description

Hasty Generalization occurs when a premise is a generalization about a class, derived from an inadequate sample. This comes in several forms, the most common of which is overgeneralization, but there is also a special type called 'fallacy of composition'. The assumption that if something is true of every individual unit within a class, that it is also a property of the class. For example, if one person in a crowd can see better by standing on her seat, it does not follow that if the whole audience stood on their seat that they would see better.

Note: a sweeping generalization is sort of the opposite of a hasty generalization. A sweeping generalization lets us characterize a single unit by its membership in a category. A hasty generalization works in the other direction: we hastily describe a category from too few examples.

Also, a hasty generalization has a special problem that we call confirmation seeking. This is the habit of starting with an hypothesis and going out and looking for just one piece of confirmatory data instead of trying to get a feel for what all the data would really look like. It's also related in this way to selection bias.

examples

"I had a barfy sandwich on the flight. Therefore, all airline food is substandard."

"I grew up next to a cheap Scottish family; I guess it's true that Scots are skinflints."

I hypothesized that all crows are white, and the first crow I came across was white, so it turns out I was right.