Overgeneralization is a logical fallacy in which a selected subset of examples are taken to be representative of the whole, without examining all of the available evidence or using due diligence to collect a reasonably large sample.
Forms of overgeneralization include:
- hypernormalization: If something doesn't fit the overgeneralized definition of a category, then that thing doesn't belong in the category.
- "Everyone I know..." logic:
- These people do a thing, therefore everyone does it. (Or: These people don't do a thing, therefore nobody does it.)
- All the examples I know of fit into these two categories, therefore there are exactly two categories and no other options.
- argument by label: These examples belong in a particular category, which also has other attributes. Those attributes therefore also apply to this category.