Informal Fallacies
Key Terms
Modus Ponens
Modus Tollens
Disjunctive Syllogism
Reduction Fallacy
Post Hoc Ergo Propter Hoc
- Not logical
- Pseudo-reasoning (false reasoning)
- Unsound arguments
Fallacies of Cause
- Deny, confuse, or falsify the cause related to an argument
- Four types:
- Reduction fallacy
- Post hoc ergo propter hoc
- Texas Sharpshooter fallacy
- Tautology
Post Hoc Ergo Propter Hoc
- Latin phrase that means “after this, therefore because of this.”
- Often shortened to Post hoc fallacy. It is also called false cause or correlation not causation
- The structure or form of a post hoc fallacy is:
Post Hoc Fallacy
This occurred. Then that occurred.
Therefore this caused that.
Example
- We won the game! I’m never washing these socks again!
- There is an increase in college enrollment and crime. Therefore, college enrollment causes crime.
Problems
- Conclusions drawn from insufficient information
- This fallacy assumes causation when in fact there may be no connection
- Particularly hazardous in research and debate