drhess](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@drhess](https://boards.straightdope.com/u/drhess)\
**Post date:** [May 7, 2002, 1:44pm UTC](https://boards.straightdope.com/t/logical-rhetorical-fallacy/107714/1 "2002-05-07T13:44:48Z")

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Is there a name for the logical fallacy one often sees in debates that goes something like this: “You are for A, therefore you must believe B, C,D (or you must also be one of those people that often believe B,C,D who also believe A).”

Get my drift?

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**Author:** ![mack](https://avatars.discourse-cdn.com/v4/letter/m/b19c9b/32.png) [@mack](https://boards.straightdope.com/u/mack)\
**Post date:** [May 7, 2002, 1:58pm UTC](https://boards.straightdope.com/t/logical-rhetorical-fallacy/107714/2 "2002-05-07T13:58:49Z")

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I don’t know the answer to your question but more than likely it resides here:  
[http://www.geocities.com/phineasbg/kirklogic.html](http://www.geocities.com/phineasbg/kirklogic.html)

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**Author:** ![El\_Zagna](https://avatars.discourse-cdn.com/v4/letter/e/d2c977/32.png) [@El\_Zagna](https://boards.straightdope.com/u/El_Zagna)\
**Post date:** [May 7, 2002, 1:59pm UTC](https://boards.straightdope.com/t/logical-rhetorical-fallacy/107714/3 "2002-05-07T13:59:18Z")

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I’m afraid I can’t answer your question, but here are some good sites for exploring logical fallacies:

[Fallacies](http://www.nizkor.org/features/fallacies/)  
[Formal Logic and Logical Fallacies](http://www.mtroyal.ab.ca/programs/arts/english/dhyttenrauch/logic.htm)  
The Atheism Web Logic & Fallacies  
[The logical Fallacies Index](http://www.datanation.com/fallacies/index.htm)  
[The Logical Fallacies](http://www.dissension.com/logic/logic.html)

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**Author:** ![Patty\_O\_Furniture](https://avatars.discourse-cdn.com/v4/letter/p/96bed5/32.png) [@Patty\_O\_Furniture](https://boards.straightdope.com/u/Patty_O_Furniture)\
**Post date:** [May 7, 2002, 2:11pm UTC](https://boards.straightdope.com/t/logical-rhetorical-fallacy/107714/4 "2002-05-07T14:11:08Z")

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There are a number of fallacies that fit this description, but the most general would be a _non sequitur_, meaning “it does not follow”. The only place where B always follows A is in the Roman alphabet.

It could also be an _ad hoc_ fallacy, which is an attempt to give an after-the-fact explanation that may not be supported by evidence.

[More fallacies.](http://www.infidels.org/news/atheism/logic.html)

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**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\
**Post date:** [May 7, 2002, 2:54pm UTC](https://boards.straightdope.com/t/logical-rhetorical-fallacy/107714/5 "2002-05-07T14:54:12Z")

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The name of this fallacy is stereotyping. Basically, you’re stereotyping whenever you assume that what’s true for a proportion of the group is true for every member of the group.

I’m not 100% sure that your second example is fallacious. If those who believe A often also believe B, C, and D, then if you meet someone who believes A, there’s a good chance that they also believe B, C, and D. Just don’t assume that they must unless they tell you.