Bottom-up justification:
| Definition | Example |
| An argument of the following form. “a” has the positive quality “x” and belongs to the group “A”. Therefore “A”s have “x”. | My neighbor is a banker, and a really nice guy. Therefore, bankers are nice guys. |
| Also known as: a dicto simpliciter ad dictum secundum quid / faulty generalization | |
| Notes | |
| A more detailed treatment of this fallacy can be found on the supplementary Inductive Errors page. | |
Case Study One
If a convenience store clerk successfully disarms a would-be robber, this is not evidence that confronting robbers is the best policy. A much larger sample of cases would be necessary before any inductive conclusion can be made.
Case Study Two
If your friend wins the lottery after entering a number based on his birthday and weight, this is not evidence that combining a participant’s birthday and weight will yield a number that is in any way connected to a winning lottery number.
Case Study Three
When confronted with statistical data that smoking is harmful, claiming that your smoking 105-year-old uncle disproves the statistics is a bottom-up justification fallacy.
Case Study Four
If, when shown statistical evidence that acquiring a university degree increases your chances of acquiring a satisfying carreer, you invoke successful college drop-out Bill Gates in an attempt to invalidate the statistics, you have committed the bottom-up justification fallacy.
Keep in mind that a fallacious argument does not entail an erroneous position.
Logfall - Logical Fallacies 