Whenever we dismiss a claim because of its origin or history
Examples:
You can't believe Bob's idea because it came from his dream
That's not possible because he got the idea from a science-fiction film
Pythagoras Theorem can't be true because he got it after smoking a joint
Conclusions:
- To avoid this fallacy focus on the argument itself not on its origin or history
- A bad source doesn't make an argument bad. Bad premises make an argument bad
People fall for this fallacy because they can confuse reason with causes