answer:I think the difference is a matter of scale. In your example, you’re right, nearly every book is heavier than nearly every insect. So let’s (for the sake of argument, not accuracy) quantify the statement as true 99% of the time. But in matters of human behavior, everything is so much more variable. So the statements people make—e.g., “Girls are mean” (fictional example)—are almost never even close to 99% true. Maybe 10%, if you’re lucky. Also, your example is a statement of fact. If we stick with my fictional example, girls being mean isn’t necessarily a statement of fact so much as an opinion, or something that’s context-dependent. What’s mean to one person might be totally appropriate to another; heaviness, on the other hand, is not up for debate. Last, I think this negativity toward generalization is a reaction to people trying to generalize about all/most humans based on one’s own very limited personal experiences. Doing so is often not very accurate. If you can support your generalization with research studies or data rather than personal anecdotes, I’ll be much more likely to get on board with it.